RU2691478C1 - Bending method of long hollow articles with open type profile - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to metal forming and can be used in production of bent lengthy profiles of open type. Inside the workpiece a set of inserts is placed and workpiece and inserts are jointly bent. Set of inserts from steel strips is installed in each of the open cavities of the workpiece with the possibility of longitudinal displacement of each of the strips relative to each other and accordingly relative to the workpiece during bending. Insert is placed in the open cavity of the workpiece along the whole length of the profile, and billet with a set of inserts is bended in rollers. Profile bending is carried out in zone of plastic deformations, and bending of steel strips in area of elastic deformations.EFFECT: higher stability of profile due to elimination of corrugation.1 cl, 3 dwg

Description

Bending method of long hollow products with an open profile

The invention relates to the processing of metals by pressure and can be used in various areas of industry in the manufacture of curved long profiles of the open type.

The following methods are known for bending profiled products.

Patent RU No. 1417281, dated 07.03.1986 “Mandrel for bending pipes”. The method is implemented using a specialized bending mandrel. Bending of the pipe is carried out by pulling through the top and bottom of the matrix with the profile of the bent pipe and the bending mandrel located between them. The mandrel contains sections of elastic filler, carrying at the end of an elastic step washer, a metal gauge insert with a groove for accommodating a step washer and with a shank for accommodating sections of elastic filler. The elastic filler is flexibly connected with a multi-element bending assembly. Bending is carried out by pulling through the matrix of the metal calibrating insert acting on the front edge of the workpiece with the simultaneous oscillatory movement.

SU patent No. 1433546, dated 10.30.1988 “Device for bending tube blanks”. The method of flexible billet, implemented by the device, consisting of a flexible mandrel, a split matrix with a curved channel, a hollow pusher and a mechanism for creating pressure in a flexible mandrel. The flexible mandrel is made in the form of rigid links pivotally connected to one another and installed inside an elastic sleeve and an emphasis pivotally connected to the lower extreme rigid link. The device is designed to produce a single-bend, steep-bend branch pipe with a high radius of curvature and implements the method of bending tubular blanks as follows. An elastic mandrel is inserted into the hole of the tube blank. When pressure is applied, the rigid links compress the elastic sleeve, stretching the tube stock in the circumferential direction and creating internal pressure preventing its loss of stability. Then push the billet through a split matrix and this form the part.

The disadvantages of these methods are the complexity of their implementation and the high cost of the mandrel.

Patent RU 2245206 dated January 27, 2005 “Method of bending pipes”. The method consists in inserting a filler into the tube cavity, bending it by pulling along the bending and auxiliary rollers and removing the filler. As a filler, a cable is used, introduced to ensure constant contact of its surface with the inner surface of the pipe, and profiled rollers are used as bending rollers, one of which is pressurized and the other spring-loaded.

The disadvantage of this method is the difficulty of extracting the cable from a bent pipe and a significant complication of equipment in the case of this method when bending the profile with an open loop.

SU patent No. 1692708, dated 11/23/1991 “Mandrel for bending pipes”. The method is based on the use of a mandrel containing a hollow rod, on which a flexible container with a filler is movably mounted. The mandrel is introduced into the bending zone, the cradle is fixed in place, the container is pushed to the inlet end of the blank by the movement of the hollow rod, the filler is moved into the pipe in the bending zone, then the hollow rod is fixed, the cradle is released to the inlet end of the workpiece. flexible and fasten the motionless.

Disadvantages of the method: when using sand as a filler, there is insufficient elasticity of impact on the pipe walls, which leads to a change in the geometry of the pipe cross section at bending places, when using polyethylene balls as a filler, their rigidity is low, which leads to the pipe ovality at bending points, Also difficult returning polyethylene balls back to the container due to loss of the geometry of the pipe walls in places of bending of the filler. Moreover, when bending an open profile because of the impossibility to ensure uniform distribution of the filler pressure on the inner walls with an open section of the profile, the formation of the corrugations is not excluded.

A common disadvantage of the above methods is that they are designed for bending closed-type profiles in the form of pipes and cannot be used for bending open-type profiles.

The closest to the claimed method, the tasks to be solved, is the method described in RU patent No. 2262404, dated 10/20/2005 "Method of bending lengthy products with an open type profile", consisting in placing a filler from an elastic material inside the workpiece. In preparation for bending long, hollow articles with an open profile, a filler made of a solid elastic material is placed inside the blank. The filler is identical in shape and size to the shape and dimensions of the inner cavity of the blank and is formed from a set of long inserts longitudinally oriented along the blank, each of which is not thick. exceeds the width of the open part of the workpiece. In the process of bending, which is carried out on a three-roll bending machine, the filler moves along with the workpiece and, deforming and slipping along the walls, provides the necessary pressure on the walls of the workpiece, excluding the formation of corrugations.

The disadvantages of this method include the following: the use of an elastic material as a filler leads to the fact that in some cases the size of the backwater may be insufficient to prevent bumps on the product, the loss of stability of the sectional billet in cross section is not prevented and possible bending radii are limited.

The basis of the invention is the task of improving the method of bending lengthy hollow products with an open profile, for increasing the possible bending radii to avoid buckling in the form of corrugations.

The task is solved by the fact that in the method of bending lengthy hollow products with an open profile, including placing inside the workpiece a set of inserts and joint bending of the workpiece and inserts in each of the open cavities of the workpiece, a set of inserts of steel strips are installed with the possibility of longitudinal displacement of each of the strips each other, and accordingly with respect to the workpiece in the process of bending, the workpiece bending with a set of inserts is produced on rolls made in the form of rollers with the width of the working part between the edges ichitelyami equal width with the workpiece placed therein inserts, the bending of the profile is carried out in the zone of plastic deformation and bending of the steel strips in the region of elastic deformation, which increases the stability of the preform to form the corrugations.

FIG. 1 shows the installation of steel inserts in the open profile type; FIG. 2 - installation of prefabricated billet in a bending machine; FIG. 3 - section AA of FIG. 2, with the location of the prefabricated workpiece in the rolls of the bending machine.

The method of bending of long hollow products with an open profile is as follows.

Between the shelves of profile 2 is placed inset 1, recruited from steel strips. The height of the insert 1 must correspond to the gap between the flanges of the profile 2, and the thickness of the steel strips is chosen from those considerations so that each individual strip, when the profile 2 bends, is deformed in an elastic region. The width of steel strips B is chosen so that the width of the prefab profile 2 under bending (a profile with sets of steel plates installed between its shelves) generally exceeds the width A of profile 2. A lubricant is applied between the steel plates of the insert 1 and between the plates and the profile 2, to ensure shear plates, both among themselves and relative to the shelves of the profile 2 when it is bent.

Rolls 3 and 4 three-roll bending machine made in the form of rollers. The width of the inner profile of the roll 3 corresponds to the width of the prefabricated billet B of the profile 2 for bending. The presence of external stops on the rolls 3 contributes to a better positioning of the prefab, ensure its direction and orientation, prevent its curvature in the longitudinal direction.

In the process of bending, which is carried out on a three-roll bending machine, a set of steel plates installed in the cavity between the shelves of profile 2, bending in an elastic area, provides the necessary backing to the wall of profile 2 and prevents the formation of bumps and folds on them. To compensate for the difference in elongation on the outer and inner surfaces of the bend, the steel strips in the inset insert have the ability to move relative to each other in the longitudinal direction. Since steel plates work only in the elastic region, they are rather easily removed from the cavities between the flanges of profile 2 and can be reused.

This method allows you to get bent lengthy open profiles, with repeated use of tooling.

Literature.

1. Rospatent, www.fips.ru,

2. United States Patent and Trademark Office (USPTO, www.uspto.gov)

3. European Patent Office (EPO, worldwide.espacenet.com)

4. World Intellectual Property Organization

(www.wipo.int).

Claims (1)

The method of bending lengthy hollow products with an open profile includes placing inside a set of inserts and joint bending of the workpiece and inserts, characterized in that a set of inserts of steel strips is installed in each of the open cavities of the blank, with the possibility of longitudinal displacement of each of the strips relative to each other and respectively, relative to the workpiece in the process of bending, the insert is placed in the open cavity of the workpiece along the entire length of the profile, and the bending of the workpiece with a set of inserts is produced on a roll x, made in the form of rollers with the width of the working part between the stops, equal to the width of the workpiece with the inserts placed in it, the profile being flexible in the zone of plastic deformations, and the steel bands are bending in the area of elastic deformations.

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