IE44973B1 - Deformation of a hollow metallic object - Google Patents

Description

In the first place, the invention relates to a method for cold deformation of a hollow metallic object by exerting an axially directed compressive force upon said object and by allowing a liquid pressure to act upon the wall of the object, so fiat the object will be deformed against the walls of a die, the liquid pressure being generated by means of at least one plunger. Such a method is known from the specification of published Dutch Patent Application No. 6 614 257.

With this known method, during the axially directed compression of the object, the liquid pressure within the object is maintained only at such'level, that the object is prevented from inflecting inwardly and a uniform radial expansion of the object is realised. Thereupon, the liquid pressure is increased for the expansion of the object against the die walls. The liquid pressure acting upon the object is obtained owing to an end portion of the plunger being arranged as a piston which is incorporated in a cylinder, so that a cylinder space is created which communicates with a pressure relief valve and, through a channel extending through the plunger tb the other end of this plunger, is in communication with the space within the object, no relative displacement between the object and the plunger being possible and the cylinder space, the channel and the space within the object being entirely filled with a liquid sO that, during the deformation of the object by a relative displacement of the piston in respect of the cylinder, the liquid pressure can first be maintained and afterwards increased with the possibility that the latter pressure is control- 3 led by the pressure relief valve.

It has appeared that, to realise a satisfactory deformation, the liquid pressure acting upon the object and the upsetting tension should be essentially kept constant during the entire deforming procedure.

According to the invention there is provided a method for cold deformation of a hollow metallic object by exerting anaxially directed compressive force on said object to deform the object against the walls of a die whilst a constant liquid pressure acts upon the internal surface of the object's wall to be deformed, the constant liquid pressure being generated by filling a space within the object bounded by at least the object's walls to be deformed to form an enclosed liquid mass, and by causing the free end of at least one plunger to be immersed within the liquid by means of a resilient force acting upon the plunger towards the object whereby the liquid pressure within the object is kept constant.

Preferably, during deforming the object, the object is shortened.

The resilient force acting upon the plunger may be obtained by loading a member acting as a spring to force the plunger into the liquid.

Conveniently during deforming the object, at least one substantially annular element is secured to the object.

Moreover, the invention provides an apparatus to carry out the method defined above, comprising upper and lower members to retain the object, means to move said retaining members relatively towards each other and away from each other, means to press the retaining members relatively towards each other, a die cooperating with the object to be deformed, means for filling with a liquid a space within the object bounded by at least the object's wall to be deformed, at least one plunger movably mounted relatively to the object, and means capable of exerting a resilient force upon the plunger towards the object to cause the free end of the plunger to be immersed within the liquid Whereby the liquid pressure within the object is kept constant.

Preferably the means for exerting a resilient force upon the plunger is a member acting as a spring.; Conveniently, a sleeve can be secured to the plunger near to the other end of the plunger, which sleeve has an internal collar forming a supporting surface for the spring, the other end of the spring bearing against a plate disposed at a distance from the upper end of the sleeve but which can be pressed against the upper side of the sleeve by the pressure means.

Preferably, around the sleeve is situated a second sleeve connected to said plate, the second sleeve having an internal collar which can cooperate with an external collar of the first sleeve to form a stop for the first sleeve in the direction towards the object. In this case, the plate to which the second sleeve is connected may be a table, a spring element being mounted between said table and a second table, the second table comprising one of the retaining members.

Conveniently, a retaining member may be mounted to retain one or more substantially fully or partly annular elements disposed around the object, which element or elements are fastened to the object during the deformation of the object.

By way of example, an apparatus for carrying out the method according to the invention will be described with reference to the accompanying drawings' in which :Fig 1 shows a longitudinal section of the apparatus in the situation shortly after the complete deformation of the object; 4-49 73 - 5 Fig. 2 shows the apparatus of Fig. 1 in the situation in which the plunger has been raised again after deformation of the object; and Fig. 3 shows the apparatus of Fig. 2 in the situation in which the deformed object can be removed, the object having an annular element secured around it, the figure also showing,in broken lines, the element as initially retained by a retaining member.

With reference to the drawings, an apparatus for the cold deformation of a hollow metallic object comprises a lower block 1 and an upper block 2 for engaging the object 3. In the block 2, a cavity 4 (Fig. 3) is formed, the wall of which forms part of the die against which the object is deformed, said cavity also serving to retain the upper end of the object 3. The lower block comprises the die portions 5 and 6 which are secured to the annular block portion 7, the die portion 6 being partly disposed in the interior of the ring of block portion 7, the lower end of which is sealed off by the plate 8. In the cavity of the annular block portion 7, a slide member 9 is situated, which is provided with a stem 10 extending through the die portion 6 and forming the lower retaining member for the object. A channel 11 extends through the slide member 9 and its stem 10 and is enlarged near the lower end of the slide member to form a non-return ball control valve 12, to which the channel 13 is connected which extends through the cover piece 14 and communicates with the supply conduit 15 which is passed through an aperture in ths annular block portion 7. The lower block 1 is secured to the lower table 16, through which an ejector pin 17 is mounted which passes further through an aperture in the plate 6 and engages the cover piece 14 of the slide member 9, while an ejector plate 18 is bearing against the bottom end of the pin so that, when the plate 18 is raised, the pin 17 will push upwardly the slide 9 and the object clamped on the stem 10, A'l® as shown in Eig. 3.

The guide rods 19 are fastened to the lower table 16, the upper ends of which are passed through the guide bushings 20 which are mounted in the intermediate table assembly 21. This table unit assembly 21 consists of two plates 22 and 23 fastened on top of each other. In the centre of the lower plate 22, an aperture is made which receives the upper block 2 while the upper plate 23 has an aperture to allow the plunger 24 to pass through it into the packing assembly 25.

Through the packing unit 25 and a passage formed in the block 2, the plunger 24 extends as far as the object 3, while a channel 26 extending through the plunger passes into a lateral outlet channel 28 through the non-return valve 27, the latter parts being mounted in the head 29 of the plunger. To this head 29, a threaded rod 30 is secured which is screwed into a bushing 31 retained by means of a lock nut 32. Through the threaded rod 30 and its extension, the rod portion 33, a passage 34 extends in which a pin may be inserted in order to keep the non-return valve 27 open.

The bushing 31 has an internal collar 35 and cup springs are provided between the collar 35 and a disc 37 in the upper table 41. Moreover, the bushing 31 is provided with an external collar 38 which can cooperate with an internal collar 39 of a second bushing 40 slidably arranged round the bushing 31, this second bushing being secured to the upper table 41. In this table 41, an aperture 42 is made, aligned with an aperture in the plate 37 for the passage of the said pin, while guide rods 43 are secured to the table, the lower ends of which extend through the guide bushings 44 mounted in the upper plate 23 of the intermediate assembly 21 and the apertures 45 formed in the lower plate 22 of the said assembly 21, stops 46 and 47 respec-7tively being formed at the rods 43. A spring 48 is mounted between the upper table 41 and the intermediate table unit 21.

Between the blocks 1 and 2, an annular retaining member 49 is disposed which is connected to the lower plate 22 of the assembly 21 by means of the centring pins 50, springs 51 being fitted round the pins 50. To this retaining member 49, an annular element 52 can be fastened which will be clamped around the object 3 when the latter is expanding, as shown in Fig. 3.

Deformation of an object by means of the apparatus as described above is carried out as follows.

In the beginning, the situation is as shown in Fig. 3, in which, of course, the deformed object 3 shown in this figure is not present, the usually cylindrical basic object to be deformed being placed upon the stem 10 of the slide 9 instead, and the annular element 52 indicated by broken lines in Fig. 3 being secured in the retaining member 49. The lower table 16 is then carried towards the intermediate table assembly 21 until the top end of the object is firmly clamped in the cavity 4 of the upper block 2 so that, a liquid proof seal is realised at the open ends of the object. Liquid is then introduced through the supply conduit 15 and the channels 13, 11 and 26 until this liquid emerges from the outlet channel 28, the non-return valve 27 being kept open by means of a pin inserted into the passage 34. After the liquid has emerged from the channel 28, the pin is removed as a result of which the non-return valve 27 will close. In this manner, it is guaranteed that the interior of the object to be deformed is entirely filled with liquid, the non-return valve 12 preventing this liquid from flowing back through the supply conduit 15. The upper table 41 is then forced towards the intermediate table assembly 21, as a result of which, through the spring 48, an axial compression force is exerted upon the object to be deformed. Also, through the cup springs 36, a force is then exerted upon the plunger so that a predetermined liquid pressure is obtained within the object the cup springs being allowed to be compressed. During the expansion of the object, the liquid volume within the object is kept constant owing to the plunger penetrating into the liquid, said plunger being biased by the cup springs so that sudden changes in volume nay also be absorbed, as a result of which the liquid pressure within the object may be kept constant. In this manner, the object is deformed as shown in Fig. 1. The upper table 41 is then raised in respect of the intermediate table assembly 21 as shown in Fig. 2, after which the lower table 16 is lowered as shown in Fig. 3, as a result of which the ejector pin 17 will push upwardly the slide 9, so that the deformed object 3 may be removed from the lower block 1. 4 9 7 3

Claims (11)

1. CLAIMSιΙ. Method for cold deformation of a hollow metallic object by exerting an axially directed compressive force on said object to deform the object against the wall of a die whilst a constant liquid pressure acts upon the internal surface of the object's wall to be deformed, the constant liquid pressure being generated by filling a space within the object bounded by at least the object's wall to be deformed to form an enclosed liquid mass, and by causing the free end of at least one plunger to be immersed within the liquid by means of a resilient force acting upon the plunger towards the object whereby the liquid pressure within the object is kept constant.

2. Method according to claim 1, wherein deforming the object, the object is shortened.

3. Method according to claim 1 or claim 2, wherein the resilient force acting upon the plunger is obtained by loading a member acting as a sprint to force the plunger into the liquid.

4. Method according to any one of the preceding claims, wherein, during deforming the object, at least one substantially annular element is secured to the object.

5. Apparatus to carry out a method according to any one of claims 1 to 4, comprising upper and lower members to retain the object, means to move said retaining members relatively towards each other and away from each other, means to press the retaining members relatively towards each other, a die cooperating with the object to be deformed, means for filling with a liquid a space within the object bounded by at least the object's wall to be deformed, at least one plunger movably mounted relatively to the object, and means capable of exerting a resilient force upon the plunger towards the object to cause the free end of the plunger to be immersed within the liquid whereby the liquid pressure within the object is kept constant. 44-97 3 10

6. Apparatus according to claim 5, wherein the means for exerting a resilient force upon the plunger is a member acting as a spring.

7. Apparatus according to claim 6, wherein a sleeve is secured to the plunger near the other end of the plunger, which sleeve has an internal collar forming a supporting surface for the spring, the other end of the spring bearing against a plate disposed at a distance from the upper end of the sleeve but which can be pressed against the upper side of the sleeve by the pressure means.

8. Apparatus according to claim 7, wherein around the sleeve is situated a second sleeve connected to said plate, the second sleeve having an internal collar which can cooperate with an external collar of the first sleeve to forii a stop for the first sleeve in the direction towards the object.

9. Apparatus according to claim 8, wherein the plate to which the second sleeve is connected in a table, a spring element being mounted between said table and a second table, the second table comprising one of the retaining members.

10.. Apparatus according to any one of claims 5 to 9, wherein a retaining member is mounted to retain one or more substantially fully or partly annular elements disposed around the object, which elements are fastened to the object during the deformation of thaobject. 11. Method for the cold forming of hollow metal bodies substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 12. Apparatus for forming hollow metal bodies substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 44s

11. - 11 13. Hollow bodies formed by a method or apparatus as claimed in any one of the preceding claims. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS. COLDEF B.V.