GB1569382A - Low pressure die-casting machine - Google Patents

Description

(54) LOW PRESSURE DIE-CASTING MACHINE (71) We, SPETSIALNOE KON STRUKTORSKOE BJURO MASHIN TOCHNOGO LITYA PRI TIRASPOLS KOM ZAVODE LITEINYKH MASHIN IMENI SM. KIROVA, of ditsa Sakriera, 2v, Tinaspol, and INSTITUT PROBLEM LITYA ARADEMII NAUK UKRAIN SKOI SSR, of prospekt Vernadskogo, 34/1, Kiev, both Union of Soviet Socialist Republics, both Corporations organised and existing under the laws of the Union of Soviet Socialist Republics, do hereby declare the invention, for which we pray that a patent way be granted to us, and the method by wtch it is to be performed, to be pariicuFarDy described in and by the following statement: The present invention relates to low pressure die-casting machines. The invention can be advantageously used in foundry practice where inechanized means are employed for opening and dosing dies of low pressure arPcasting cfJes.

A known low-pressure die-casting machine camprises dies whose half-dies have vertical jaint faces, an actuator for halfdies, a device for filling the dies with molten metal under gas pressure and a device for easing the dies and ejecting castings with pusher plates, ejector pins and pusher rods. The pusher plates are connected to power-driven pusher rods and twxFarm levers in such a manner that on opening a die by bringing apart its haf-dies, it is first eased off, with the casting being held in position by the ejector pins and fflen, upon turning the twocarm lever, the die is opened wide apart and the ejector pins are retracted. The casting remains seated in the metal conduit within the joint face of the die; it is removed either with the help of a special lifting device or by hand.

In the prior-art machines, each die is in dividually furnished with a device for easing the dies and ejecting castings, which makes the machines cosdy and complicated in operation if the dies are increased in number.

In these machines, the removal of castings is the most labour-consuming and inefficient operation. This is due to the fact that the device for easing the dies and ejecting castings is a rather intricate system called upon to successively perform the operations of easing and opening half-dies, of the both halfdies simultaneously, whereupon the ejector pins are backed away, with the castings remaining in an unstable position. Another reason for this is a need for an additional either mechanical or manual casting handling operation.

According to the invention, there is provided a low-pressure die-casting machine, comprising dies whose half-dies have vertical joint faces, each die including a stationary half-die and a movable half-die, the stationary half-dies being paired, with their backs towards one another, actuators for moving the movable half-dies, an arrangement for filling said dies with molten metal, and a device for easing the dies and ejecting castings, said device comprising pusher plates arranged between the back faces of the stationary half-dies, pusher rods extending between the pusher plates, ejector pins for ejecting castings, and rods for easing dies, the device being arranged so that the pusher rods can be actuated on to substantially simultaneously actuate the ejector pin or pins and rods associated with one die.

Such construction of the proposed lowpressure die-casting machine ensures sub stantially simultaneous operations of easing the dies and ejecting a casting from a stationary half-die, with the casting remaining in the movable half die. This in turn, facilitates the operation of removing the casting for its subsequent transport.

Inasmuch as the low-pressure die-casting process is characterised by a relatively extended time for producing castings, which is due to prolonged filling of the dies and a relatively long time required for the solidi fication of the castings, especially of thickwalled ones, the knawn machines are therefore not highly efficient.

The proposed invention makes it possible to enhance efficiency of such machines, since simpler construction of a device for. easing the dies and ejecting castings permits two or more dies to be utilised simultaneously.

According to one embodiment, a lowpressure die-casting machine has two dies arranged coaxially so that when one of the dies is open, the other is closed, the device for easing the dies and ejecting castings being actuated by a movable half-die closing one of the dies.

According to another embodiment a powerdriven wedge having at least two working faces is provided to act on the pusher rods.

Such arrangement permits several castings to be produced simultaneously.

The invention will be better understood from the following detailed description which is given by way of example, of preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a front elevation view of a lowpressure die-casting machine according to one embodiment of the invention, showing in a vertical section an arrangement for filling the dies with molten metal; Fig. 2 is a plan view of the machine of Fig. 1, with an axial horizontal section of a device for easing the dies and ejecting castings; Fig. 3 is a front elevation view of a lowpressure die-casting machine according to another embodiment of the invention, showing in a vertical section an arrangement for filing the dies with molten metal and a device for easing the dies and ejecting castings; Fig. 4 is a plan view of the machine of Fig. 3 with an axial horizontal section of a device for easing the dies and ejecting castings; and Fig. 5 is a vertical cross-sectional view of part of the machine of Figure 3 showing an eased off die in which a casting has been ejected from a stationary half-die.

Referring now to the drawings, there is shown therein a low-pressure die-casting machine which comprises dies 1 and 2 whose half-dies 3, 4 and 5, 6 respectively, have vertical joint faces, actuators 7 and 8 for half-dies, an arrangement for supplying the dies with molten metal including a reservoir or furnace crucible 9 and conduits 10 for delivering molten metal into each die, as well as a device for easing the dies and ejecting castings, which has pusher plates 11 and 12, ejector pins 13 and 14, and pusher rods 15.

Each die 1 and 2 is provided with movable half-dies 3 and 5 and stationary half-dies 4 and 6 respectively. The stationary half-dies 4 and 6 are arranged with their back towards one another and the pusher plates 11 and 12 of the device for easing the dies and ejecting castings are each arranged behind the respective stationary half-dies, i.e. between the two stationary half-dies 4 and 6, as shown in Figs.

2, 3 and 4. The pusher plates 11 and 12 are interconnected by the pusher rods 15 and provided with rods 16 and 17 for easing the dies apart. The ejector pin 13 and rods 16 operate simultaneously, said pin and rods having lengths enabling them to establish substantially simultaneous contact with a casting and a movable half-die, respectively. Similarly, the pin 14 and rods 17 operate simultaneously.

In accordance with one embodiment of the invention, shown in Figs. 1 and 2, a lowpressure die-casting machine comprises a base plate 18 with a crucible 9 having two conduits 10. An actuator 8 for closing the right-hand die 2, as illustrated in the drawing, and an actuator 7 for closing the left-hand die 1 are mounted on the base plate 18. The actuators 7 and 8 are basically conventional hydraulic cylinders. A piston rod 19 of the actuator 7 is fitted with a plate 20 adapted to carry a movable half-die 3, and a piston rod (not visible since it is in the retracted position) of the actuator 8 is fitted with a plate 21 adapted to carry a movable half-die 5. Between the movable half-dies 3 and 5 there is a bed plate 22 mounting stationary half-dies 4 and 6 which are arranged with their backs towards each other. The above half-dies brought close together, form two dies 1 and 2 respectively.

A device for easing the dies apart and ejecting castings is mounted on the stationary bed plate 22 and includes pusher plates 11 and 12 carrying ejector pins 13 and 14, and rods 16 and 17 for easing the dies. The number of said ejector pins and rods as well as their length, is dependent on the casting configurations and each set of pins and rods is designed for substantially simultaneous operation when the dies are being opened.

The pusher plates 11 and 12 are interconnected by pusher or tie rods 15 extending through the bed plate 22. In both cases, rigid connection between the pusher plates 11 and 12 is provided to enable their reciprocated movement.

Between the conduits 10 and the dies 1, 2 a means 23 is provided for cutting off the metal supply. The means 23 has gate valves 24 movable in the direction normal to the axes of the conduits 10. Mounted on a plate 25 arranged on supports 26, are two devices 27 with piston rods which extend into the dies for additional compressing of metal in the dies. The molten metal supply cut-off means and the compression devices are not described in detail inasmuch as they are not part of the invention and are used by way of illustration only. The molten metal supply cut-off means makes it possible to isolate the die cavity, filled with molten metal, from the crucible 9 which is essential for producing a requisite pressure in the course of the casting compacting operation, and for making it possible to horizontally transfer a finished casting from the die filling station to the casting removal station. The low-pressure diecasting machine is shown in the drawings as having the left-hand die closed and the righthand die opened, the flow of molten metal in the right-hand conduit 10 being cut off with the gate valve 24 of the molten metal supply cut-off means. This is one of the two positions the machine can assume; in the other position the left-hand die is opened and the right-hand die dosed.

In operation, a flow of gas under pressure is fed to the crucible 9 to force the molten metal up the left-hand open conduit into the die 1. Upon filling the die 1, the molten metal supply cut off means 23 is actuated, and one of the gate valves 24 closes to disconnect the conduit 10 from the die gate channel. The appropriate compression device 27 is then actuated to effect additional com- pression of the metal in the left-hand die 1, thereby creating the excessive pressure required to contact the solidifying metal.

After the metal has been solidified,the cores are knocked out and the piston rod of the compression device retracted with an auto- matic contra system (not shown) producing a signal to dose the right-hand die 2. At the end of the dosing movement of the righthand die 2 the movable half-die 5 collides with the rods 17 and pushes the whole die casing and casting ejection device, i.e. the rods 17, the pusher plate 12, the pusher rods 15, the pusher plate 11, the rods 16 and the ejector pins 13 to the left. At the instant of dosing the right-hand die 2, the pressure in the hydraulic cylinder of the actuator 7 is released and the rods 16 push away the half die 3, while the ejector pins 13 ejeot the casting from the stationary half-die 4, the casing being left in the movable half-die.

lf necessary the casting ejection operation can be slightly retarded upon completion of the die easing operation. For this purpose, the ejector pins 13 are made shorter in length.

Now a signal for opening the left-hand die is transmitted to the aotuator 7, the casting is carried in the movable half-die 3 to be ejected therefrom at the end of the opening movement into a receptacle or directly onto a conveyor. The casting is ejected from the movable half-die with the aid of a well-known device not herein described.

As soon as the right-hand die 2 is closed, a signal is produced to shift the gate valve 24 of the molten metal supply cut-off means 23 to communicate the interior of the righthand conduit 10 with the cavity of the die 2.

At this time, the valve 24 of the molten metal supply cutoff mechanism 23 for the left-hand die keeps its conduit closed. Then, pressure in the orucible 9, which was released after discommunication of the conduit from the gate channel of the die 1, is built up and further operation proceeds in a manner similar to that described above.

Therefore, upon completing the solldifi- cation process in one die, the latter is eased off and the casting is ejected from the stationary half-die by virtue of the closing movement of the other die. The device for easing the dies and ejecting castings, which is simple in construction, makes it possible to utilize two dies, each with one stationary half-die incorporated therein, in a low pressure die-casting machine, and facilitates the casting removal and its further handling eliminating the need for manual operations and auxiliary mechanisms.

According to another embodiment of the invention shown in Figs. 3, 4 and 5, there is arranged between the pusher plates 11 and 12 a hollow box-like bed plate 28 having walls with pusher rods 29 and 30 reciprorably extended therethrough. The pusher rods 29 and 30 come into contact with a power-driven wedge 31 extending through the interior of said bed plate 28 perpendicular to the plane of the pusher rods 29 and 30. In this em bodiment of the invention the wedge 31 has two working faces which interact with the pusher rods 29 and 30. However the wedge 31 may comprise more than two working faces interacting with a corresponding number of the pusher rods, for example, four, six etc.

The wedge 31 is actuated by a cylinder 32 attached to the plate 25. Figs. 3 and 4 show the lowzpressure die-casting machine with both dies closed.

In operation, a flow of gas under pressure is fed to the crucible 9 to force the metal up the conduit 10 through openings in gate valves 24 into both the dies simultaneously (the pressure system is not shown as It does not constitute a part of this invention). When the dies are filled with the molten metal, the cut-off means 23 with the aid of the gate valves 24, cuts off the metal supply, discommunicating the conduits 10 from the respective die gate channels. Thereafter the compression means 27 is actuated to build up pressure required to compress the metal being solidified in both the dies. Upon completion of the solidification process, the pressure in the hydraulic cylinders of the actuators 7 and 8 is released and the piston rods of the com- pression means 27 are withdrawn from the dies.

Then the power-driven wedge 31 moving downwards, transmits the effort for easing the stationary halfdies 4 and 6 through the pusher rods 29, the pusher plate 11, the rods 16 and the ejector pin 13, acting simultaneously on the movable half-die 3 and on a casting, and through the pusher rods 30, the pusher plate 12, the rods 17 and the ejector pin 14 acting simultaneously on the movable half-die 5 and on the casting. In this way both the dies are eased off simultaneously, with the castings being ejected from the stationary half-dies 4 and 6 and fixed in position in the movable half-dies 3 and 5.

Next, pressure is built up in the cylinders of the actuators 7 and 8, as well as in the cylinder 32; thereby causing the opening of the dies and retraction of the wedge 31.

The castings are moved in the movable half-dies 3 and 5 and ejected therefrodn at the end at the opening cycle. Upon completion of ejection of the casting a signal for closing the dies is produced and the casting cycle is repeated as hereinbefore disclosed.

This simple device for easing the dies and ejecting castings ensures that the castings are retained in the movable half-dies in which they are readily conveyed to a removal station.

WHAT WE CLAIM IS: 1. A low-pressure die-casting machine, com- prising dies whose half-dies have vertical joint faces, each die including a stationary half-die and a movable half-die, the stationary half-dies being paired, with their backs towards one another, actuators for moving the movable half-lies, an arrangement for filling said dies with molten metal, and a device for easing the dies and ejecting castings, said device comprising pusher plates arranged between the back faces of the stationary halfdies, pusher rods extending between the pusher plates, ejector pins for ejecting castings, and rods for easing dies, the device being arranged so that the pusher rods can be acted on to substantially simultaneously actuate the ejector pin or pins and rods associated with one die.

2. A machine as claimed in claim 1, wherein a power-driven wedge having at least two working faces is provided to act on the pusher rods.

3. A machine substantially as hereinbefore described with reference to, and as shown in, Figures 1 and 2 or Figures 3 to 5 of the accompanying drawings.

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

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. the pusher plate 12, the rods 17 and the ejector pin 14 acting simultaneously on the movable half-die 5 and on the casting. In this way both the dies are eased off simultaneously, with the castings being ejected from the stationary half-dies 4 and 6 and fixed in position in the movable half-dies 3 and 5. Next, pressure is built up in the cylinders of the actuators 7 and 8, as well as in the cylinder 32; thereby causing the opening of the dies and retraction of the wedge 31. The castings are moved in the movable half-dies 3 and 5 and ejected therefrodn at the end at the opening cycle. Upon completion of ejection of the casting a signal for closing the dies is produced and the casting cycle is repeated as hereinbefore disclosed. This simple device for easing the dies and ejecting castings ensures that the castings are retained in the movable half-dies in which they are readily conveyed to a removal station. WHAT WE CLAIM IS:

1. A low-pressure die-casting machine, com- prising dies whose half-dies have vertical joint faces, each die including a stationary half-die and a movable half-die, the stationary half-dies being paired, with their backs towards one another, actuators for moving the movable half-lies, an arrangement for filling said dies with molten metal, and a device for easing the dies and ejecting castings, said device comprising pusher plates arranged between the back faces of the stationary halfdies, pusher rods extending between the pusher plates, ejector pins for ejecting castings, and rods for easing dies, the device being arranged so that the pusher rods can be acted on to substantially simultaneously actuate the ejector pin or pins and rods associated with one die.

2. A machine as claimed in claim 1, wherein a power-driven wedge having at least two working faces is provided to act on the pusher rods.

3. A machine substantially as hereinbefore described with reference to, and as shown in, Figures 1 and 2 or Figures 3 to 5 of the accompanying drawings.