RU2438819C1 - Tube bending machine with bending mandrel with strain-resistant structure - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to tube bending processes. Proposed machine comprises extractor secured at machine rear part, piercing rod extending from extractor beyond machine front section whereat clamping female die is arranged to strain tube fitted in the mandrel by resultant force transmitted via piercing rod to extractor to resist resultant clamping response. Note here that tube bending machine comprises bearing structure shaped to have piercing rod lengthwise axis located to subject bearing structure solely to contracting forces.

EFFECT: ruling of bending strains.

8 cl, 8 dwg

Description

FIELD OF THE INVENTION

The present invention relates to pipe bending machines with a mandrel for bending, having a supporting structure, which is especially resistant to operating stresses.

State of the art

It is known that in a pipe bending machine with a mandrel for bending, the extracting device is fixed at the rear of the workplace of the machine, and the piercing rod extends longitudinally from the extracting device to the front of the machine, where the mandrel and clamping head equipped with a matrix are located. In existing bending machines, the workplace is fixed on a structure that is generally attached to the floor.

When the pipe to be bent, which is inserted into the mandrel, is clamped into the clamping head matrix, the pulling force, which is applied tangentially to the clamping head matrix, causes a reaction on the mandrel directed along the piercing rod, which is connected to the extraction device at its end opposite the mandrel.

In existing pipe bending machines with a mandrel for bending, the workplace of the machine is subject to essentially bending stresses, as a result of the force applied by the bending matrix to the workstation of the machine. These bending stresses, which propagate at the end of the machine structure from the bending matrix to the pipe to be bent and, in turn, from the latter to the mandrel and piercing rod, and again to the workplace of the machine through the extraction device, at its end, the opposite end, to which is fixed piercing rod, cause cyclic elastic deformation in the workplace, which cause curvature of the structure. When bending stresses become especially strong, mainly depending on the material, diameter and thickness of the pipe to be bent, elastic deformations become so high that they are no longer acceptable if they want to achieve good quality work and products.

Disclosure of invention

The present invention addresses these drawbacks.

In particular, it is an object of the present invention to provide a structure for a bending machine with a bending mandrel that is not subject to bending stresses when the pipe to be bent is subjected to traction by a clamping head matrix.

This task and others are achieved by means of a bending machine with a bending mandrel, which has a supporting structure, which is especially resistant to operating stresses, in which the extracting device is mounted on the rear of the bending machine, and the piercing rod continues with its longitudinal axis from the extraction device to the front of the machine, where the clamping head, which is equipped with a matrix, stresses the pipe to be bent, which is inserted into the mandrel, by the traction resulting force, which is transmitted about a piercing rod to an extracting device that counteracts the resulting fastening reaction, moreover, the pipe bending machine contains a supporting structure having such a profile that it contains the longitudinal axis of the piercing rod in such a way that the supporting structure is mainly subjected to compressive stresses.

The aforementioned pipe bending machine is particularly preferred since it is not subject to bending stresses, does not experience deformations of the supporting structure, which worsen its working condition and damage its products. Since this is the same supporting structure that balances the tangential force exerted on the die, the tube bending machine unloads essentially only its load on the floor, so it does not need to be fixed to the ground to prevent its deformation and increase its static properties.

Brief Description of the Drawings

The present invention will be described with reference to its preferred embodiments and the accompanying drawings, in which:

figure 1 is a perspective view of a first embodiment of a pipe bending machine having a mandrel for bending according to the present invention;

figure 2 is a schematic longitudinal section of the pipe bending machine shown in figure 1;

figure 3 is an enlarged view of a portion of the right end of the pipe bending machine shown in figure 2;

FIG. 4 is an enlarged view of a portion of the left end of the pipe bending machine shown in FIG. 2;

figure 5 is an enlarged cross-sectional view of the supporting structure of the pipe bending machine shown in figure 1;

6 is a dissected perspective view of a second embodiment, which is a round, supporting structure of a pipe bending machine according to the present invention;

FIG. 7 is a perspective view of a third embodiment, which is a mesh supporting structure of a pipe bending machine according to the present invention;

Fig. 8 is a perspective perspective view of a third mesh embodiment of a supporting structure without a pipe bending machine.

Description of preferred embodiments of the invention

Firstly, with reference to FIGS. 1 and 2, a perspective view and a schematic longitudinal section, respectively, of a first embodiment of a supporting structure of a bending machine with a bending mandrel according to the present invention are shown. Figures 1 and 2 show a first embodiment of a supporting structure that has a prismatic or box-shaped shape and is indicated by 1. At the rear end of the supporting structure 1 (on the left in FIG. 2), the extraction device is generally indicated by 2 and the front end (on the right) figure 2) has a front frame 3.

The supporting structure is supported by the rear and front support elements 4 and 5, respectively. Accordingly, the front support member 5 projects forward by a step 6, on which the clamping head 7 rests.

As shown in detail in FIG. 3, which is an enlarged view of the clamping head 7, the clamping head 7 is provided with a matrix 8, which has a clamping device 9. The clamping device 9 is the subject of another patent application of the same applicant. The clamping head 7 is mounted with the possibility of sliding on the ledge 6 by means of guides 10, which are located horizontally on the same ledge. The clamping head 7 is in contact with the support element 11, which is mounted on the front frame 3 of the supporting structure 1. The supporting element 11 forms a transverse sliding connection between the supporting structure 1 and the clamping head 7.

The bending mandrel 12, which is mounted on the end of the piercing rod 13, will not be described hereinafter, since it is the subject of a previous patent application by the same applicant. The pipe T to be bent is located on the bending mandrel 12. The pipe T is supported by a holder 14 of a mandrel of a known type, which is shown in FIG. 1, but not shown in FIGS. 2 and 3 for clarity.

The extraction device 2 is best shown in FIG. 4, which is an enlarged view of a portion of the left end of the machine. The extracting device is known and therefore is not further described. However, the extraction device is not installed at one end in the workplace, as in existing bending machines, and according to the invention, the extraction device is located in the anchor plate 15, passing through it. An anchor plate 15 of the extracting device 2, which is suitably reinforced with a stiffening rib 16, is mounted on the rear frame 17 as the rear of the supporting structure 1 in such a way that the holding force that is applied by the extracting device 2 against the traction applied by the matrix 8 is unloaded only the supporting structure 1. Therefore, preferably, the supporting structure 1 has a rear frame 17 that surrounds the extraction device 2, at least to a large extent, but preferably in personality. For this reason, it is particularly preferable that the rear of the supporting structure is in the form of a frame, similar to the front frame 3.

In this first embodiment of the present invention, the supporting structure 1 of the bending machine with a mandrel for bending has a prismatic or box-shaped. The supporting structure has side walls 18, 19, 20, 21. Lifting sleeves are shown, indicated by 22. In FIGS. 1, 2, 4, openings for accessing the supporting structure 1 are generally indicated by 23.

As can be seen below, some parts of the supporting structure 1, for example, which relate to the side walls, can be removed. However, it is assumed that all the interacting parts of the supporting structure are subjected to stress in order to counteract the traction exerted by the matrix in a pipe-bending operation. In other words, the resulting traction forces exerted by the clamping head and the resulting retention forces exerted by the extracting device 2, which has the g axis of the piercing rod 13 as the application direction, are transmitted inside the profile bounded by the front frame 3 and the rear frame 17 of the supporting structure 1, so as the profile of the supporting structure 1 contains inside the piercing rod 13. Such resulting forces transmitted through the piercing rod 13 determine the compressive stress on the supporting structure 1. However, the bearing cantilever ruktsiya has a geometric cross section, having a center bit axis than g piercing rod where existing efforts transmitted.

In fact, usually, in order to bend the pipe in an arc of 180 ° with a reduced bending radius, the mandrel 12 with the assembly that supports it, and therefore the pipe T are not centrally located inside the box-shaped supporting structure 1. Obviously, when traction is applied by the matrix to the tube T, resulting in opposing forces exerted by the box structure, has a direction that usually does not coincide with the direction of traction.

For clarification, reference is made to FIG. 5, which is a cross section of the supporting structure 1, in its first box-shaped embodiment. The cross section is essentially rectangular, and it can be noted that the geometric center of the section, that is, the center C, does not coincide with the point G, which is the intersection point of the axis g of the piercing rod 13 in the section.

In order for the resultant applied force to coincide with the resultant resistance forces in the supporting structure 1, the moment of inertia of the section resistance can be changed, for example, by using a reinforcing plate 24 so that the center of inertia coincides with the intersection point G of the g axis of the piercing rod 13.

With reference to FIG. 6, a perspective view is shown, which is longitudinally dissected by a vertical plane of symmetry passing through the g axis of the second embodiment of the supporting structure, which is particularly resistant to operating stresses. In this drawing and in the subsequent drawings, the same reference numbers are used to denote the same or similar elements. The supporting structure in the second embodiment is a round pipe and is indicated by 25, and has a front frame 3 and a rear frame 17, as in the first embodiment. If the extraction device 2 is centrally located inside the supporting structure, the supporting structure acts in such a way as to balance, first of all, the force exerted on the pipe to be bent, since the force exerted on the pipe by the clamping head is unloaded onto the round tubular structure by means of a vertical support clamping head 7 on the front frame 3.

In this case, only the axial load is distributed over the entire thrust section of the supporting structure without the formation of large deformations and vibrations of the supporting structure, so that the defects caused during processing depend on the bending operation.

With reference to FIG. 7, there is shown a perspective view that is longitudinally dissected by a vertical plane of symmetry passing through the g axis, a third embodiment of the supporting structure according to the present invention. The supporting structure of the third embodiment is generally mesh and is indicated by 26, and has a front frame 3 and a rear frame 17, as in the first embodiment. If the extraction device 2 is located centrally inside the supporting structure, the supporting structure acts in such a way as to balance, first of all, the force applied to the pipe to be bent, since the force applied to the pipe by the clamping head is unloaded onto the mesh structure by means of the vertical clamping support heads 7 on the front frame 3.

The persistent parts of the mesh structure, which are essentially beams, generally indicated by 27, which are located at the corners of the structure, form a frame and walls may not be present. The wall portion 28 may function as a reinforcing plate 24, which is described in the first embodiment and shown in FIG.

Stiffeners and stiffeners for beams 27 are desirable in order to obtain the same reaction of the supporting structure 26, which is shown in more detail in a general perspective view in Fig. 8, for which a pipe bending machine with a mandrel for bending is not shown. As can be seen in Fig. 8, there are support elements 29 for guides 10 for supporting and sliding the clamping head, and a milled region 30 on which the supporting element 11 for the clamping head 7 is mounted.

From the foregoing, it is clear that the supporting structure according to the invention may have solid side walls, as in the first and second embodiment, or not solid, when it has a frame and mesh side walls, as in the third embodiment. Of course, the supporting structure will also have a different polygonal cross section. If the cross section is round, it can be round or oval.

In any case, it is preferable that the supporting structure has a cross section having such a moment of inertia that the pulling force exerted by the matrix has a direction passing through the center of inertia of the cross section.

In accordance with the fact that the system of existing efforts in the bending operation is such as to create only compression stresses, it is enough that the supporting structure simply rests on the floor, without fixing it.

An additional advantage is due to the fact that the clamping head is slidably mounted on the front end on guides arranged horizontally on a ledge resting on the ground transversely to the longitudinal direction, the clamping head in contact with the support element at the front end of the supporting structure, wherein the support element forms a connection with sliding with the front end of the supporting structure. Thus, useless bending stresses on the supporting structure close to the clamping head are eliminated.

The advantages of the supporting structure according to the present invention are even greater. It should be understood that due to the optimal use of the metal material, which works in compression, the supporting structure of the described type allows to reduce the production costs of a pipe bending machine, since it requires less material compared to existing pipe bending machines.

An additional advantage is represented by the fact that the supporting structure according to the invention is more capable of undergoing a change in its length if it is necessary to process the pipes for substantial elongation. In fact, in a bending machine with a mandrel for bending the prior art, if the length of the workplace has increased, the deformations caused by bending during processing will also increase. On the contrary, with the supporting structure according to the present invention, if the workplace is extended in length, it does not undergo a noticeable increase in deformation. As a positive consequence, in the modular use approach, it is necessary to add a section of the supporting structure in order to increase the length of the workplace and provide bending operations for pipes having the required length.

In the foregoing description, illustrative and non-limiting embodiments of the invention have been defined as defined in the appended claims.

Claims (8)

1. A pipe bending machine with a mandrel for bending, having a supporting structure that is especially resistant to operating stresses, the extracting device (2) which is fixed at the rear of the pipe bending machine, and the piercing rod (13) extends with its longitudinal axis (g) from the extracting device behind the front part of the machine, in which the clamping head (7), equipped with a matrix (8), stresses the pipe (T) to be bent, which is inserted into the mandrel (12), by the traction resulting force, which is transmitted through the piercing rod (13) to the extracting a device (2) that counteracts the resulting fastening reaction, characterized in that it contains a supporting structure (1; 25; 26), inside the profile of which is located the longitudinal axis (g) of the piercing rod (13) so that the supporting structure (1; 25; 26) is mainly affected by compressive stresses. 2. The machine according to claim 1, characterized in that the supporting structure (1) is prismatic. 3. The machine according to claim 1, characterized in that the supporting structure (25) has a circular cross section. 4. The machine according to claim 1, characterized in that the supporting structure (26) is a mesh structure. 5. The machine according to claim 1, characterized in that the supporting structure (1; 25; 26) has a cross section with such moment of inertia that the traction force applied by means of the matrix (8) has a direction passing through the center of inertia of the cross section. 6. The machine according to claim 1, characterized in that the supporting structure (1; 25; 26) is supported on the floor by the front and rear support elements (4, 5). 7. The machine according to claim 1, characterized in that the clamping head (7) is mounted so that it can slide on the front end on guides (10, 10) located horizontally on a ledge (6), resting on the ground, transverse to the longitudinal direction of the machine, the clamping head (7) is in contact with the support element (11) in the front of the supporting structure (1; 25; 26). 8. The machine according to claim 1, characterized in that the supporting element (11) forms a connection with transverse sliding.

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