US1980333A

US1980333A - Pressure die-casting machine with device for uniformly controlling the movable partsby means of gaseous and hydraulic pressure media

Info

Publication number: US1980333A
Application number: US577727A
Authority: US
Inventors: Haessler Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-11-27
Filing date: 1931-11-27
Publication date: 1934-11-13
Anticipated expiration: 1951-11-13

Description

Nov. 13, 1934. P. HAESSLER 1,980,333 PRESSURE DIE CASTING MACHINE WITH DEVICE FOR UNIFORMLY CONTROLLING THE MOVABLE PARTS BY IEANS OF GASEOUS AND HYDRAULIC PRESSURE MEDIA Filed Nov. 27, 1931 4 Sheets-Sheet. l

Nov. 13, 1934. 1P. HAESSLER 8 PRESSURE DIE CASTING-MACHINE WITH DEVICE FOR UNIFORMLY CONTROLLING THE MOVABLE PARTS BY MEANS OF GASEOUS AND HYDRAULIC PRESSURE MEDIA Filed Nov. 27,- 1931 4 Sheets- Sheet 2 Nov, 13, 1934. p ss 1,980,333 PRESSURE DIE CASTING MACHINE WITH DEVICE FOR UNIFORMLY CONTROLLING THE MOVABLE PARTS BY MEANS OF cmsmous AND HYDRAULIC PRESSURE MEDIA Filed Nov. 27. .1931 4 Sheets-Sheet 5 Fig. 8

Nov; 13, 1934. P. HAESSLER 1,930,333 PRESSURE DIE CASTING MACHINE WITH DEVICE FOR UNIFORMLY CONTROLLING THE MOVABLE PARTS BY MEANS OF GASEQUS AND HYDRAULIC PRESSURE MEDIA Filed Nov. 27, 1951 4 Sheets-Sheet 4 Fig. 9

A l B 7 106 I07 14 Fig. 15

Fig. 13

Fig.11 1 121 ii 4-14 3 E m 171:

Patented Nov. 13, 1934 UNITED STATES PRESSURE DIE-CASTING MACHINE WITH DEVICE FOR UNIFORMLY CONTROLLING THE MOVABLE PARTS BY MEANS OF GASEOUS AND HYDRAULIC PRESSURE 7 MEDIA Paul Haessler, Nuremberg, Germany Application November 27, 1931, Serial No. 577,727

4 Claims. (01. 22-92) This invention relates to improvements on pressure dieor pressure casting machine with device for uniformly controlling the movable parts by means of gaseous and hydraulic pressure media. The machine serves chiefly for working metals and metal alloys having a high melting point. However metals having a lower melting point, such as white metals, lead, tin, zinc, aluminium and their alloys can be worked on the machine, without it being necessary to effect any considerable alterations in the die or in the construction of the machine.

In designing the machine the leading idea was to construct same so that it works economically not only for manufacturing in large quantities, but also for the manufacture of relatively small quantities of castings.

This condition could however only be fulfilled, when the function and construction of the machine rendered possible the employment of simply constructed dies, so that their cost, distributed over the quantity to be manufactured, does not too greatly influence the price of the individual casting.

Experience has shown, however, that the devices mounted on the die and serving for effecting the movement of the cores, the ejection bolts and other moved die parts render the construction of the die more diificult and more expensive.

In order to make these parts as simple as possible, up to four cylinders, controlled by liquid pressure medium, are arranged on the machine at the height of the casting die, said cylinders being interconnected and communicate with the control elements through rigid pipe conduits and are adjustable and can be employed for any kind of die. The operative elements of the die parts are so constructed that the die parts to be moved are merely suspended therein, so that they can be quickly exchanged. The operation of the machine is such, that the material to be worked is charged in liquid or plastic condition into the pressure cylinder bore of the bottom part of the die and, after the two die halves have been brought together, is forced into the die by means of a pressing piston, actuated by a liquid or gaseous pressure medium.

Control valves particularly adapted to the purpose of use are provided for the proper distribution of the liquid or gaseous pressure medium to the working cylinders of the machine. The valves are highly stressed by the rapid succession of controlling operations. Their operation must be possible without the consumption of considerable force, so that the operator attending the machine is not prematurely tired.

The valves must further be so constructed that any desired speed can be easily obtained for the machine parts to be moved.

A series of improvements and novelties on the machine and also on the control elementswhich correspond particularly to the conditions of the pressure die-casting work will be hereinafter described.

Several embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:

Fig. 1 shows in side elevation the machine with part section through the extrusion cylinder and 4% through the cylinder influencing the draw cores for the die. a

Fig. 2 is a top plan view of the lower part of the machine showing the control valves with connecting pipe conduits between same and the cylinders for the draw cores.

Fig. 3 shows in top plan view one of the plates connecting each two ejection rods and liked by screwing on the abutment plate.

Fig. 4 is a top plan view of the plate in which the movable die parts for the cores are to be suspended.

Fig. 5 shows in elevation the air control element with arrangement for horizontally shifting same.

Fig. 6 shows the air control element in vertical section. I

Fig. 6a is a bottom plan view of the auxiliary valve of the air control element.

Fig. 7 shows the air control element in front elevation;

Fig. 8 is a'vertical section through the pressure water control element taken on line VIII- VIII of Figs. 2 and 11.

Fig. 9 is a vertical section through the circulating valve of the pressure valve control element taken on line IXIX of Figs. 2 and 11 and further illustrating by dot and dash lines, the

elements

113, 11311 and 133 for a clearer understanding of the operation.

Fig. 10 is a top plan view showing the two cam shafts with hand wheels arranged above the 7 pressure water control valve.

Fig. 11 shows the valve block in top plan view with the bores for the valve seats.

Figs. 12 to 15 are diagrammatic views showing the cams, the balance beam and the circulating valve in different controlling positions.

Fig. 16 is a part end view seen in the direction Qt the arrow XVI of Fig. 2.

Fig. 17 is a part section on line XVII-XVII of Fig. 1 showing the machine in course of conversion with the bolts 4e. and 4b, and the sleeve 38 removed for purposes of clarity.

The machine is erected on a base 1 carrying a table plate 2. Four upwardlyextending columns 30 to 3d and two downwardly extending

traverses

4a and 4b are mounted on the table 2. The columns 3a to 3d serve as support for the cross head 5 and pressure plate'6. These columns are screw threaded at their upper ends. The cross head can be displaced and adjusted in vertical direction with the aid of nuts 7 and 8 on the screw threaded portions of the columns.

A closing cylinder 9 closed by a cover 10 is mounted in a bore in the cross head 5. A closing piston 11 is shiftable in the cylinder 9. A piston rod 12 is packed towards the outer side in the cylinder cover 10 "by means of a stufling box 13. The piston rod 12 carries the pressure plate 6 on its lower end. The pressure water feed and discharge to and from the cylinder 9 is efiected through

pipe conduits

14 and 15 respectively, which are connected to the upper and lower ends of the cylinder by means of

flanges

16 and 17. Two brackets 18, to which the upper part 19 of the die is fixed by screws, are mounted on the pressure plate 6. T-grooves 21 are provided in the table 2 for fixing the lower part of the die.

An ejection plate 22 moves between the tw blocks 18, ejection bolts 23 guided in the upper part19 of the die being screwed in this ejection plate 22. The ejection plate 22 is carried by four screw threaded rods 24a to 24d, extending through an abutment plate 25 made in one piece with the cross head 5. In order to facilitate the removal of the rods, the apertures in the abutment plate 25 are in the form of open slots 26. Two plates 27 serve for guiding each two of the rods which extend through bores in the plates. The plates 27 are attached to the abutment plate 25 by means of bolts 27a (Fig. 3).

The. rods 24a to 24d carry

abutment nuts

28 and 29 above and below the abutment plate 25 respectively. These nuts are so adjustable that, after the closing of the die parts 19 and 20, the ejection bolts 23 are pulled back and, after the opening of the die, they are pushed forward. For the purpose of removing the rods 24a to 24d, the nuts on the lower end thereof and the fixing bolts 27a for the guide plate 27 are unscrewed, whereupon the two rods held by one of the plates 27 can be removed from the slots 26, which are open at one end, without it being necessary to displace the

abutment nuts

28 and 29.

' When refitting the rods a readjustment of the abutment nuts '28, 29 is not necessary, when these have once been adjusted. V

The two

traverses

4a, 4b mounted on the table 2 carry the pressure cylinder 30, closed at the top by a. cover 31. A piston rod 32 is packed towards the outer'side by the stufling box 310. of the cylinder 30. The pressure piston 34 is fixed to the piston rod 32 by means of a screw bolt 35 with distance rings 36 interposed thereon. The pressure piston 34 is guided in a sleeve 37, which is inserted from above into a bore in the table 2. The sleeve 37 extends into a corresponding bore in the cylinder cover 31. Thus, the cylinder 30 is suspended absolutely concentrically below the sleeve 37 and jamming of the pressure piston 34 in the relatively long sleeve 37 cannot possibly and the cylinder 30 is regulated by distance sleeves 38.

The pressure medium is fed to the upper and I or advisable to arrange the pressure cylinder bore in the middle of the die plate 20, provision is made for accommodating same eccentrically to the die.

For this purpose further bores for accommodating the

traverses

4a and 4b and the sleeve 37 are provided in the table 2 and arranged in the direction towards the rear edge of the table plate 2. The entire cylinder aggregate may also be built in the additional bores of the table plate. In order to be able to efiect this displacement, two lugs are provided on the cylinder and holes 46 registering therewith in the base 1.

Two rods are inserted in these holes when fitting, so that the cylinder 30, after loosening the nuts 47 of the

traverses

4a, 4b, rests with its lugs 45 on these rods. The traverses 4a and 4b and the sleeve 37 are then pulled out at the top, the cylinder 30 shifted to under the lateral bores, the traverses and sleeves again inserted and the whole screwed together with the aid of the nuts In order to be able to work in spite of the adjustability of the closing cylinder 9 and working cylinder 30 with the rigid pipe connections between same and the

control elements

48 and 70, these control elements are shiftably mounted on plates 50 and brackets 51 respectively provided with horizontally and vertically extended slots 52 and-53 for the fixation bolts, so that the

control elements

48 and 70 can participate on the shifting of the cylinders, cylinder 9 in vertical direction and cylinder 30 in horizontal and vertical direction, without removing of the pipe connections.

Angle pieces 54 are slipped over the four columns 3a to 3d of the machine, the heads 55 of these angle pieces serving as supports for the cylinders 57 which are each provided with a flange plate 56 and made in one piece therewith.

These heads have vertical grooves 58 and the flange plates 56 have horizontal grooves 59, in which the screw bolts 60 are accommodated (Fig. 2). The angle pieces 54 are adjustable in height and clamped on the columns 3a to 3d with the aid of screws 61 (Fig. 2). The vertical and-horizontal grooves in the heads 55 of the angle pieces 54 and in the plate 56 allow the vertical and horizontal adjusting of: the cylinder 57. By inserting suitable wedge plates 62 (Fig. 2), the cylinder 57 can be brought into and clamped in any inclined position.-

A piston 63 acts through the intermediary of its piston rod 64 on a transverse plate 65 screwed thereon. Through internally threaded lateral bores of plate 65 two rods 66 extend which further extend through the flange plate 56 and are guided therein in brass bushes 67. The rods 66 have on their end heads68 in which an annular groove is cut. The plate 69 is suspended in this 7 1 groove so that it can be exchanged with the cores fixed thereon without loss of time.

7 The stroke of the plate 69 is limited towards the front by the lower part 20 of the die, and the amplitude of the stroke can be determined by shifting the transverse plate 65 along the rods 66.

The pressure medium is fed from the control element 48 to the cylinder 57 through pipe conduits or hoses 130 and 131 (Fig. 2). By selecting suitable cross-sectional areas for these conduits, the movement of the pistons in the cylinders can be adjusted successively in any desired sequence.

. For controlling the working piston 33, liquid or gaseous pressure media may be employed. When employing gaseous pressure medium, it has been found that, during the returning of the piston 33 into its initial position, the working piston,

rigidly connected to the pressure piston 34, often strikes heavily against the bottom of the working cylinder 30, even in the case of careful operation, especially, when the pressure piston 34 jams in the bore 44 of the lower part 20 of the die. This may lead to damage to the machine, such as piston rod fractures, cracking of cylinders and similar damage.

Figs. 6 and '7 show a control element, suitable for controlling the working piston 33 by means of gaseous pressure medium, this element be'ngprovided with an arrangement, which automatically prevents the working piston 33 from striking against the bottom of the cylinder 30, without any external influence whatever.

This is effected in that the valve piston communicating with the lower piston space in the working cylinder 30 is provided with an axial bore and an auxiliary valve is mounted therein in such a manner that this auxiliary valve can completely or partially close during the downward stroke of the working piston 33, so that an ar cushion braking the return movement of the working piston is formed in the lower cylinder space, in the pipe conduit communicating therewith and in the corresponding valve space.

This control element consists of a. valve block '70 having bores 71a and 71b and above and below same bores 72a, 72b, '72c and 7211. The bores 72a and 72b serve as seats for

housings

73a, 73b provided with flanges. The

bores

74a and 74b in the

housings

73a and 73b communicate with an exhaust port '75, and the bores 72c and 7211 with a compressed air feed conduit '76 through a transverse bore '77. A transverse bore '78 extends from the bore 71a and communicates with the lower part of the working cylinder 30 through the pipe 39. The upper part of the cylinder 30 is connected to bores '79 and 71b of the rght hand valve 94 by means of the pipe conduit 40. The T- shaped lever serves with its

arms

81 and 82 for controlling the two valves mounted in the bores of the valve body '70.

The set of valves mounted in the

bores

71a, 72a and 720 consists of a valve cone 83 with subsidiary valve 84, both of which are pressed on to their seats by means of a spiral spring 85, of a valve piston 86, having an axial bore serving as guide for a spring-loaded valve cone 8'7 and for a valve cone 88, and of a pressure bolt 89. The valve piston 86 moves in cup packing 90, which packs the space 71a relative to the

spaces

72a and 74a. Bores 91 and the axial bore 86a or the valve piston 86 connect the space 71a with the

spaces

72a and 74a.

The valves of the set of valves in the bores 71b, 72b and 74b consist each of a valve cone 92 with pre-valve 93, which are spring-loaded and of the pressure bolt 89. A hollow valve piston 94, in the axial bore of which a valve cone 95 is guided sl'des in a cup packing 96, which packs the space 71b relative to the spaces'72b and 74b. Bores 9'7 and the axial bore 94min the valve piston 94 connect these spaces the one with the other.

The operation of the control element is as follows: If the lever 80 is pulled in the direction of the arrow 99, the left hand valve becomes operative. The arm 81 presses on the pressure bolt 89; the valve cone 88 comes to sit on its seat turned in the end face of the valve piston 86 whereby the auxiliary valve 87, which is already open, is further opened. In the further course of the downward movement the piston 86 is carried along, it first opens the auxiliary valve 84'and then the main valve 83. The compressed air passes from the bores '76 and '77 through the open valve and the pipe conduit 39 extending from the bore '78 into the lower portion of the working cylinder 30. The working piston 33 and the pressure piston 34 rigidly connected thereto move upwards, the pressure piston forcing the material to be pressed into the space of the closed die 19,

The air in the upper part of the working cylinder 30 escapes through the connecting conduit 40 between this part of the cylinder and the bore '79, through bore9'7 and the axial bore in the valve piston 94, in pressing upwards the valve 95, through the space 74b and the exhaust port '75 into the atmosphere.

After termination of the pressure casting, that is, after the equilibration of pressure in the compressed air supply conduit, the lever 80 is returned into its intermediate position, in which it is secured by a spring bolt 98a engaging in a notch 98.

The valves 83 and 84 close under the action of the spiral spring 85, the valve piston 86 and v necting pipe conduit 39, the bores '78 and 91 through the axial bore 86a in the valve piston 86 and through the space 74a into the compressed air discharge conduit '75.

The lever ,80 is thrown over in the direction of the arrow 100 for pulling back the pressing piston movement and in turn opens first the pre-valve 93 and subsequently the main valve 92. The compressed air flows through the bores '76 and '77, the open valves 92 and 93, the space 717), the bore '79 and the pipe conduit 40 extending therefrom into the upper portion of the working cylnder 30. The working piston 33 and the pressure piston 34, rigidly connected therewith, move in downward direction.

Owing to the movement of the lever 80 in the direction of the arrow 100 the arm 81 has been lifted off the left hand pressure bolt 89. The spiral pressure spring mounted under the valve cone 8'7 has closed the valve 87, overcoming the weight of the

parts

87, 88 and 89. As this valve is not intended to entirely prevent the escape- .ment of the air, but only to strongly throttle same,

notches 8771 are cut in the valve seat (Fig. 6a). These notches enable a slow escapement of the air from the lower part of the working cylinder 30 through the pipe conduit 31 extending from the bore 78, the bore 78 itself, then through the bore 91, the axial bore 86a in the valve piston 86 and through the space 74a into the exhaust port 75. The strongly throttled air forms under the descending working piston a buffer, which prevents the piston from striking heavily against the bottom of the working cylinder.

When the lever is being brought back into its intermediate position the valves 92 and 93 close. The arm 81 again bears on the left hand pressure bolt 89, shifts the valve cone 88 in downward direction and thus opens the valve 87. The air enclosed below the working piston can flow off into the exhaust port 75. The compressed air remaining in the upper portion of the pressure piston has in the meantime lifted the valve cone 95 and thus established communication with the space 74b and the exhaust port 75.

When a liquid pressure medium is employed either pumps alone or also accumulator service, that is liquid containers, or pressure water storage tanks, may be used.

In the case of only pumps being used a. device must be provided in the control element for returning the pressure water lifted by the pump directly to the water tank, when the pump is in position of rest, so that, when the valves are in this position, working of the pump on pressure does not occur in order to economize power and t save the pump.

A control element will be hereinafter described which is illustrated in Figs. 8 to 15 and which is adapted to the above mentioned conditions.

The drawings show a valve built solely for pump service and for controlling two groups of cylinders A and B (for example closing cylinder 9 and cylinder 57 for extracting the cores). The valve consists of four sets of control valves and of one set of circulating valves. For service with a pressure water storage tank the set of circulating valves and also its controlling device is omitted.

The valve for only one controlling group A consists of two sets of control valves with or without a set of circulating valves. The valve sets are located in the bores a to e of the valve body 48. This body has channels, which interconnect the bores a to e and connect same with the pressure water supply and discharge conduits and with the cylinders (Fig. 11)

Cam shafts

102 and 103, designed to act upon the valves, are arranged above the valve body. The controlling of the valves is efl'ected by turning

hand wheels

104 and 105 to the right or to the left (Fig. 10)

arrangement, the different positions of which are shown in Figs. 12 to 15. Fig. 12 shows the balance beam position, when the cylinder groups A and B are in the position of rest. The two

cams

106 and 107, keyed on the

cam shafts

102 and 103 influencing the cylinder groups A and -B, are directed vertically downwards, the balance beam 108 lying horizontally and maintaining the circulating valve 109 in open position. In Fig. 13 the cylinder group A is in operation and the cylinder group B at rest. The cam 106 is horizontal, the cam 107 is directed vertically downwards. The balance beam 108 is inclined, the circulating valve 109 is closed.

If both cylinder groups A and B are controlled, the

cams

106 and 107 and 'the balance beam 108 are in horizontal position, the circulating valve 109 being closed (Fig. 14).

When the cylinder group B is in operative posi- Thecirculating valve is controlled by a balance beam the control of one cylinder group is operative;

the point of the cam is directed downwards or outwards in the horizontal position.

The sets of valves consist of sleeves, which are inserted in the bores of the valve body 48 packed the one relative to the other according to the position of the connecting channels, and are pressed together from above and from below by connection parts provided with screw threads.

The pressure water supplied by the pump 136 passes through the channel 110, which is tangential to the bores 11, b, and 0, into the valve block. A second channel 111, shut off on one side in outward direction, intersects the bores c, d and e so that all five bores a to e communicate with the pressure water.

The discharge water leaves the valve block 48 through channels 112 and 113 (Figs. 8 and 11), which also are tangential to and interconnect all five bores a to e.

The two end faces of the valveblock 48 carry the flange connections for the connecting

pipe conduits

14, 15 and 130, 131 respectively to the cylinders 9 and 57. The

channels

114a and 114b establish the communcation between the pipe connections and the control valve set (Fig. 11). When the cylinder groups A and B are in the position of rest, the two

cams

106 and 107 press the balance beam 108 and thereby the bolt 127 in downward direction (Figs. 9 and 12). distance between the pressure bolt 127 and the circulating valve 109 is so selected that this valve and its auxiliary valve 115 are opened only when the pointsof the

cams

106 and 107 are directed vertically downwards (Fig. 12). In this instance first the valve 115 and then the circulating valve 109 is opened. The pump 136 supplies the pressure water into the waste water receptacle 135 through the pressure water feed 132/110, the circulating valve 109 and the pressure water discharge 112/113a (Figs. 9, 12 and 2). If the upper side of the cylinder 9 (cylinder group A) is to be supplied with pressure water, the hand wheel 104 is turned so that the cam 116 above the control valve set d moves downwards (direction of the arrow 117) (Figs. 9 and 11). The cam 116, as is shown in Fig. 8, presses on to the pressure bolt 118 and moves the same downward. This bolt is standing above the valve piston 119, the inner bore of which serves as guide for the valve cone 120 and the upper end face of which The is constructed as a valve seat for the cone 120. I

The valve piston 119 is guided in a stufiing box 121, so that after the closing of the valve 120 no more pressure water can pass into the pressure water discharge conduit 113. The stroke of the valve piston 119 in upward direction is limited by an annular flange 122. The pressure bolt 118,

during its continued downward movement, comes 3 nel 1140 and the pipe conduit 14 extending therefrom into the upper portion of the cylinder 9 and forces the piston 11 in downward direction (Figs. 1, 8 and 11).

During the downward movement of the cam 116, the cam 106 situated above the circulating valve 0 and the balance beam 108 of the same, turns upwards. The balance beam 108, which is acted upon by a spring 126, moves upwards with the pressure bolt 127 and the

valves

109 and 115 situated thereunder, until these two valves rest on their seats. The communication between the pressure water supply conduit 132 and the discharge conduit 133 is thereby interrupted, so that the pump now works on pressure (Figs. 13 and 1) The cam 116 turns upwards and the cam 106 downwards. The pre-valve 123 and main valve 124, acted upon by the spring 125, and also the valve piston 119 move upwards until the two.

valve cones are in the closing position. Thus, the pressure water supply 132/111 is interrupted. The pressure bolt 118 moves upwards under the influence of a spring 128 arranged in a bore of the bolt 118 and resting on the valve cone 120, until it comes into contact with the cam 116. The water in the cylinder cannot flow out, as the connection with the pressure water discharge conduit 133/113 (Fig. 8) is still interrupted by the valve cone 122 loaded by the spring 128. Thus, the piston 11 together with the pressure plate 6 and the upper die part 19 remain in position. Consequently, it cannot happen that the piston and the parts suspended therefrom by their weight gradually press out the water of the lower portion of the cylinder, wherefrom a slow, but continuous descending movement would result.

During this operation however the cam 106 has again pressed the balance beam 108 downwards, so that at the same time the

valves

109 and 115 are opened and the connection between the pressure water supply conduit 132 and the pressure water discharge conduit 133 is established again. The pump then runs idle (Fig. 12)

If the hand wheel is now turned in the direction of the arrow 129, the valve set A controlling the lower cylinder side will be opened, as already described. The pressure water enters through the pipe conduit 15 into the lower portion 'of the cylinder 9 and forces the piston 11 upwards. The water in the lower portion of the cylinder forces upwards the valve cone 120 in the valve set d, the water can flow out of the cylinder through the pipe conduit extending therefrom, the channel 114, the bore in the valve piston 119, the

- open valve 120 and the channel 113, into the pressure water discharge conduit 133.

I claim:

1. A pressure die-casting machine with uniform control of the movable parts by means of gaseous or liquid pressure media comprising in combination a base, columns extending vertically upwards from said base, a cross head mounted on said columns, a closing cylinder in said cross head, a working cylinder in said base a bracket at the side of said base having vertical slots, a control element shiftable in said slots, a plate on said bracket, a horizontal guide carriage on said plate, a second control element shiftably mounted on said plate, and pipe connections between said cylinders and said control elements said elements adapted to follow the movement of said cylinders without loosening said pipe connections.

2. A pressure die-casting machine as specified in claim 1, comprising in combination with the control element, two sets of valves, two 'cam shafts in said control element adapted to control said two sets of valves, a circulating valve, a spring loaded wedge bolt adapted to control said circulating valve, and a balance beam connected to said cam shafts resting on said bolt adapted to close and open said circulating valve when one or both said sets of valves are opened and closed respectively.

3. A pressure die-casting machine as specified in claim 1, comprising in combination with the control element, a working cylinder, a working piston in said cylinder, a valve piston of said control element communicating with the lower piston space of said cylinder, a pipe conduit between the lower space of said cylinder and said control element having an axial bore, and an auxiliary valve in the bore of said valve piston adapted to completely or partially close during the upward movement of said working piston to form an air cushion in the lower space of said cylinder in said pipe conduit and under said valve piston and to brake the return movement of said working piston.

4. In a pressure die-casting machine with device for controlling the movable parts by means of gaseous or liquid pressure media, the combination of an ejecting plate, rods carrying said ejecting plate, an abutment plate having slots open at one end to accommodate said rods, detachable plates on said abutment plate adapted to hold and guide said rods, screw bolts fixing each one of said detachable plates on said abutment plate, and abutment nuts one on each of said rods adapted to adjust the stroke of said ejecting plate said rods adapted to be removed after removal of said bolts and said detachable plates without changing the adjustment of said abutment nuts.

PAUL HAESSLER.