RU2847948C1 - Stamp for extracting large-sized parts - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metal forming, in particular to stamping equipment for drawing body parts. The stamp contains a punch, a die and a clamp. The die and the press are made with draw ribs with rounded edges and with notches for the draw ribs, which have a trapezoidal shape. The draw ribs on the working end of the die and the draw ribs of the press are made double. The double ribs are equidistant from each other and face in opposite directions. One of them is made on the clamp, and the second is made on the die with an offset relative to the rib on the clamp. The side walls of the notches are made along the radius.

EFFECT: more uniform distribution of working stresses on the braking elements of the die and in the blank itself, which reduces scrap when drawing large parts.

1 cl, 1 dwg

Description

The invention relates to cold sheet metal stamping using double or single action drawing dies.

A drawbar is a technological element of the die design, the primary purpose of which is to decelerate the workpiece during drawing. The classic drawbar design consists of a round projection from the die and clamping tooling and is widely used in stamping. Drawbars enable the production of high-quality parts, providing the necessary and sufficient tension to prevent the formation of facial defects and corrugations. When manufacturing large automotive parts, a double row of drawbars is often used, with a minimum distance of 10 mm between them. This requires increasing the workpiece size to ensure a secure grip by the drawbars. This increases the service life of the die tooling, preventing rapid rib wear and, consequently, frequent die maintenance. The position of the ribs in the die tooling determines the workpiece deceleration pattern.

A drawing die is known from the prior art, comprising a punch, a matrix with draw-down ribs, a clamp with recesses for the draw-down ribs for performing additional tangential stretching of the flange of the workpiece and a mechanism for removing the stamped drawn semi-finished products from the die, which is made with longitudinal strips located outside the clamping surface of the clamp, and with transverse strips located in grooves made in the recesses of the clamp for the draw-down ribs [Patent of the Russian Federation No. 2631070, Stamp for drawing large-sized parts, published 09.14.2017, Bulletin No. 26].

This type of die enables a drawing operation with metal flow inhibition, but at the same time, a large technological allowance is obtained; when the metal is pinched, there is a high probability of the appearance of sink marks due to the limited and uneven deformation, significant load on the die elements and a change in the clamping force due to wear of the drawing ribs and corresponding recesses.

A design of rectangular drawbar ribs with radius roundings and recesses of the corresponding shape for them is known [RU Patent No. 2627318, Method for drawing body parts and a stamp for its implementation, published 05/31/2017. Bulletin No. 16; RU Patent No. 2201930, Stamp for drawing parts of complex shape, published 04/10/2003].

This design of the tension ribs leads to significant stress concentration in both the tooling and the parts, which negatively impacts the performance of the die and the quality of the products.

Also known is a die for drawing body parts, selected as a prototype, which comprises a punch, a matrix with drawing ribs with rounded edges at the working end, and a clamp with recesses for the drawing ribs. The recesses on the clamp are made with inclined side walls, located tangent to the radius sections of the drawing rib and to the surface of the clamp at an angle of 45°. The recesses on the clamp for the drawing ribs are made of a triangular or trapezoidal shape. The technical result is that such a die design allows for an increase in the degree of braking of the flange of the workpiece and savings in rolled metal due to the reduction of technological allowances on the surface of the clamp and braking of the workpiece, and also makes it possible to implement differentiated braking of the flange of the workpiece, which improves the quality of the product [Patent of the Russian Federation No. 2072270, Die for Drawing Body Parts, published. [27.01.1997].

In this die, the single-row braking elements bear significant loads, which reduces the tooling's service life. Significant stress and deformation also occur in the workpiece, which can still lead to defects.

The technical problem solved by the claimed invention is to increase the service life of the stamp and the quality of the drawing.

The technical result achieved with the aid of the claimed invention is the optimization of the workpiece braking scheme during the drawing of large-sized parts with a more uniform distribution of operating stresses on the braking elements of the die and in the workpiece itself with a reduction in defects.

The said technical result is achieved by a stamp design comprising a punch, a matrix and a clamp, the matrix and the clamp are made with drawbars with rounded edges and with recesses for the drawbars, which have a trapezoidal shape, wherein the drawbars of the matrix, which are located on its working end, and the drawbars of the clamp are made double, the said drawbars from the double drawbars are located equidistantly relative to each other and are oppositely directed, wherein one of them is made on the clamp, and the second - on the matrix with an offset relative to the drawbar on the clamp, and the side walls of the recesses for the drawbars are made along the radius.

The use of double draw ribs ensures more reliable braking of the metal during drawing, distributing the load on them.

The arrangement of the tension ribs equidistant from each other ensures the equalization of braking forces and improves the technological efficiency of tooling production.

Oppositely directed drawbars redistribute the braking forces between the die and clamp, equalizing the operating stresses in the tooling's load-bearing elements and allowing them to be moved closer together, resulting in a reduction in manufacturing allowance. Alternating the direction of the drawbars, one opposite the other, evenly distributes the load on the die tooling and reduces the distances between the drawbars, thereby reducing the workpiece size and providing the necessary forces for drawing the part without increasing the frequency of die maintenance.

The implementation of one tension rib on the clamp and the other on the matrix with an offset relative to the rib located on the clamp equalizes the load on the elements of the press tooling, without significantly increasing the technological allowance.

Making the side walls of the recess radial creates additional distributed friction zones, increasing the actual number of tension ribs to four at the pressure points.

The proposed design of the die tension rib will ensure a reduction in the metal content of the blank for the production of large-sized front and internal parts without loss of quality of the resulting part, since it provides the necessary and sufficient tension of the blank for the production of high-quality large-sized automobile parts.

The stamping device is illustrated by drawings, where Fig. 1 shows a section of the stamp at the location of the drawbars and a diagram of the workpiece clamping with the parameters of the drawbars used, which determine the braking diagram for the workpiece for drawing out the part.

The drawing die (Fig.) comprises a punch (not shown), a matrix 1 and a clamp 2. A product 3 of thickness S is clamped between them. The matrix 1 is provided with a constriction rib 4 with a rounded profile of radius R ₂ . The clamp is provided with a constriction rib 5 with a rounded profile of radius R ₃ . Opposite the constriction rib 5 there is a trapezoidal recess 6, the side walls of which are rounded with radius R ₄ . Opposite the constriction rib 4 there is a recess 7, also trapezoidal, the side walls of which are rounded with radius R ₁ . The parameters of the ribs R _i can be changed depending on the technical specifications. The transitions between the constriction ribs 4 and 5, the side walls of the recesses 6 and 7 and the flat sections of the matrix 1 and the clamp 2 are made with radii r ₁ , r ₂ , r ₃ , r ₄ . The constriction ribs 4 and 5 are located equidistant from each other along the entire perimeter of the stamp, offset from each other, while the side walls 8 of the recesses 6 and 7 are opposite each other.

The die operates as follows. Before drawing, blank 3 is clamped onto die 1 by clamp 2. To secure the blank material around its perimeter, it is deformed by draw ribs 4 and 5, which force the material from blank 3 into recesses 6 and 7. This causes distributed clamping of the material along the side walls of the recesses, including the space between draw ribs 4 and 5. In effect, side walls 8 form two additional draw ribs by directing the lines of action of the pressure forces from their side into the depressions formed by radial transitions _r1 and _r3 .

The drawbar can be manufactured as a single, integral element of the die clamp and matrix, or as two insertable ribs. The direction of the drawbars can be varied depending on the technical specifications and the wear resistance requirements of the die.

Claims (1)

A stamp for drawing out body parts, comprising a punch, a matrix and a clamp, characterized in that the matrix and the clamp are made with drawbars with rounded edges and with recesses for the drawbars, which have a trapezoidal shape, wherein the drawbars of the matrix, which are located on its working end, and the drawbars of the clamp are made double, the said drawbars of the double drawbars are located equidistant from each other and are oppositely directed, wherein one of them is made on the clamp, and the second - on the matrix with an offset relative to the drawbar on the clamp, and the side walls of the recesses for the drawbars are made along the radius.