RU2685624C2 - Method of sheet forging and differentiated pressure device of sheet forging press - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to metal forming, and can be used in die forging sheets to control local forces by preset algorithm. Differentiated clamping device is installed in dies to ensure control of metal flow and movement from periphery to deformation zone by means of local forces control during shaping of billet. Differentiated clamping device is made of sectors fixed on the plate, and each clamping sector is equipped with a hydraulic force transfer device according to the specified algorithm.

EFFECT: as a result, higher technological capabilities of sheet forming process and accuracy of manufactured parts.

4 cl, 19 dwg

Description

The invention relates to mechanical engineering, in particular to the processing of metals by pressure, and can be used in stamping dies for controlling local efforts according to a given algorithm.

There is a method of stamping a box from a sheet blank on a simple-action press (RF patent for invention No. 2527820, publ. 10.09.2014, bul. No. 25), which includes placing the blank in a die for drawing, pressing the flange of the blank with a pressing surface to the pressing surface of the die and drawing the box by drawing the flange of the workpiece into the gap between the punch and the die to form the wall of the box using the punch and die, the contours of which in the plan correspond to the contour of the box wall in the plan taking into account the thickness of this wall after drawing at the bottom of the box one or more holes, characterized in that pre-made sheet blank with punched holes located in places corresponding to dangerous sections in the process of drawing and located opposite the corner curves of the minimum radius of curvature of the box wall in the plan.

The disadvantage of this method is the low quality of the parts, as in the box-like parts are technological holes.

In addition, there is a method of multi-operation drawing of a box-shaped part from a sheet blank on presses of simple action or a multi-station automatic press (patent for the invention of the Russian Federation No. 2545863, publ. 12.27.2014, bullion No. 36). Stamps for the implementation of each operation of this method of drawing contain the following main working parts: punch, die and clamp. The punch is fixed on the fixed lower plate of the stamp, and the matrix on the movable upper plate. Inside the die there is an ejector of a stamped semi-finished product, acting from the pusher using a punch or press device. The clamp through the pushers rests on the press pad or the stamp buffer, which provides the necessary force to press the flange of the sheet blank and push the inclined wall of the previous semi-finished product into the die matrix to extract the next semi-finished product.

The disadvantage of the described method is limited technological capabilities associated with the need to use at each technological transition of new technological equipment, which also needs to be replaced when changing manufactured parts.

The prior art known device load control pillows and pressing machine, containing the device load control pillows (RF patent for the invention №2401742, publ. 10.04.2010, bull. No. 10), containing a pillow located under the slider press. The control device contains a hydraulic cylinder that forms a die cushion, a hydraulic control valve connected to it, a hydraulic source, an opening degree control unit, a die cushion lowering speed determination unit, a signal correction unit.

The disadvantages of the described device are limited technological capabilities due to the fact that the local clamping forces at different points are constant, but may vary in time. In addition, the implementation of the process of managing local efforts requires the use of special equipment.

To implement the sheet punching methods described, standard elements are used, namely mechanical and gas springs placed in the stamp between the clamp and the stamp block part (lower or upper plate) and / or damping devices built into the press.

Known design of the damping device using a pneumatic spring (RF patent for useful model No. 81541, publ. 20.03.2009, bull. No. 8), containing a reservoir, a piston rod with a piston, a guide with a lid, sequentially mounted on the rod, support ring, the second sealing element, forming a cavity with a lubricant fluid with the rod. The radial channels communicating with the cavity are made in the rod guide and the support ring, the first of which serves as a supply oil line, the second serves to discharge air from the cavity and has a non-return valve, in addition, the pneumatic spring contains a node for filling the cavity with a lubricant.

The disadvantage of this design is the constancy of the control algorithm for the transfer of local forces when the press acts on the clamp, due to the fact that local forces are transmitted according to a linear law depending on the displacement of the cylinder rod.

The objective of the proposed technical solution is to increase the technological capabilities of the sheet punching process and the accuracy of the parts produced, as well as the possibility of its use on universal equipment.

The technical result is achieved by the fact that the Differentiated clamping device of the stamp stamping is made in the form of clamping sectors fixed on a common plate, each of the clamping sectors is equipped with a hydraulic device for transmitting local efforts according to a predetermined algorithm. A hydraulic device for transmitting local forces according to a predetermined algorithm may comprise a housing, a piston rod, while rings with an internal surface of variable cross section are installed in the housing, which with the peripheral surface of the piston forms a gap that changes as the piston moves relative to the housing. A hydraulic device for transmitting local forces according to a predetermined algorithm may comprise a housing, a piston rod, while the rod is hollow with radial holes, and a movable ring is mounted on the piston, which has the ability to block the holes in the piston, and an axial section of variable cross section is installed in the housing, one end which is made in the form of a piston placed in the cavity of the rod, while the movable ring with a variable cross-section axis forms a gap that changes when the hollow rod with the piston and the ring moves relative to si

The essence of the proposed technical solution is demonstrated by the drawings. FIG. 1 shows a sheet stamping stamp with a differentiated clamping device; in fig. 2 - stamped sheet stamping with a differentiated clamping device, section AA; in fig. 3 - hydraulic device for transmitting force according to a predetermined algorithm according to the first embodiment; in fig. 4 - hydraulic device for transmitting force according to a given algorithm according to the second variant; in fig. 5 - stamped sheet stamping with a differentiated clamping device at the beginning of the forming process; in fig. 6 - hydraulic device for the transmission of force according to a given algorithm in the first embodiment at the beginning of the shaping process; in fig. 7 - hydraulic device for transmitting force according to a given algorithm according to the second variant at the beginning of the shaping process; in fig. 8 - sheet stamping stamp with a differentiated clamping device in the process of shaping; in fig. 9 - hydraulic device for transmitting force according to a given algorithm according to the first variant in the process of shaping; in fig. 10 - hydraulic device for transmitting force according to a given algorithm according to the second variant in the process of shaping; in fig. 11 - sheet punching stamp with a differentiated clamping device at the end of the shaping process; in fig. 12 - hydraulic device for transmitting force according to a predetermined algorithm according to the first embodiment at the end of the shaping process; in fig. 13 is a hydraulic device for transmitting force according to a predetermined algorithm according to the second variant at the end of the shaping process; in fig. 14 - change in the force at δ = 0.03 mm; in fig. 15 - change in the force at δ = 0.04 mm; in fig. 16 - change in the magnitude of the force at δ = 0.05 mm; in fig. 17 - change in the magnitude of the force at δ = 0.25 mm; in fig. 18 is a graphical dependence of the change in local forces on the size of the gap of the hydraulic force transmission device according to a predetermined algorithm, performed in accordance with the first embodiment; in fig. 19 is a graphical dependence of the change in local forces on the size of the gap of the hydraulic force transmission device according to a predetermined algorithm, performed according to the second embodiment.

The proposed method of sheet metal stamping is implemented using the following components: the upper 1 and lower 2 plates, on which the punch 3 and the matrix 4 are rigidly mounted, respectively. In addition, a differential clamping device 5 is installed on the upper plate 1, consisting of several hydraulic force transfer devices 6 According to a predetermined algorithm and clamp 7. The hydraulic device 6 for transmitting power according to a predetermined algorithm comprises a housing 8, a rod 9, one end of which is fixed on the upper plate 1, and the other end is designed as a piston 10. In the housing 8 there are rings 11, which have an inner surface of variable section 12. Between the peripheral surface of the piston 10 and the inner surface of variable section 12 of the rings 11 there is a gap δ. A cover 13 is installed on the end surface of the housing. Inside the housing 8 a spring ring 14 is placed, limiting the stroke of the air piston 15 with sealing rings 16 installed between the housing 8 and the rod 9. A spring 17 is installed between the air piston 15 and the cover 13 transferring the load according to a given algorithm, which contains a hollow rod 18 with radial holes 19, which can move along an axis of variable section 20, one end of which is made in the form of a piston 21 with seals 22, and the second through a threaded connection 23 is fixed in the housing 8. The rod 18 has a piston 24 with holes 25 around its perimeter and sealing rings 26. A ring 27 is mounted on one of the ends of the piston 24 Ring 27 together with the holes 25 and the spring ring 28 mounted in the piston 24, forms a check valve. In addition, the ring 27 together with the axis 20 forms a gap Δ. The clamp 7 consists of separate sectors 29 rigidly mounted on a common steel plate 30 to which the housings 8 of the hydraulic devices 6 for transmitting power are attached according to a predetermined algorithm. When this case 8 are located opposite the respective sectors 29.

Consider the use of sheet punching method and the operation of a differentiated clamping device on the example of shaping a box section. Standard sheet metal punching technology involves the use of gas or mechanical springs, with local efforts being transferred to a rigid clamp. The magnitude of the clamping force is chosen from the calculation, ensuring the flow of metal in the places of dislocation of maximum internal stresses at the initial moment of shaping and extends to the entire surface of the contact of the clamp with the part. As the spring is compressed by the slider, the force increases and does not depend on the value required for the optimal shaping process. In this case, such defects as excessive thinning up to rupture, or thickening up to wrinkling may occur.

In the proposed method in the process of shaping the management of local efforts is as follows. At the initial stage, a calculation is made, allowing to determine the optimal local clamping forces in different zones of the workpiece and at different points of the shaping process. Based on the data obtained, the required number and the relative position of the clamping sectors 29, which are mounted on the elastic plate 30, thereby forming the clamp 7. For each sector 29, the force transmission devices 6 are attached according to a predetermined algorithm. The clamp 7 and the device 6 form a differential clamping device 5, which allows you to control local efforts in the stamp. The punching process is carried out by moving the top plate 1 together with the punch 3 and the differentiated pressure device 5 relative to the bottom plate 2 on which the die 4 is fixed. At the initial time, the differential pressure device 5 clamps the workpiece with the calculated forces provided by the force transfer devices 6 according to a predetermined algorithm. The magnitude of the force on each of the sectors 29 is different and corresponds to the optimal value for the shaping process at a given time and in the given pressure zone 7. The change in the force for each force transfer device 6 according to a given algorithm is determined by the size of the gaps δ or Δ. The next time the punch comes to the surface of the workpiece and begins to deform it. At the same time, in order to ensure the optimality of the shaping process, changes in local efforts are required in the clamping sectors 29. Further deformation of the workpiece also leads to a redistribution of local efforts in the clamping sectors 29, which continues until the completion of the shaping process and is ensured by the control carried out by the device 6.

Two versions of the hydraulic device for the transmission of force according to a given algorithm are proposed, and, accordingly, two options for the operation of a differentiated clamping device. Consider both options.

The operation of the hydraulic device 6 of the transmission of forces according to a given algorithm according to the first embodiment is as follows. At the initial time, the rod 9 and the piston 10 are in the upper position, while the pressure in the cavity under the piston is equal to the atmospheric pressure. When moving the rod 9 down under the action of the top plate 1 of the stamp attached to the press slide in the cavity under the piston of the rod pressure increases. The pressure in this case is determined by the speed of movement of the rod 9 and the size of the gap δ between the inner surface of a variable section 12 of the rings 11 and the peripheral surface of the piston 10. The speed of movement of the rod 9 depends on the speed of movement of the press ram and can change to zero. The rings 11 mounted inside the housing 8 are made with internal surfaces of variable cross-section 12. As the peripheral surface of the piston 10 passes through the rings 11, the size of the gap 8 between them changes. Changing the gap δ allows you to adjust the flow rate of the working fluid from the cavity under the piston 10 into the cavity above the piston and, accordingly, controls the pressure in the cavity under the piston 10, which is transmitted through the housing 8 to the pressure sectors 29. The shape of the inner surfaces of the rings 11 is determined by calculation from conditions for ensuring an optimal shaping process for this pressing sector and, together with the peripheral surface of the piston 10, sets the algorithm for controlling the transmission of force from the press slide through the upper plate the sector-specific clamping rings 29. The number 11 is dependent on the complexity of the control algorithm. The working fluid in the cavity above the piston moves the air piston 15, compressing the spring 17. The shape of the inner surfaces of the rings 11 is determined by calculation from the condition of ensuring an optimal shaping process for this pressing sector and, together with the peripheral surface of the piston 10, sets the algorithm for controlling the transfer of pressure from the press slider through the top plate to a specific sector of the pressure 29. When reverse movement of the rod 9, the working fluid above the cavity of the piston 10 under the action of the weight of the housing 8 and the pressure 7, as well as the accumulated energy uu spring 17 flows from the cavity above the piston into the cavity below the piston. The ring 14 is designed to limit the movement of the air piston 15. Sealing rings 16 prevent the penetration of the working fluid into the air chamber formed by the air piston 15, the lid 13 and the inner walls of the housing 8.

The operation of the hydraulic device 6 transmission of power according to a given algorithm according to the second variant is as follows. At the initial time, the hollow rod 18 and the piston 24 are in the upper position, while the pressure in the cavity under the piston is equal to the atmospheric pressure. When moving the rod 18 down under the action of the top plate 1 of the stamp attached to the press slider in the cavity under the piston of the rod, the pressure increases and presses the ring 27 to the end surface of the hollow piston 18, which closes the holes 25. The opening of the ring 27 and the outer surface of the axis 20 form a variable the gap Δ, through which the working fluid flows into the cavity formed by the axis 20 and the inner surface of the hollow stem 18. Next, through the radial holes 19, the working fluid enters the cavity above the piston 24. The pressure under the pore 24, it is then determined moving speed of the rod 18 and the size of the gap Δ between the orifice ring 27 and the outer surface of the axle 20. The speed of movement of the rod 18 depends on the speed of movement of the slide and the press can be changed to zero. The axis 20, having a variable cross-section, is fastened to the bottom of the housing 8 by means of the thread 23. As the piston 24 with the ring 27 moves relative to the axis 20, the gap size Δ changes. Changing the gap Δ allows you to adjust the flow rate of the working fluid from the cavity under the piston 24 into the cavity above the piston and, accordingly, controls the pressure in the cavity under the piston 24, which through the housing 8 is transferred to the pressing section 29. The shape of the surface of the axis 20 is determined by calculation from ensuring an optimal shaping process for this sector of the pressing 29 and, together with the opening of the ring 27, sets the algorithm for controlling the transfer of force from the press ram through the upper plate 1 to the specific production sector Izyma 29. Sealing rings 26, placed on the piston 24, prevent the penetration of the working fluid into the cavity above the piston, bypassing the gap Δ. The working fluid in the cavity above the piston moves the air piston 15, compressing the spring 17. When the rod 18 moves backward, the working fluid above the piston 10 cavity under the action of the weight of the housing 8 and the clamp 7, as well as the accumulated energy of the spring 17 moves the ring 27 to the extreme position limited by the ring 28 and flows through the holes 25 of the cavity above the piston into the cavity under the piston. The ring 14 is designed to limit the movement of the air piston 15. Sealing rings 16 prevent the penetration of working fluid into the air chamber formed by the air piston 15, the cover 13 and the inner walls of the housing 8. Sealing rings 22 prevent penetration of the working fluid into the internal cavity of the rod 18.

The results of experimental studies have shown that when the gap changes, a significant change in local forces occurs. A series of experiments were conducted with the following input values:

- hydraulic device 6 of the transmission of forces according to a given algorithm, made according to the first embodiment;

- piston diameter 10 is 49 mm;

- gaps 0.03, 0.04, 0.05 and 0.25 mm;

- viscosity of working fluid ISO VG-10 (Mobil Velocite 6);

- Press model K3732.

With the gap value δ = 0.03 mm, the magnitude of the force was 23.4 tons, δ = 0.04 mm - 2.08 tons, δ = 0.05 mm - 1.28 tons and δ = 0.25 mm - 0, 33 tons.

The results of the experiment using a hydraulic device 6 for transmitting power according to a given algorithm, performed according to the second variant with a diameter of the inner hole of the ring 27 equal to 5 mm, are as follows: when the gap value Δ = 0.3 mm, the force amounted to 23.4 tons, Δ = 0, 38 mm - 2.08 tons, Δ = 0.47 mm - 1.28 tons and Δ = 2.04 mm -0.33 tons.

FIG. 18 and FIG. 19 shows the graphical dependences of the change in local forces on the size of the gap of the hydraulic device 6 for transmitting forces according to a predetermined algorithm, performed according to the first and second variants, respectively. Analysis of graphical dependencies showed that for a device manufactured in the first embodiment, the area of rational use lies in the range of forces from 0.5 tons to 2.5 tons, and for the device according to the second option - from 2 tons to 11 tons. Thus, it can be concluded that these devices can complement each other's work and be used in a differentiated clamping device, depending on the set conditions of the shaping process.

The positive effect from the application of the proposed technical solution is as follows. Managing the local efforts of pressing the workpiece to the matrix has a positive effect on the process of shaping, expands technological capabilities, allowing you to make parts from hard-to-deform materials, and also increases the accuracy of parts manufacturing. The compactness of the differentiated clamping device and the possibility of using a relatively simple and reliable governing body that can be manufactured for this part allows it to be installed in standard dies used on universal equipment.

Claims (4)

1. The method of sheet punching, including shaping the workpiece in the stamp sheet punching, containing the upper and lower plates, the matrix and the punch, characterized in that the stamp establishes a differential clamping device, made in the form of clamping sectors, mounted on a common plate, while in the process shaping the workpiece to regulate the flow and movement of the metal from the periphery to the zone of the deformation zone by controlling local forces in each of the sectors of the pressure of the said device in the algorithm. 2. Differential clamping device of a stamping sheet stamping, characterized in that it is made in the form of clamping sectors fixed on a common plate, each of the clamping sectors is equipped with a hydraulic device for transmitting local efforts according to a predetermined algorithm. 3. The device according to claim 2, characterized in that the hydraulic device for transmitting local forces according to a predetermined algorithm comprises a housing, a piston rod, and rings with an inner surface of variable cross-section, which with the peripheral surface of the piston form a gap changing with moving the piston relative to the housing. 4. The device according to claim 2, characterized in that the hydraulic device for transmitting local forces according to a given algorithm comprises a housing, a piston rod, the rod being hollow with radial holes, and a movable ring mounted on the piston, having the ability to block the holes in the piston The axis of variable section is installed in the housing, one end of which is made in the form of a piston placed in the cavity of the rod, while the movable ring with the axis of variable section forms a gap that changes as the hollow rod moves with piston and ring about an axis.

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