CN120946613A - Impellers for compressors, methods for machining compressor impellers, methods for manufacturing compressor impellers, and rolling equipment. - Google Patents
Impellers for compressors, methods for machining compressor impellers, methods for manufacturing compressor impellers, and rolling equipment.Info
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- CN120946613A CN120946613A CN202511475887.4A CN202511475887A CN120946613A CN 120946613 A CN120946613 A CN 120946613A CN 202511475887 A CN202511475887 A CN 202511475887A CN 120946613 A CN120946613 A CN 120946613A
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Abstract
一种用于压缩机的叶轮，包括背盘、轮毂和叶片，其中，轮毂与背盘构造成一体并且轮毂在外缘处成一体地连接到叶片的根部，在轮毂的外缘与叶片的根部之间存在过渡圆角，在各过渡圆角处设置经滚压的区域，在该区域中由于滚压产生凹痕。通过在压缩机的叶轮的过渡圆角处设置经滚压的区域，在该区域中经滚压产生的残余压缩应力能抑制或减缓在叶轮运行时在过渡圆角区域处由于疲劳发生“披萨切”失效。此外，还提出了一种加工压缩机的叶轮的方法、制造压缩机的叶轮的方法以及一种滚压设备。
An impeller for a compressor includes a back plate, a hub, and blades. The hub and back plate are integrally formed, and the hub is integrally connected to the root of the blades at its outer edge. A transition fillet exists between the outer edge of the hub and the root of the blades. A rolled area is provided at each transition fillet, in which indentations are created due to rolling. By providing rolled areas at the transition fillets of the compressor impeller, the residual compressive stress generated by rolling in these areas can suppress or mitigate "pizza-cut" failure due to fatigue at the transition fillet areas during impeller operation. Furthermore, a method for machining a compressor impeller, a method for manufacturing a compressor impeller, and a rolling device are also proposed.
Description
Technical Field
The present invention relates to the field of impellers for compressors. In particular, the present invention relates to an impeller of a compressor, a method of machining an impeller of a compressor, and a method for manufacturing an impeller of a compressor, and a rolling apparatus.
The invention relates to a method for machining an impeller of a rotary machine. The invention also relates to a fixture for fixing the rotary machine during machining. Furthermore, the invention relates to a blade for a rotary machine.
Background
The impeller of the compressor is used to compress air in the turbocharger. The impeller often rotates at hundreds of thousands of revolutions per minute during operation, and thus fatigue resistance is critical.
There are currently three major failure modes of the compressor wheel, namely "pizza cut" (pizza cut), hub burst and backfire failure. In these three fatigue failure modes, all failures are induced by tensile stress at the point of fatigue initiation.
For hub bursting, in this failure mode, fatigue cracks start from the hub central hole. At present, residual compressive stress is introduced through a reaming process of a hub central hole, so that crack initiation and expansion of a hub area of the impeller can be restrained, and failure is controlled to a certain degree.
For backface pan failure, fatigue cracks begin with the backface pan in this failure mode. Such failure can be controlled by optimizing the geometry of the back plate by means of finite element analysis, etc., and surface treating the back plate.
As for "pizza", in this failure mode, fatigue cracks begin at the hub transition fillet of the impeller. For this failure mode. There are still attempts in the art to find ways to effectively address or control the progression of such fatigue failure.
Disclosure of Invention
The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an impeller for a compressor, which can effectively suppress or slow down occurrence of a "pizza" failure mode at a transition fillet of a hub of the impeller. This object is achieved by an impeller comprising a back plate, a hub and blades, wherein the hub is constructed in one piece with the back plate and the hub is connected integrally at the outer edge to the root of the blades of the impeller, there being transition fillets between the outer edge of the hub and the root of the blades, the impeller being provided with a rolled region at each transition fillet, in which a dent is created by the rolling.
In the impeller for a compressor according to the present invention, by providing a rolled region at a transition fillet between an outer edge of a hub of the impeller and a root of a blade, the region being dented due to deformation by rolling, and by introducing residual compressive stresses due to rolling, these introduced residual compressive stresses are gradually released in subsequent use of the impeller, tensile stresses generated in operation can be offset, occurrence of "pizza-cut" failure due to fatigue at the transition fillet region of the hub of the impeller as the impeller rotates can be suppressed or slowed down, and resistance of the impeller to the "pizza-cut" failure mode is enhanced.
Preferably, the depth of the indentations in the transitional fillet area of the hub of the impeller due to rolling is 0.03 to 0.05 mm.
It has been found that the creation of permanent dimples having a depth within the above-mentioned range by rolling the transition fillet region of the hub of the impeller makes it possible on the one hand to effectively suppress the occurrence of "pizza" failure in the subsequent operation of the impeller, and on the other hand to avoid affecting the strength of the impeller itself, for example causing breakage, due to the too deep dimples produced by the rolling process, while also avoiding failing to introduce sufficient residual compressive stress due to the insufficient dimple depth produced by the rolling process and thus failing to desirably counteract the tensile stress produced by the operation of the impeller to suppress or slow down the occurrence of "pizza" failure.
Preferably, the rolled region of the impeller lies in the range between 0.8 to 1 times the outer diameter of the impeller.
It has been found that rolling the area of the impeller at the transition fillet within the above range to create the dimple effectively inhibits the occurrence of "pizza" failure, yet avoids adversely affecting the strength of the impeller itself by over-rolling the impeller range.
In an advantageous embodiment of the invention, the rolled region of the impeller is arranged such that its surface roughness is superior to the unrolled region of the root of the impeller's blades.
In this case, the region of the rolled transition bead of the impeller is provided with a surface roughness that is superior to that of the non-rolled region. The better surface roughness means fewer surface defects such as micro cracks, scratches, pits, etc. in the rolled region, which may become stress concentration points and easily become the starting points for fatigue crack initiation when the impeller is in operation. Thus, the superior surface roughness reduces stress concentration points that may exist in the areas of the transition fillets of the impeller where "pizza" failure would otherwise occur.
It is particularly preferred that the rolled region of the impeller exhibits a roughness better than Ra0.4.
It has been found that the surface roughness of the region of the rolled transition fillet of the impeller is better than Ra0.4 to suppress the occurrence of "pizza" failure during operation of the impeller, while also having a high rolling cost-effectiveness ratio for the impeller itself.
The invention also provides a method for processing the impeller of the compressor. The machining method includes the steps of fixing an impeller of a compressor by means of a jig, wherein a hub of the impeller is integrally connected to a root of a blade of the impeller at an outer edge, and a transition fillet exists between the outer edge of the hub and the root of the blade, positioning a rolling body to align a target area of the transition fillet of the impeller, and loading and rolling the target area at least once by means of the rolling body, thereby generating a dent in the rolled area.
The compressed impeller produced by the method of machining an impeller of a compressor according to the present invention can reduce or avoid the occurrence of "pizza" failure modes at the transition fillets of the machined impeller during operation. Specifically, in the method, by rolling a target area of a transition fillet of an impeller of a compressor at least once, deformation is generated in the rolled target area, a permanently deformed dent is formed, and a residual compressive stress is introduced in the target area. When the impeller of the compressor processed by the method runs subsequently, the introduced residual compressive stress counteracts the tensile stress when the impeller runs, so that the tendency of the occurrence of the pizza cutting failure at the transition fillet area of the hub of the impeller is restrained or slowed down, and the resistance of the impeller of the compressor processed by the method to the pizza cutting failure is improved.
The invention also proposes a method of manufacturing an impeller of a compressor. The manufacturing method includes the steps of fixing a blank of an impeller of a compressor by means of a jig, machining the blank to form a hub, a blade of the impeller such that the hub is integrally connected to a root of the blade at an outer edge, there is a transition fillet between the outer edge of the hub and the root of the blade, positioning rolling bodies to align a target area of the transition fillet of the impeller, and loading the target area by means of the rolling bodies to perform at least one rolling, thereby generating dimples in the rolled area.
With the method according to the invention for producing an impeller of a compressor, it is possible to produce an impeller from a blank of an impeller of a compressor, which has been notched in the region of the transition fillet of the hub of the impeller by rolling and has introduced residual compressive stresses, which impeller, in the subsequent operation, is able to suppress or slow down the occurrence of "pizza" failures at the transition fillet of the hub of the impeller by counteracting the residual compressive stresses with tensile stresses occurring in operation. In other words, in the manufacturing method, rolling is performed at least once on a target region of a transition fillet between an outer edge of a hub of an impeller manufactured from an impeller blank and a root of a blade, thereby introducing a residual compressive stress in the rolled region of the transition fillet. The residual compressive stress is gradually relieved as the impeller operates, thereby enabling a "pizza" failure to be inhibited or slowed down from occurring at the transition fillet of the hub of the impeller.
In a further embodiment of the method according to any of the preceding claims, it is provided that the target region of the transition fillet is rolled 5 to 10 times by means of the rolling elements.
It has been found that by rolling in the targeted area in the transition fillet of the impeller in the above-described range during processing or manufacturing of the impeller, it is ensured that sufficient residual compressive stress is introduced to slow or inhibit the occurrence of "pizza" failure without affecting the strength of the processed or manufactured impeller by excessive loads applied by a single rolling operation.
Alternatively, during these 5 to 10 rolls for the same target area, the load applied by each roll may be made the same, the first load applied during the first few preliminary rolls may also be made the same and the second load applied during the final roll after the first few preliminary rolls may be made the same, and the first load and the second load may be of different magnitudes, which is advantageous for forming dimples of a desired depth in the target area of the transition fillet.
Preferably, in an aspect of any of the above methods, the method further comprises the step of cooling the rolled region after loading the target region of the hub of the impeller for at least one rolling.
In the method according to the invention, by cooling the rolled region, if necessary after each rolling, overheating at the target region of the transition fillet of the impeller subjected to the rolling treatment is prevented, which would cause ablation or undesirable introduction of cracks in the rolled region and thus impair the quality of the processed or manufactured impeller.
Preferably, in the impeller of the turbine obtained according to the solution of any one of the above methods, the depth of the indentations produced in the rolled region is between 0.03 and 0.05 mm.
It has been found that in the method of machining or manufacturing an impeller of a turbine from a blank, the creation of dimples having a depth in the above-mentioned range in the target area of the transition fillet of the impeller by rolling makes it possible on the one hand to effectively suppress the occurrence of "pizza" failure modes of the machined or manufactured impeller of the turbine, and on the other hand to suppress the occurrence of "pizza" failure at the hub of the machined or manufactured impeller because the dimple depth formed is related to the number of rolling and the load applied at the time of rolling, the dimples in the above-mentioned range limiting the number of rolling and the magnitude of the load applied at the time of rolling the target area by the claimed machining or manufacturing method, thereby preventing both the strength of the impeller itself from being affected by the dimple depth created by rolling being too deep, for example causing breakage, and the failure to introduce sufficient residual compressive stress due to the dimple depth eventually formed being insufficient.
Preferably, in a variant of any of the above methods, the rolled region defining the rounded transition region of the hub of the impeller is in the range between 0.8 and 1 times the outer diameter of the impeller.
It has been found that in the processing or manufacturing method according to the invention, by performing the rolling energy in the fillet transition zone of the impeller within the above-mentioned range of the processed or manufactured impeller, the occurrence of "pizza cutting" failures is effectively suppressed in the transition fillet zone of the hub of the obtained impeller, which avoids that the range rolled in the rolling step is too large to adversely affect the strength of the impeller itself, and ensures the efficiency of the processing or manufacturing method according to the invention.
Preferably, the solution according to the invention for producing a compressor wheel from a blank further provides that the method further comprises, after rolling the target region of one transition fillet of the wheel produced from the blank, repositioning the rolling body relative to the blank in order to align the region to be rolled of the next transition fillet.
In this case, after rolling the target region of one transition fillet of the blank, the rolling bodies are repositioned relative to the blank in such a way that they can be aligned with the next transition fillet, for example a transition fillet adjacent to the previously processed transition fillet in the clockwise direction or in the counterclockwise direction. In particular, the rolling bodies are aligned with the region to be rolled of the next transition fillet, so that they can be positioned to roll against the target region of the next transition fillet, thereby also introducing residual compressive stresses in the target region of the next transition fillet. Finally, rolling of all transition fillets of the impeller of the compressor manufactured from the blank is accomplished by repeating the above steps, thereby introducing residual compressive stress at all transition fillets of the impeller, and thereby inhibiting or avoiding "pizza" failure at the transition fillets of the hub of the resulting compressor impeller. Such a method of manufacturing the resulting wheel with individually rolled transition fillets is particularly suitable for manufacturing compressor wheels in existing equipment for manufacturing compressor wheels, such as CNC machining centers, where the control unit of the equipment need only be modified to incorporate the rolling and repositioning steps described above, without the need to introduce additional machining tools or to provide specialized equipment to roll the wheel.
The invention also proposes a rolling device for an impeller of a compressor, comprising a fixing device for fixing the impeller of the compressor, a plurality of rolling bodies for rolling, and a control unit configured to process the impeller fixed at the fixing device according to the above-described method of processing the impeller of the compressor, so as to load and roll the impeller at target areas of respective transition fillets of the impeller by means of the plurality of rolling bodies, thereby generating dents at the rolled areas.
The invention thus proposes a rolling device for an impeller of a compressor, which is specially designed and constructed to roll the impeller of the compressor, capable of introducing residual compressive stresses due to loading or rolling of a plurality of rolling bodies at the target area of each transition fillet of the impeller, so as to counteract the tensile stresses generated by the impeller during rotary operation, thereby slowing down or inhibiting the occurrence of "pizza" failure at the transition fillet of the hub of the impeller of the compressor rolled by the rolling device.
In the rolling apparatus according to the present invention, it is possible to perform rolling processing to introduce residual compressive stress by controlling a plurality of rolling bodies of the rolling apparatus to process target areas of a plurality of transition fillets of an impeller by a control unit configured to perform the method according to the present invention, thereby enabling simultaneous rolling processing of target areas of a plurality of transition fillets of an impeller in one process, ensuring efficient rolling of an impeller of a compressor, that is, ensuring efficient introduction of residual compressive stress, the rolling apparatus is particularly suitable for mass processing of impellers of a plurality of compressors, improving operation efficiency.
In the context of the present invention, "primary machining" refers to rolling the transition fillet of the impeller of the compressor to obtain the desired dimple, and in "primary machining" the target area of the transition fillet of the impeller of the compressor may be rolled one time, or may be rolled multiple times to obtain the desired dimple to determine whether "primary machining" is completed, the desired dimple being a dimple having the desired properties of depth/surface roughness, etc.
Preferably, the depth of the indentations produced by rolling of the rolling bodies in the target region of the transition fillet of the impeller by means of the rolling device according to the invention is 0.03 to 0.05mm.
It has been found that with the rolling device according to the invention, the rolling of the rolling bodies produces indentations of a depth in the region indicated above in the target region of the transition fillet of the impeller, so that on the one hand, the occurrence of "pizza" failure of the rolled impeller at the transition fillet of the hub during operation is effectively suppressed, and on the other hand, the influence of the strength of the impeller itself due to the too deep depth of the indentations produced, for example, the breakage of the rolled impeller or a significant weakening of the strength at the rolled region, is avoided, while also avoiding the inability to introduce sufficient residual compressive stress in the region of the transition fillet of the impeller due to insufficient indentation depth, so that the occurrence of "pizza" failure cannot be suppressed or slowed down during subsequent rotational operation of the impeller.
Preferably, the rolled region rolled by means of the rolling bodies of the rolling device according to the invention lies in the range between 0.8 to 1 outer diameter of the impeller.
It has been found that the residual compressive stresses introduced by rolling the transition fillet in the above-mentioned range of the impeller prevent "pizza" failure during subsequent operation of the rolled impeller, and also avoid that the rolling range of the rolling bodies is too large to adversely affect the strength of the impeller itself, and that the rolling range also ensures the working efficiency of the rolling bodies.
Preferably, the rolling device according to the invention has rolling bodies with a radius dimensioned to be the same as the radius of the transition fillet of the rolled impeller.
Here, the rolling element of the rolling device is set to have the same radius as the radius of the transition fillet of the impeller, so that the rolling process is most efficient in the target region of the transition fillet of the impeller. Therefore, the rolling device can be provided with a plurality of groups of rolling bodies, wherein each rolling body in each group of rolling bodies has the same radius, and the rolling bodies in different groups have different radii, so that the rolling device can provide rolling bodies with different sizes according to the radius size of the transition fillet of the rolled compressor impeller when the rolling treatment is carried out, the rolling operation efficiency of the rolling device is improved, and the rolling device has a wider application range.
Preferably, the rolling apparatus according to the invention further comprises cooling means for cooling the rolled surface of the impeller.
The cooling device of the rolling device can cool the rolled surface of the impeller, and if necessary, the rolling device can further comprise a sensing device for monitoring the surface temperature of the impeller in real time, so that overheating at a target area of a transition fillet of the impeller subjected to rolling treatment is prevented, and the overheating can cause surface ablation or crack introduction at the rolling area, which can damage the quality, particularly the strength, of the rolled impeller.
Preferably, the hardness of the rolling bodies in the rolling device according to the invention is at least 20HRC higher than the hardness of the material of the impeller.
It has been found that in the case of rolling bodies of the rolling device having a hardness at least 20HRC higher than the hardness of the material of the rolled impeller, it is possible to effectively introduce residual compressive stresses into the rolled impeller and form dimples, whereby the introduced residual compressive stresses counteract the cable stresses during subsequent operation of the impeller, so as to suppress or slow down the occurrence of "pizza-cut" failures at the transition fillets of the hub of the impeller. Similarly, the rolling apparatus may have a plurality of sets of rolling elements, wherein each set of rolling elements has the same hardness, typically made of the same material, and the rolling elements of different sets have different hardness from each other, the hardness ranges of the rolling elements being selectable according to the hardness ranges of the materials of common turbine wheels to achieve a hardness at least 20HRC higher than the hardness of the materials of the wheels. The rolling device has the advantages that when the rolling device is used for rolling treatment, the rolling body group meeting the hardness requirement can be quickly selected according to the hardness of the rolled impeller, the rolling operation efficiency of the rolling device is improved, and the rolling device has a wider application range.
For example, in one non-limiting embodiment of the invention, the rolling elements of the rolling apparatus have a hardness of 35-40HRC for rolling the impeller made of aluminum alloy.
For example, in another non-limiting embodiment of the invention, the rolling elements of the rolling apparatus have a hardness of 55-60HRC for rolling an impeller made of titanium alloy.
It has been found that for common impellers made of aluminum alloys or of titanium alloys, the hardness of the rolling bodies of the rolling apparatus is configured to be effective in introducing residual compressive stresses into the rolled impeller within the above hardness ranges, thereby inhibiting or slowing down the occurrence of "pizza" failure modes in the impeller by the release of the introduced residual compressive stresses during subsequent operation of the impeller.
Preferably, the rolling apparatus according to the present invention further comprises supporting means for supporting the back plate of the rolled impeller.
The bearing device can support the back plate of the impeller of the compressor to be processed, so that deformation of the back plate of the impeller caused by the influence of the load applied by the rolling bodies when the rolling device rolls the transition fillet area of the impeller is avoided. In addition, the back plate can be fixed by the supporting device, so that the shaking of the back plate is prevented from possibly affecting the accuracy of the rolling body in rolling in the area of the transition fillet of the impeller, and the rolling treatment effect is adversely affected.
In a non-limiting embodiment of the present invention, the rolling apparatus further includes a plurality of loading arms, and the rolling bodies are respectively disposed at free ends of the loading arms, and the loading arms are configured to drive the rolling bodies to move relative to the impeller.
The design of the rolling device with multiple loading arms enables the rolling pressure to be output precisely by the loading arms, so that the rolling pressure of the rolling bodies can be ensured to be applied uniformly to the required pressure at the transition fillet areas of the rolled impeller, and the rolling bodies can be positioned precisely relative to the transition fillets to be rolled.
Additional features and advantages described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.
Drawings
Technical features of the present invention are clearly described in the following claims with reference to the above objects, and advantages thereof are apparent from the following detailed description with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention by way of example, without limiting the scope of the inventive concept.
FIG. 1 shows an impeller of a compressor in a perspective view;
Fig. 2 shows an impeller of a compressor in a perspective view;
FIG. 3 shows in elevation the impeller of the compressor shown in FIG. 2;
FIG. 4 illustrates in a rear view the impeller of the compressor shown in FIG. 2;
Figure 5 shows a flow chart of the processing of impellers in a dedicated rolling device according to the method of the invention;
FIG. 6 shows a flow chart of the method according to the invention for integrated machining of an impeller in a CNC, and
Fig. 7 shows a flow chart of an integrated machining impeller in a CNC according to another method of the present invention.
List of reference numerals
100 Impeller
101 Hub
102 Blade
110 Target area
OD outside diameter.
Detailed Description
Reference will now be made in detail to the various embodiments of the invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with the exemplary embodiments, it will be appreciated that the present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. For convenience in explanation and accurate definition in the appended claims, the terms "upper", "lower", "inner" and "outer" are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.
The inventors have discovered that in order to delay the occurrence of a "pizza" failure of the impeller of a compressor, the fatigue resistance of the impeller can be enhanced by introducing and/or increasing the residual compressive stress in the fillet area between the hub of the impeller of the compressor and the root of the blade, the occurrence of a "pizza" failure is delayed.
Specifically, by performing a rolling process at the transition fillet of the hub of the impeller and the root of the blade, residual compressive stress can be introduced in the impeller of the compressor. The occurrence of a "pizza" failure mode can be suppressed by means of this residual compressive stress. Such attempts to generate residual compressive stress by the rolling process to avoid fatigue failure have proven effective in the field of fasteners, for example, and such treatments have been found to significantly extend the useful life of the rolled fasteners.
The rolling of the turbine wheel may be performed in a special apparatus specially designed for rolling the transition fillet of the turbine wheel, or may be performed in a CNC numerical control machining center. This will be further explained below.
The impeller 100 is schematically shown in perspective view in fig. 1. The impeller 100 has a hub 101 and a plurality of blades 102. The area between the outer edge of the hub 101 to the root of the blade 102 is referred to as the transition fillet or transition fillet area.
The area to be rolled in the wheel transition fillet of the impeller 100, also called the area to be rolled or target area, is schematically shown in fig. 1 in a number of ovals, which has the reference numeral 110.
Fig. 2 schematically shows the impeller 100 in another angular perspective view.
Fig. 3 and 4 show the impeller 100 in front and rear views, respectively. As can be seen in fig. 3, the area to be rolled of the transition fillet of the hub of the impeller 100 lies in the range between 0.8 to 1 outer diameter OD of the impeller.
The surface roughness of the rolled region of the transition fillet of the impeller may be better than the surface roughness of the non-rolled transition fillet. For example, the surface roughness of the rolled region of the transition fillet of the impeller is better than Ra0.4.
The depth of the indentations in the rolled region of the transition fillet of the impeller due to rolling is 0.03 to 0.05 mm.
Embodiments of rolling the target region of the transition fillet of the impeller 100 within the above-described range in a dedicated rolling apparatus and in a CNC numerical control machining center are explained below with reference to fig. 5, 6, and 7, respectively.
Embodiment 1 Rolling impeller in dedicated rolling apparatus
As shown in the flow chart of fig. 5, the method of rolling a molded impeller of a compressor in a dedicated rolling apparatus, which is specifically designed and constructed for rolling the transition rounded corners of the impeller of the compressor, comprises at least the following steps:
1.1 Fixing an impeller of a compressor in a fixing device of a rolling device;
1.2 Adjusting the loading arm so that the loading arm is aligned with a region to be rolled of a transition fillet of the fixed impeller between the outer edge of the hub and the root of the blade;
1.3 Rolling the region of the transition fillet to be rolled by means of rolling bodies arranged at the ends of the loading arms, whereby dimples are produced by rolling in the rolled region;
1.4 And removing the impeller with the formed pits in the area of the transition fillet.
If a plurality of impellers need to be rolled, the next impeller to be rolled can be fixed in a fixing device of the rolling equipment, and the steps 1.1-1.4 are repeated to finish rolling the transition fillets of the next impeller. By rolling the transition fillet between the hub of the impeller of the compressor and the root of the blade, the introduction of residual compressive stress in the rolled region is realized, so that the fatigue resistance of the transition fillet region between the outer edge of the hub and the root of the blade can be improved by means of the introduced participating compressive stress, the occurrence of pizza cutting failure is restrained, and the service life of the impeller is prolonged.
It should be noted that rolling in step 1.3 above means that the rolling bodies with applied pressure at the ends of the loading arms are rolled at least once in the area to be rolled of the transition fillet of the impeller, whereas in order to create the required pit in the area of the transition fillet and the pit is fully formed, it is generally necessary that one rolling body is rolled repeatedly 5 to 10 times at one transition fillet of the impeller.
The special rolling device also has a support device for the back plate of the rolled impeller, thereby providing a support force for the back plate. This can prevent that the back of the body dish from taking place to remove at the in-process that the rolling element rolled over the fillet of transition of impeller to produce deformation, influence the future use of this impeller.
In this way, in the rolling device, the impeller can be fixed by means of the above-mentioned supporting device and fixing device, for example, a mandrel for the inner hole of the hub of the impeller, so as to provide support for rolling the impeller and avoid deformation, in particular irreversible deformation, of other parts of the impeller due to the rolling process.
The rolling device generally has more than one component for applying pressure and rolling, which is composed of a loading arm and rolling bodies arranged at the end of the loading arm. The rolling elements are brought into contact with the surface of the impeller to be processed during rolling, and are rolled, thereby leaving dents and introducing compressive stress. The rolling device is provided with a plurality of parts, so that each transition fillet of one impeller can be rolled in one processing step by means of one rolling device, and the rolling efficiency is improved.
The method and the special rolling equipment with the corresponding design structure are suitable for the scene of processing impellers in large batches, can realize flow production, realize synchronous rolling treatment of all transition fillets of a single impeller, and shorten the single-piece processing period.
The rolling elements of the rolling device are designed to contact the transition radius of the impeller and to apply pressure to the impeller via the loading arm. The rolling bodies are, for example, rollers, wheels or the like arranged at the free end of the loading arm. The rolling bodies should have the same radius as the transition fillet of the hub of the impeller to be rolled.
In general, the rolling device may include a plurality of sets of rolling elements having different radius sizes, so as to select an appropriate rolling element to roll the transition fillet according to the radius sizes of the transition fillets to be rolled of different impellers having different sizes, so as to ensure the high efficiency of the rolling process.
In general, the rolling device may also comprise rolling bodies made of different materials with different hardness ranges, since in order to ensure that rolling the transition fillet of the impeller deforms at the surface of the transition fillet of the impeller and introduces a residual compressive stress, the hardness of the rolling bodies should be at least 20 HRC (rockwell hardness) higher than the hardness of the material from which the impeller is made. For impellers made of aluminum alloys, the hardness of the rollers is desirably 35 to 40 HRC. For impellers made of titanium alloy, the hardness of the rollers is desirably 55 to 60 HRC. Having rolling bodies made of materials of different hardness makes it possible to select an appropriate rolling body according to the hardness of the impeller to be rolled, ensuring the quality and efficiency of the rolling process.
The rolling device is also provided with a driving source for driving the loading arm to move so as to complete the positioning of the area to be rolled of the transition fillet of the impeller and align the rolling bodies with the area to be rolled, and driving the rolling bodies to apply enough load to the transition fillet of the hub of the impeller and roll.
The rolling device further comprises a cooling unit for cooling the impeller during rolling, in particular the region of the rolled transition fillet, avoiding the occurrence of high-temperature induced ablation or crack initiation in the rolled region, which in turn causes damage to the impeller.
The rolled surface roughness of the transition fillet of the impeller may be better than the surface roughness of the non-rolled transition fillet.
The rolled surface roughness of the transition fillet of the impeller may be better than ra0.4.
The depth of the indentations created in the rolled surface of the transition fillet of the impeller is 0.03 to 0.05 mm. The depth of the indentation may be achieved by adjusting the load applied via the rolling bodies.
The rolled region of the transition fillet of the impeller is between 0.8 to 1 times the outer diameter of the impeller.
The speed at which each rolling element rolls along the surface of the impeller in each single rolling operation is determined by factors such as the output power of the driving source of the rolling device and the cooling power of the cooling unit of the rolling device.
Embodiment 2 Integrated machining in CNC
As shown in the flow chart of fig. 6, in addition to the embodiment 1 explained above, the rolling of the region of the transition fillet of the impeller to generate the dent introduction into the compressive stress may also be performed during the production of the impeller from the blank, that is, the rolling of the transition fillet in the processed impeller blank may be performed directly in CNC when the impeller is produced by CNC processing the blank.
The processing method at least comprises the following steps:
2.1 Fixing a bar stock or a forging blank for manufacturing the impeller in the CNC;
2.2 Machining the bar stock or the forged blank to form a hub of the impeller and a transition fillet at the root of the hub to the blade of the impeller;
2.3 Positioning a region to be rolled of a transition fillet;
2.4 Aligning rolling bodies of CNC to the positioned area to be rolled;
2.5 Rolling the region to be rolled, thereby forming dimples in the rolled region;
2.6 Moving the rolling body relative to an impeller manufactured by a bar stock or a forged blank so as to position a region to be rolled of a next transition fillet;
2.7 Repeating the steps 2.4 to 2.6 until the rolling of all the round corners of the impeller is completed.
The integrated processing method can realize online rolling in a CNC numerical control processing center, and the rolling process is included in the process of processing the impeller blank, so that the impeller processing process is optimized. From the point of view of the overall process flow of the impeller, this enables efficient shaping of the region of the transition fillet of the hub of the impeller with compressive residual stress.
By introducing compression participation stress, the fatigue resistance of the transition fillet area of the hub of the impeller is improved, the service life of the impeller is prolonged, and the occurrence of pizza cutting failure is restrained. This method of processing is particularly advantageous for small volume, high precision impeller production.
The rolling bodies in steps 2.4 to 2.6 may also be replaced by rolling heads in CNC.
The rolling elements or rolling heads are in contact with the surface of the area of the transition fillet of the impeller being processed when loaded, rolling action is performed, and dents are left on the rolled area of the impeller, so that residual compressive stress is introduced. To ensure the effect of introducing residual compressive stresses, the rolling bodies should have the same radius as the transition fillets of the hub of the impeller to be rolled. Therefore, in the step 2.1, when the blank is fixedly installed, the operator or the control unit of the CNC can synchronously determine the size of the impeller to be processed, including the outer diameter of the impeller and the radius of the transition fillet of the impeller, and select the corresponding rolling body or rolling head according to the radius of the transition fillet to execute the steps 2.5 and 2.6 so as to adapt to the size of the blank of the impeller, thereby ensuring the efficient rolling operation.
As shown in fig. 7, the method may further comprise the steps of 2.51 monitoring the rolled surface and 2.52 cooling the rolled surface after performing step 2.5 described above.
Step 2.51 is to monitor the surface of the rolled region of the transition fillet of the impeller using, for example, existing sensor units in CNC, to determine if an excessive temperature has occurred therein and if there is a visual change in the surface to prevent the rolling process from causing the temperature of the rolled region to rise, thereby causing ablation or crack introduction in the rolled region by the high temperature and alerting if necessary.
Step 2.52 is to cool the rolled region, for example using a cooling unit in CNC. By means of the cooling unit, the rolled surface can be cooled once after each rolling, the rolled surface can be cooled during rolling, or the rolled surface can be cooled after a plurality of rolling.
The CNC center should have a plurality of rolling bodies or rolling heads of different hardness. The hardness of the material of the rolling bodies or of the rolling heads is chosen to be at least 20 HRC (rockwell hardness) higher than the hardness of the material of the blank to be machined, so that rolling and indentation in the region of the transition radius of the blank can be successfully carried out in step 2.5. For aluminum alloy blanks, the hardness of the material of the rolling bodies or rolling heads is desirably from 35 to 40 HRC. For titanium alloy blanks, the hardness of the material of the rolling bodies or rolling heads is desirably 55 to 60 HRC.
The surface roughness of the rolled surface of the transition fillet of the blank may be better than the surface of the non-rolled transition fillet. For example, the surface roughness of the rolled surface is better than Ra0.4.
The depth of the indentations formed in the rolled region of the transition fillet of the blank is from 0.03 to 0.05 mm. The dimple depth can be controlled by the control unit of the CNC by adjusting the amount of load applied via the rolling elements or rolling heads. At the same time, it should be ensured that the magnitude of the applied load does not cause CNC alarms due to overload. If necessary, the desired dent can be formed by increasing the number of rolling. The rolled region is in the range of between 0.8 to 1 times the outer diameter of the impeller that the blank of the processed impeller ultimately forms, and is positionable by the mandrel of the blank for securing the impeller.
The speed at which the rolling bodies or the rolling heads roll in the region of the transition radius of the blank is jointly determined by factors such as the output power of the CNC drive source, the cooling power of the cooling unit and the like, and is regulated by the control unit.
It should be noted that the rolling in step 2.5 above means that the rolling elements or rolling heads are rolled at least once in the area to be rolled of one transition fillet of the hub of the impeller positioned in 2.3 and is not limited to only one rolling. Typically, the rolling elements or rolling heads require 5 to 10 rolls in the area to be rolled of a single transition fillet of the impeller to obtain the desired indentation. The load applied by each rolling may be the same or uniform or different. For example, the first rolling or first few times is a light press adjustment of the rolling bodies or rolling heads, while only the last or last few times is a relatively heavy press for complete forming of the dimples.
Embodiment 2 can be performed in existing CNCs by rolling heads without the need to manufacture or purchase special rolling equipment, which is less costly to manufacture as a whole. It is particularly advantageous for small batches of high precision impellers, such as those used in the aerospace field. In the CNC integrated machining method, the flexibility of the process is high, and the adjustment of the position of the rolling bodies, the load applied by the rolling bodies and the like can be realized by adjusting a machining program executed by the CNC through a control unit.
In the above, the two embodiments of rolling in a dedicated rolling apparatus and integrated processing including rolling in CNC have been described separately, and particularly, the number of times in which the rolling bodies roll the regions of the respective transition fillets has been described, but the present invention is not limited thereto.
For example, depending on the material of the impeller being machined, the future application scenario of the impeller, the depth of the indentations generated in the area of the transition fillet need not be 0.03 to 0.05mm, and may be greater or less than this range. For example, the roughness of the rolled region of the transition fillet may also be below Ra0.4 or above Ra0.4.
Accordingly, the number of rolls or rolling heads rolling against the same region of transition fillet may be more than 10 times or less than 6 times, whether in dedicated rolling equipment or in CNC.
In the above, the hardness of the rolling body or the rolling head is described in the case where the material of the impeller or the blank of the impeller is an aluminum alloy or a titanium alloy. However, the invention is not limited thereto, and the rolling bodies or rolling heads may be selected accordingly in accordance with the hardness of the other materials used to make the impeller or impeller blank to ensure that the hardness thereof is at least 20HRC higher than the hardness of the materials used to make the impeller or impeller blank.
The present invention can be freely combined with each other, or can be appropriately modified and omitted within the scope of the present invention.
Claims (21)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202511475887.4A CN120946613A (en) | 2025-10-16 | 2025-10-16 | Impellers for compressors, methods for machining compressor impellers, methods for manufacturing compressor impellers, and rolling equipment. |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202511475887.4A CN120946613A (en) | 2025-10-16 | 2025-10-16 | Impellers for compressors, methods for machining compressor impellers, methods for manufacturing compressor impellers, and rolling equipment. |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB777927A (en) * | 1953-07-14 | 1957-07-03 | Stewarts & Lloyds Ltd | A process and apparatus for the profiling of solid and tubular sections |
| CN201925227U (en) * | 2011-01-21 | 2011-08-10 | 宁波方太厨具有限公司 | Impeller with central disc structure |
| CN204603697U (en) * | 2015-06-03 | 2015-09-02 | 宋猛 | A kind of bent axle strengthening rolling device |
| CN213870434U (en) * | 2020-11-19 | 2021-08-03 | 四川云众宏图科技有限公司 | High-strength fan impeller |
| CN218062785U (en) * | 2022-03-02 | 2022-12-16 | 广州雷辰机电技术有限公司 | Impeller, fan and dust catcher |
-
2025
- 2025-10-16 CN CN202511475887.4A patent/CN120946613A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB777927A (en) * | 1953-07-14 | 1957-07-03 | Stewarts & Lloyds Ltd | A process and apparatus for the profiling of solid and tubular sections |
| CN201925227U (en) * | 2011-01-21 | 2011-08-10 | 宁波方太厨具有限公司 | Impeller with central disc structure |
| CN204603697U (en) * | 2015-06-03 | 2015-09-02 | 宋猛 | A kind of bent axle strengthening rolling device |
| CN213870434U (en) * | 2020-11-19 | 2021-08-03 | 四川云众宏图科技有限公司 | High-strength fan impeller |
| CN218062785U (en) * | 2022-03-02 | 2022-12-16 | 广州雷辰机电技术有限公司 | Impeller, fan and dust catcher |
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