US3709014A

US3709014A - Press for hydrostatic extrusion

Info

Publication number: US3709014A
Application number: US00138201A
Authority: US
Inventors: T Landa; P Syvakari; E Westman
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1970-04-30
Filing date: 1971-04-28
Publication date: 1973-01-09
Anticipated expiration: 1990-01-09
Also published as: DE2120825A1; DE2120825B2; CA923076A; BE761088A; SU377994A3; AT308495B; SE338550B; GB1306321A; IE35172B1; NO132340B; NO132340C; FR2090993A5; DE2120825C3; DK128271B; NL7105805A; IE35172L; CH526348A

Abstract

A press for hydrostatic extrusion includes a press stand and a high pressure cylinder displaceable in the stand. A punch is mounted for movement into the high pressure cylinder to produce the extrusion pressure therein. The billet and die are positioned by a manipulating arrangement between the open end of the high pressure cylinder and a die support, and the cylinder is moved over the billet and die. Pressure fluid is then introduced through the die support and die into the pressure chamber, flow of the fluid out of the chamber being prevented by a valve arrangement or by seating of the billet against the die. The punch is then advanced into the pressure cylinder to produce extrusion.

Description

O Umted States Patent [1 1 [111 3,709,014

Landa et al. 14 1 Jan. 9, 1973 54 PRESS FOR HYDROSTATIC 2,558,035 6/1951 Bridgman ..72/60 EXTRUSION 3,440,849 4/1969 Hardy et al ..72/6O 3,1 3 l9 [75] Inventors: Torstein Landa; Pertti Syvakari; 26 096 I 64 Gerard eta] 72/60 Erikd wesunan an of vasteras' Primary Examiner-Richard J. Herbst Swe en Attorney-Jennings Bailey, Jr. [73] Assignee: Allmanna Svenska Elektrlska Aktiebolaget, Vasteras, Sweden ABSTRACT [22] Filed: April 28, 1971 A press for hydrostatic extrusion includes a press stand and a high pressure cylinder displaceable in the [2]] Appl 138301 stand. A punch is mounted for movement into the high pressure cylinder to produce the extrusion pres- [30] Foreign Application Priority Data sure therein. The billet and die are positioned by a manipulating arrangement between the open end of Apr1l30,1970 Sweden ..60l0/70 the high pressure cylinder and a die support, and the cylinder is moved over the billet and die. Pressure ill fluid is then introduced through the die Support and [58] c 72/60 die into the pressure chamber, flow of the fluid out of a the chamber being prevented y a valve arrangement or by seating of the billet against the die. The punch is [56] References Cited then advanced into the pressure cylinder to produce UNITED STATES PATENTS extruslon- 3,531,965 10/1970 Nilsson ..72/60 6 Claims, 18 Drawing Figures 5.9 56 97 43! I2 fl PATENTEDJAN 91975 3,709,014

SHEET F 7 Fig. 2

Fig 3 PATENTEUJAM 9 ms 3.709.014

SHEET 6 OF 7 Fig. /4

Fig. /5

INVENTORS "@RSFEIN LANDF B PERTH SWAKAR ERH w EST/MA" PRESS FOR HYDROSTATIC EXTRUSION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press, preferably a horizontal press, for hydrostatic extrusion of a billet enclosed in a high pressure chamber.

2. The Prior Art Presses for hydrostatic extrusion normally have a horizontal high pressure cylinder which is displaceable in a press stand and which, together with a die with an opening, which can project into the cylinder, and a pressure-generating punch insertable into the cylinder, forms a closed chamber. A billet to be extruded is placed in the pressure chamber, after which the chamber is filled with a pressure medium. The insertion of the pressure-generating punch into the pressure chamber generates a pressure in the pressure medium which acts uniformly from all sides on the billet and tends to press it out through the die' opening so that a rod is formed with the cross-section of the die opening. The pressure required for the extrusion depends partly on the material of the billet and partly on the area reduction ratio, by which is meant the ratio between the cross-section of the billet used and the cross-section of the product. The area reduction ratio which can be achieved increases sharply with increased pressure, but the strength of the pressure chamber limits this pressure. NOwadays it is possible to operate in the range of kbar during regular production.

It is desirable to completely fill the pressure chamber with a liquid pressure medium in order to be able to aChieve extrusion pressure with the least possible displacement of the pressure-generating punch. If the pressure chamber is not completely filled it means that there is a certain volume of gas therein when the pressure-generating punch is being pushed in. Since the gas is more compressible than a liquid, the compression of the gas causes a relatively large and undersired displacement of the pressure-generating punch. The volume of the gas causes the useful volume of the pressure chamber to decrease. The amount of billet which can be extruded is decreased to the same extent.

One method of filling a pressure chamber is shown in US. Pat. No. 3,531,965 in which the pressure cylinder is provided on the punch side with a chamber for the supply of liquid while the cylinder is being pushed in over the die so that the pressure chamber is closed. During each operating cycle the pressure-generating punch must be drawn out of the high pressure seal which forms the seal between the cylinder and the pressure-generating punch. Seals for extremely high pressure which seal between two parts movable in relation to each other are extremely sensitive to damage and such damage normally occurs when the punch is inserted through the seal.

SUMMARY OF THE INVENTION The invention provides a press for hydrostatic extrusion including a press stand and a high pressure cylinder displaceable in the stand. A punch is mounted for movement into the high pressure cylinder to produce the extrusion pressure therein. The billet and die are positioned by a manipulating arrangement between the open end of the high pressure cylinder and a die support, and the cylinder is moved over the billet and die. Pressure fluid is then introduced through the die support into the pressure chamber, flow of the fluid out of the chamber being prevented by a valve arrangement or by seating of the billet against the die. The punch is then advanced into the pressure cylinder to produce extrusion.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further described with reference to the accompanying drawings.

FIGS. 1 8 show a complete operating cycle in a press according to the invention.

FIG. 9 is a view from above showing operating cylinders for moving the high pressure cylinder of the pressure chamber. (The manipulator device of FIG. 10 is omitted).

FIG. 10 is a section on the line AA of FIG. 1 showing a side view of a manipulator device for inserting a billet and a die.

FIG. 11 shows on a larger scale the right end of the high pressure cylinder with an inserted billet and die and an injecting device inserted'in the die support.

FIGS. 12-15 show four positions of an operating cycle in a press designed to be loaded through the press yoke.

FIG. 16 shows on a larger scale the right end of a press of FIGS. 12-15 with a billet, a die and die support inserted in the high pressure cylinder and an injecting device inserted in the die support.

FIG. 17 is a section on the line B-B of FIG. 12, showing the movable pressure distributing plates for taking up die forces.

FIG. 18 shows on a larger scale the billet holder used and the surrounding parts of the high pressure cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, 1 designates a horizontal press stand. A horizontal high-pressure cylinder 2 is axially displaceable in this stand. As shown in FIG. 9, the high pressure cylinder 2 is displaced by two hydraulic cylin-' ders 50, attached to the press stand 1 by brackets 51. The piston rods 52 are connected to brackets 53, which are attached to the cylinder 2. The cylinders are connected to a pressure medium source (not shown) by

conduits

54 and 55. On the left end of the press stand there is an operating cylinder 3 with a piston 4 shaped as a differential piston and connected to a pressuregenerating punch 5 which penetrates into the highpressure cylinder 2 and generates the pressure necessary for the extrusion in the pressure chamber 30 which is formed by the cylinder 2, punch 5 and a die 6 projecting into the opposite opening of the cylinder. The

spaces

7 and 8 on either side of the piston communicate through a bore 9 and a conduit 56 passing through a hole 57 in the press yoke and a bore 10 and a conduit 58 passing through a hole 59 in the press stand 1 with operating valves (not shown) and with a pressure medium source. In the high pressure cylinder 2 is a sleeve 11 and

seals

12 and 13 which seal between the cylinder 2 and the punch 5 and the die supports 14 or 15, respectively. During a normal operating cycle the punch 5 is never drawn out of the seal 12, something which considerably contributes to increasing the length of life of this seal 12 which is extremely sensitive to damage because of the movement between the punch and the seal under high pressure. In the sleeve 11 a billet-holder 16 is axially movable. This holder 16 is shown in a larger scale in FIG. 18. his provided with a projecting guide bar 18 which runs in a slit 19. The movement is limited by

stop surfaces

20 and 21 at the ends of the slit. The billet-holder also includes a spring member 22 which-presses the billet 23 against the die 12 before compression is initiated. The holder has a bore 60 and in one end a seat 61 for the spring 22. In this seat there is an opening 62 allowing pressure medium to pass through the holder. The end facing the billet is formed as a funnel with sloping sides 63 for guiding the billet 23 into the bore 60.

The press according to FIGS. 1 9 has a die support 15 which is made in one piece with the pressure-distirbuting plate 24 which transmits pressure to one yoke 25 of the press stand. The pressure cylinder can be moved so far to the left that a billet 23 and a die 6 can be inserted from the side between the cylinder 2 and the die support 15 by means ofa manipulator 65 so that billet and die come opposite the opening of the cylinder 2. In FIGS. 1 and 8 only gripping

members

26 and 27 of the manipulator 65 are shown. The manipulator 65 comprises, as shown in FIG. 10, a lever 66, pivoted on shaft 67, carried in a bracket 68,'attached to the press stand 1. Only the gripping member 27 for holding the die 6 can. beseen in FIG. 10. The gripping members consist of a lower lower part 27a, fixedly attached to the lever 66, and an upper part 27b pivoted between two brackets 69 on the lever 66 and provided with a lever 70.. An operating rod 71 of an operating cylinder 72 is connected to the lever 70. The cylinder 72 is pivoted between the two brackets 75 on the lever 66, and connected to control valves and a pressure medium source (not shown) by

conduits

74 and 75. An operating rod 76 f an operating cylinder 77 is pivoted in the upper end of the lever 66. The cylinder 77 is also pivoted in the bracket 68. By means of

conduits

78 and 79, it is connected to control valves (not shown) and a pressure medium source. a

In the following a complete operating cycle will be described. Atthe start of an operating cycle the highpressure cylinder has been pushed as farm the left as possible as shown in FIG. lpA billet'23and a die 6 are placed by the manipulator 65 opposite to the opening of the cylinder 2, after which the billet and the die are moved towards the die support and the cylinder is moved to the right over the billet until spring 22 of the billet holder 16 comes into contact with the billet 23. The billet holder may be provided with friction elements so that it does not run easily in the cylinder and a force is thus obtained which presses the billet 23 and the die towards the die support 15 during the latter part of the displacement of the cylinder 2 when the manipulator fingers26'and 27 must be removed so as not to prevent the movement of the cylinder completely in over the billet and the die so that the pressure chamber 30 is entirely closed (see FIG. 2). At this stage oil may be injected in the gap between the billet 23 and the opening in the cylinder 2 so that the chamber is substantially filled with pressure medium. Upon further movement of the. cylinder 2 to the right the pressure medium space between the billet and the cylinder in the pressure chamber 30 is decreased, whereupon mostly air is forced out during continued closing of the pressure chamber. When the pressure chamber is completely closed, the billet holder 16 is in its lefthand limit position which is determined by the stop surface in the slit 19 of the sleeve 1 1, in which slit the guide bar l8joined to the billet holder runs. The length of the billet is such that the spring member 22 is compressed during the latter part of the movement of the cylinder 2 so that a desired pressure is obtained against the billet 23 so that this and the die are pressure with the desired force against the die support 15. The pressure generating punch is moved at the same time to the right so that it is not withdrawn from the seal 12 (see FIG. 3). As

shown ,in FIGS. 4 and 11, an injection tube 31 with a seal 32 is inserted into the pressure-distributing plate 24 joined to the die support 15 and pressure medium from a source, not shown in the drawings, is supplied at a high pressure to the pressure chamber 30; By high pressure is meant a pressure of-at least 25 bar, but usually the pressure is considerably higher, preferably betweenlOO and 500 bar. Any air remaining in the pressure chamber 30 is compressed so that its volume is so negligible that this quantity of air can. be accepted in the pressure chamber since it only negligibly affects the movement of the pressure-generating punch 5 when the pressure-generating punch 5 when the pressure is increased to extrusion level. When the pressure medium is supplied, either the die is lifted from the die support as shown in FIG. 11 and pressure. medium passes between the die and the die supportand through opening 33 out into the pressure chamber 30, or the billet 23 is lifted from the die 6 as shown in FIG. 16. When'the injection tube 31 is removed, the die 6 and die holder 15 or the billet 5 and die 6 form valve members in a valve which prevents pressure mediumfrom flowing out of the pressure chamber 30. The pressure chamber 30 is now almost entirely. filed with pressure medium. The position is shown in FIG. 5. Pressure medium is now supplied tothe space 7 in the operating cylinder 3 so that the pressure-generating punch 5 is pressed with great force into the cylinder 2 and generates the pressure necessary for extrusion in the chamber 30. FIG. 6 shows the position in the middle of the extrusion process itself. In the position shown in FIG. 7,-the extrusion is interrupted and the cylinder 2 is returned with the operating punch 4 and punch 5 to its lefthand limit position as shown in FIG. 8; The die '6 with the remainder of the billet 35 is then removed form the support 15 and a cutting machine 33 cuts the extruded product 34 between the die 6 and die support 15. A new operating cycle can then be started.

FIGS. 12 to 16 show a press according to the invention in which the billet is inserted into the cylinder through the opening 40 in one yoke 25 of the press stand 1. The opening 40 must then be of such a size that a manipulator, not shown, can be inserted through it with the billet 23, die 6 and die support 14. The pressure against the die support 14 is transmitted to yoke 25 by a divided pressure-distributing plate 41 consisting of two equal parts 41a and 41b which can be operated between a closed and an open position. FIG. 17 shows the arrangement of the plate parts. The parts 41a and 41b are guided by two guide members 80 and connected to the

piston rods

81 and 82 of the operating

cylinders

83 and 84 attached to the press stand 1.'The

cylinders are connected to control valves and a pressure medium source (not shown) by

conduits

85, 86, 87 and 88. The plate members 41a and 41b can be moved by means of the

cylinders

83 and 84 between the force absorbing position shown in FIGS. l4, l6 and 17 and a withdrawn position shown in FIGS. l2, l3 and in which position a billet can be loaded through the opening formed between the plate members by means of manipulator means. Before the manipulator is withdrawn, a tubular rod 42 is inserted in the die support 14 to inject pressure medium into the now closed pressure chamber. This has a shoulder 43 so that it can keep the die support pressed into the cylinder opening while the two parts 410 and 41b of the pressure-distributing plate 41 are brought together. Pressure medium is then injected into the pressure chamber (see FIGS. 13 and 14). After the extrusion the support parts 41a and 41b are pulled apart and the die support 14 and the die 16 with the remainder of the billet 35 are withdrawn through the opening 40 in the yoke 25 of the press stand (see FIG. 15). A cutting machine 33 then cuts the extruded product 34 near the die 6 and the remainder of the billet 35 is removed from the die, after which this can be used again. In this embodiment, the cutting takes place completely outside the press itself, which decreases the risk of metal chips coming between the various parts of the press causing trouble during operation. The extrusion cycle is otherwise similar to that previously described.

Of course the invention is not limited to the embodiments shown. Many variations are feasible within the scope of the following claims.

We claim:

1. Press for hydrostatic extrusion comprising a press stand, a pressure chamber which is formed by a high pressure cylinder open at one end displaceable in the press stand, a die support at one end of the press stand, a die insertable between the open end of the cylinder and the die support and having an opening to shape a product, a punch projecting into the other end of the cylinder to generate a pressure in apressure medium enclosed in the pressure chamber necessary for extrusion of a billet, means for operating the pressuregenerating punch and the high pressure cylinder, a mechanism for positioning a billet and the die between the open end of the high pressure cylinder and the die support, and a billet holder in the cylinder to hold the billet against the die before the extrusion process, in

which the press is provided with insertable and removable means for injecting pressure medium into the pressure chamber through the die support for filling the pressure chamber and placing it under pressure before increasing the pressure to extrusion level by inserting the pressure-generating punch, and with means to prevent pressure medium from escaping from the pressure chamber while the injection means is being removed.

2. Press according to claim 1, in which the means to prevent escape of pressure medium includes a surface on the die engageable with the front part of the billet to form a valve means sealing against the seat.

3. Press according to claim 1, in which the means to prevent escape of pressure medium includes a valve means in which the die support forms the valve seat and the die is movable with respect to the die support and seals against the seat.

4. Press according to claim 1, which includes a billet holder which is axially movable in the high pressure cylinder and which centers the billet at its inner end and a spring engaging the billet holder to press the billet against the die.

5. Press according to claim 1, in which a high pressure seal is provided between the high pressure cylinder and the punch unit, the means for operating the high pressure cylinder and the punch includes means to keep the punch always inserted so far into the high pressure cylinder that its front end is always inside the high pressure seal between the punch and the cylinder.

6. A method of operating a press for hydrostatic extrusion which comprises a press stand, a pressure chamber which is formed by a high pressure cylinder open at one end displaceable in the press stand, a die support at one end of the press stand, and a punch projecting into the cylinder to generate a pressure in a pressure medium enclosed in the pressure chamber necessary for extrusion of a billet, which method comprises inserting a billet and a die between the open end of the high pressure cylinder and the die support, advancing the high pressure cylinder over the billet and the die, injecting pressure medium into the pressure chamber through the die support for filling the pressure chamber and placing it under pressure while preventing pressure medium from escaping from the pressure chamber and increasing the pressure to extrusion level by advancing the pressure-generating punch.

Claims

1. Press for hydrostatic extrusion comprising a press stand, a pressure chamber which is formed by a high pressure cylinder open at one end displaceable in the press stand, a die support at one end of the press stand, a die insertable between the open end of the cylinder and the die support and having an opening to shape a product, a punch projecting into the other end of the cylinder to generate a pressure in a pressure medium enclosed in the pressure chamber necessary for extrusion of a billet, means for operating the pressure-generating punch and the high pressure cylinder, a mechanism for positioning a billet and the die between the open end of the high pressure cylinder and the die support, and a billet holder in the cylinder to hold the billet against the die before the extrusion process, in which the press is provided with insertable and removable means for injecting pressure medium into the pressure chamber through the die support for filling the pressure chamber and placing it under pressure before increasing the pressure to extrusion level by inserting the pressuregenerating punch, and with means to prevent pressure medium from escaping from the pressure chamber while the injection means is being removed.