GB2178350A

GB2178350A - Device for cold forming bodies, especially helical bodies

Info

Publication number: GB2178350A
Application number: GB8518916A
Authority: GB
Inventors: Josef Svercl; Jan Novak; Stepan Zampach
Original assignee: Sigma Koncern
Current assignee: Sigma Koncern
Priority date: 1983-03-14
Filing date: 1985-07-26
Publication date: 1987-02-11
Also published as: FR2585594B3; SE8503619D0; DE3527664A1; GB8518916D0; SE448069B; FR2585594A1; NL8502199A; CS245208B1; CS8301722A

Abstract

A body accommodates a block (3) provided with a guiding cavity (4) formed by a system of part-cylindrical surfaces (10) for guiding forming jaws (5) for forming the bodies. The cavity is tapered outwardly from the workpiece inlet end. The jaws (5) have internal profiles to produce helically corrugated tubing, round or out-of-round bar or tubing or bars of longitudinally-varying cross-section. <IMAGE>

Description

SPECIFICATION Device for cold forming bodies especially helical bodies The invention relates to a device for cold forming bodies, especially helical bodies made of bare seamless pipes, e.g. to produce rotors for single-spindle pumps.

There is known e.g. a device for cold forming of spindles of single-spindle pumps according to Czechoslovak Patent No. 136 995, which comprises longitudinally divided forming jaws seated slidably in a conical cavity and controlled by means of a press.

However, the conical guiding of the forming jaws is not advantageous, as the contact of the jaws with the conical surface is a linear one, so that at the point of contact high specific pressures take place, the jaws are quickly worn out, they are exposed to bending forces and they break, or fissures are formed in them.

Some of the mentioned drawbacks of the hitherto known devices may be obviated by a device according to the invention, comprising a body, in which forming jaws are situated which define a functional cavity, the body being provided with a tapered guiding cavity for guiding the forming jaws, the guiding cavity being defined by a system of part-cylindrical surfaces.

In a preferred embodiment of the invention the part-cylindrical surfaces are inclined at an angle corresponding to the top angle of an imaginary cone, on the lateral surface of which the axes of the part-cylindrical surfaces lie, and the number of the part-cylindrical surfaces corresponds to the number of the forming jaws and the axis of the cone coincides with the axis of the functional cavity defined by the forming jaws.

One of the advantages of the invention may be seen in the fact that the change of the local loading of the external surfaces of the forming jaws into a flat loading obviates bending stress of the jaws and reduces considerably their wear thus extending their service life.

In order that the invention may be clearly understood and readily carried into effect, a preferred embodiment thereof will now be described, by way of exaple, with refernce to the accompanying diagram matic drawings, in which: Figure 1 shows an axial section of the device; Figure 2 shows an axonometric view of a block with a guide cavity; Figure 3 shows an axonometric view of one of the forming jaws; and Figure 4 shows a cross-section of the system of forming jaws.

A device according to the invention for cold forming of helical bodies, e.g. rotors of single-spindle pumps, comprises a body 21 formed by a box 1 which is fixed onto a base plate 2. In the box 1 is slidably seated a block 3. The block 3 is provided with a guiding cavity 4 for guiding forming jaws 5. The block 3 is also provided with recesses 6 for functional engagement with keys 7, which transmit the force from a press (not shown) and make the block 3 move axially in the direction to the outlet side of the box 1. The reverse motion of the block 3 is secured by springs 8 anchored in blind holes 9 in adjacent walls of the block 3 and box 1. For handling the block 3 or forming jaws 5, the wall of the box 1 on the outlet side is removable.

The cavity 4 in the block 3 is formed by a system of converging part-cylindrical surfaces 10, the inclination of which is determined by a top angle oc of an imaginary cone 11, on the lateral surface 12 of which the axes of the part-cylindrical surfaces 10 lie. The number of the part-cylindrical surfaces 10 corresponds to the number of the forming jaws 5 used.

The outer portion of each forming jaw 5 is delimited by a part-cylindrical surface 13 and the inner portion by a part-helical surface and two converging planar surfaces 14, which are defined by two planes which make with each other an angle ss = 360 : x, where x is the number of the forming jaws 5, and intersect in the axis 15 of the cone 11. End faces 16 of the forming jaws 5 are parellel to end faces 17 of the block 3 and they lean against internal surfaces of the walls of the box 1. The part-helical surfaces of the forming jaws 5 define a helical functional cavity 18 situated in the axis 15 of the cone 11.

The position of the forming jaws 5 on the part-cylindrical surfaces 10 is locked against turning during their opening by means of a key or feather 20 seated in a recess 19 either directly in the part-cylindrical surface 10 of the cavity 4 or (not shown) on the face 16 of the forming jaws 5. The forming jaws 5 together with the cavity 4 in the block 3 are advantageously orientated with an incline to the outlet side of the box 1.

The box 1 is provided on the inlet side with an inlet hole 28 and a guide bush 23 having a cavity for guiding the pipe 33 being formed and on the outlet side with an outlet hole 29, and a nut 30, which is fixed from outside to the removable wall of the box 1 and provided with a helical guide projecting out of the nut 30, by means of which the feeding and turning of the formed pipe 33 may be secured.

The device may also be used e.g. for the reduction of a round and out-of-round cross-section of a solid bar or pipe, for the production of e.g. non-helical bars of variable cross-section in the longitudinal direction or non-round cross-section of a semi-product of a round cross-section, etc. The invention may even be used in cases, when the cavity for guiding the forming jaws is made directly in the box of the body. The system of part-cylindrical surf may be represented both by a system of rotating cylindrical surfaces and by a system of non-rotating cylindrical surfaces formed e.g.

by plane surfaces.

1. Device for cold forming of bodies, especially helical bodies made of seamless pipes, e.g. of rotors of single-spindle pumps, the device comprising a body in which forming jaws are situated which define a functional cavity, the body being provided with a tapering guiding cavity for guiding the forming jaws, wherein the guiding cavity is defined by a system of part-cylindrical surfaces 2. Device according to Claim 1, wherein the part-cylindrical surfaces are inclined at an angle corresponding to the top angle of an imaginary cone, on the lateral surface of which the axes of the part-cylindrical surfaces lie, and the number of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Device for cold forming bodies especially helical bodies The invention relates to a device for cold forming bodies, especially helical bodies made of bare seamless pipes, e.g. to produce rotors for single-spindle pumps. There is known e.g. a device for cold forming of spindles of single-spindle pumps according to Czechoslovak Patent No. 136 995, which comprises longitudinally divided forming jaws seated slidably in a conical cavity and controlled by means of a press. However, the conical guiding of the forming jaws is not advantageous, as the contact of the jaws with the conical surface is a linear one, so that at the point of contact high specific pressures take place, the jaws are quickly worn out, they are exposed to bending forces and they break, or fissures are formed in them. Some of the mentioned drawbacks of the hitherto known devices may be obviated by a device according to the invention, comprising a body, in which forming jaws are situated which define a functional cavity, the body being provided with a tapered guiding cavity for guiding the forming jaws, the guiding cavity being defined by a system of part-cylindrical surfaces. In a preferred embodiment of the invention the part-cylindrical surfaces are inclined at an angle corresponding to the top angle of an imaginary cone, on the lateral surface of which the axes of the part-cylindrical surfaces lie, and the number of the part-cylindrical surfaces corresponds to the number of the forming jaws and the axis of the cone coincides with the axis of the functional cavity defined by the forming jaws. One of the advantages of the invention may be seen in the fact that the change of the local loading of the external surfaces of the forming jaws into a flat loading obviates bending stress of the jaws and reduces considerably their wear thus extending their service life. In order that the invention may be clearly understood and readily carried into effect, a preferred embodiment thereof will now be described, by way of exaple, with refernce to the accompanying diagram matic drawings, in which: Figure 1 shows an axial section of the device; Figure 2 shows an axonometric view of a block with a guide cavity; Figure 3 shows an axonometric view of one of the forming jaws; and Figure 4 shows a cross-section of the system of forming jaws. A device according to the invention for cold forming of helical bodies, e.g. rotors of single-spindle pumps, comprises a body 21 formed by a box 1 which is fixed onto a base plate 2. In the box 1 is slidably seated a block 3. The block 3 is provided with a guiding cavity 4 for guiding forming jaws 5. The block 3 is also provided with recesses 6 for functional engagement with keys 7, which transmit the force from a press (not shown) and make the block 3 move axially in the direction to the outlet side of the box 1. The reverse motion of the block 3 is secured by springs 8 anchored in blind holes 9 in adjacent walls of the block 3 and box 1. For handling the block 3 or forming jaws 5, the wall of the box 1 on the outlet side is removable. The cavity 4 in the block 3 is formed by a system of converging part-cylindrical surfaces 10, the inclination of which is determined by a top angle oc of an imaginary cone 11, on the lateral surface 12 of which the axes of the part-cylindrical surfaces 10 lie. The number of the part-cylindrical surfaces 10 corresponds to the number of the forming jaws 5 used. The outer portion of each forming jaw 5 is delimited by a part-cylindrical surface 13 and the inner portion by a part-helical surface and two converging planar surfaces 14, which are defined by two planes which make with each other an angle ss = 360 : x, where x is the number of the forming jaws 5, and intersect in the axis 15 of the cone 11. End faces 16 of the forming jaws 5 are parellel to end faces 17 of the block 3 and they lean against internal surfaces of the walls of the box 1. The part-helical surfaces of the forming jaws 5 define a helical functional cavity 18 situated in the axis 15 of the cone 11. The position of the forming jaws 5 on the part-cylindrical surfaces 10 is locked against turning during their opening by means of a key or feather 20 seated in a recess 19 either directly in the part-cylindrical surface 10 of the cavity 4 or (not shown) on the face 16 of the forming jaws 5. The forming jaws 5 together with the cavity 4 in the block 3 are advantageously orientated with an incline to the outlet side of the box 1. The box 1 is provided on the inlet side with an inlet hole 28 and a guide bush 23 having a cavity for guiding the pipe 33 being formed and on the outlet side with an outlet hole 29, and a nut 30, which is fixed from outside to the removable wall of the box 1 and provided with a helical guide projecting out of the nut 30, by means of which the feeding and turning of the formed pipe 33 may be secured. The device may also be used e.g. for the reduction of a round and out-of-round cross-section of a solid bar or pipe, for the production of e.g. non-helical bars of variable cross-section in the longitudinal direction or non-round cross-section of a semi-product of a round cross-section, etc. The invention may even be used in cases, when the cavity for guiding the forming jaws is made directly in the box of the body. The system of part-cylindrical surf may be represented both by a system of rotating cylindrical surfaces and by a system of non-rotating cylindrical surfaces formed e.g. by plane surfaces. CLAIMS

1. Device for cold forming of bodies, especially helical bodies made of seamless pipes, e.g. of rotors of single-spindle pumps, the device comprising a body in which forming jaws are situated which define a functional cavity, the body being provided with a tapering guiding cavity for guiding the forming jaws, wherein the guiding cavity is defined by a system of part-cylindrical surfaces

2. Device according to Claim 1, wherein the part-cylindrical surfaces are inclined at an angle corresponding to the top angle of an imaginary cone, on the lateral surface of which the axes of the part-cylindrical surfaces lie, and the number of the part-cylindrical surfaces corresponds to the number of the forming jaws and the axis of the cone coincides with the axis of the functional cavity defined by the forming jaws.

3. Device according to Claim 1 constructed, arranged, and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawings.