DE2634830C2 - Casting unit for a die casting machine - Google Patents

Description

The invention relates to a casting unit for a die-casting machine, comprising a working piston which can be displaced in a working cylinder and an in a multiplier cylinder displaceable and with its smaller diameter section in the working space of the working cylinder nii <einrs> lowing multiplier piston, in the Arbeitsraul.1 one outside of the The pressure medium supply line, which runs through a multiplier piston and can be shut off by a check valve, is used to supply a working piston during a first and a second working phase of the die casting machine discharges pressure medium.

A casting unit of this type is known from DE-OS 21 65 929. In this known casting unit is ( Although it is possible to open the multiplier piston independently of the closing of the check valve in the Pressurize the pressure medium line and set it in motion before the end of the second injection phase. However, it is not possible to precisely control when the multiplier piston is in its rest position leaves and how far the multiplier piston has moved. before in the working space of the working cylinder the desired system pressure is present.

The invention is based on the object of designing a casting unit of the type mentioned at the outset in such a way that that the multiplier movement are monitored can.

According to the invention, this object is achieved by that the side of the multiplier piston facing away from the working space is acted upon by a spring-loaded stylus. the other end to one of the Display of the position of the multiplier piston serving limit switch is connected.

The movement of the stylus can be used to determine exactly when the multiplier piston is working Leaves rest position and how far he has moved. If in the path of the pressure medium between Working piston and check valve, a pressure transducer is arranged. can be an exact relationship / wipe the one covered by the multiplier piston The path and the achieved system pressure. These Control of the multiplier movement is extremely important for the consistent quality of die castings, as a change in this relationship j hung indicates a change in the casting conditions in the course of successive casting processes.

The invention is explained below with reference to a single figure, which is a semi-schematic Representation of the casting unit according to the invention shows, lu In a working cylinder 1 of a casting unit A working piston 2 with a piston rod 3 is displaceably guided in the die casting machine. Fixedly connected to the piston rod 3 is a not shown Plunger with which the metal is pressed into the die-casting machine's form, also not shown will. The working cylinder 1 is followed by a multiplier cylinder 4 in which a multiplier piston 5 is displaceably guided Upstream of 5 is a compressor prestressing space 6, which is connected to a bladder accumulator 8 via a line 7 connected is.

In the working space 11 of the working cylinder 1 opens a pressure medium supply line 9 in which a check valve 10 is arranged. To that - in the direction of flow 2ϊ considered - lying in front of the check valve 10 Part of the pressure medium supply line 9 closes a connecting line 13 coming from a pump line 12 at.

In the first phase, hydraulic medium is drawn from a w Pump conveyed via line 12, 13. Consequently the closure member 14 of the check valve 10 is pressed against the pressure of a spring 15 in its open position and the working piston 2 in the direction of the Arrow P shifted.

After the metal has been advanced into the mold during the first phase, the piston rod 3 actuates a switch (not shown) that controls a directional valve 16 after having covered a defined distance. The directional control valve 16 in turn initiate! jftt the opening of pilot valves 16.1 ... 16.5. through which the opening path of a valve cone 17 of a digital quantity control device 24 and thus the piston speed during the second phase are determined Line 1}. Opens the closure piece 14 and acts on the working piston 2.

Towards the end of the / dwell phase, the third phase may be formed by time, pressure or road speed controlled τ "directional control valve are introduced 19th Snh.il ·! ·. If the directional valve 19 is in the working position, the desired opening path for a valve cone 20 of a digital flow control device 25 would suddenly be released, since a valve combination on pilot valves 20.1 ... wide phase was discontinued.

The hydraulic medium for this phase flows from the piston accumulator 18 via a line 21 and acts on the multiplier piston 5, which then ^{leaves its h0} rest position.

As soon as the pressure towards the end of the working space 11 Mold filling increases, the spring 15 pushes the Closure piece 14 on the valve seat so that the Pressure amplification without delay without a pressure spike

"" 'begins.

In order to set the desired final pressure for the pressure amplification, after digital preselection on Control panel of the die casting machine from a printing

Gel device 23 of the boost pressure is set and by means of a directional control valve 22 from the Vorsieuerventilen 20.1 ... 203 lifted off.

The inflow of hydraulic medium from the piston accumulator 18 and thus the piston speed for the second and third press-in phases are accordingly carried out on the digital quantity control devices 24 and 25, respectively set the values preselected on the control panel of the die casting machine, while the boost pressure for the cias memory 8 and thus the final pressure resulting from the multiplication accordingly the selected preselection is called up by the digital pressure control device 23. As for the second and A separate quantity control device is provided in each case for the third EinpreQphase, can for example via the Quantity control device 25, if necessary, a larger amount of oil per unit of time for the third injection phase can be called up than was the case during the second press-fit phase. There can thus be a rapid build-up of pressure can also be achieved with a slow mold filling phase.

In the multiplier cylinder 4 is a spring-loaded Built-in stylus 26, which acts on the side of the multiplier piston 5 facing away from the working piston 2 and interacts with a limit switch 27. The spring-loaded stylus follows the movement of the Multiplier piston, so that in connection with the limit switch 27 it can be determined exactly when the Multipiikatorkolben 5 leaves its rest position and how far it moves.

In the line 9 between the working space 11 and A pressure transducer 28 is built into the check valve 10. In conjunction with the spring-loaded It gives stylus 26 the ability to measure precisely and monitor whether and how far the multiplier col-

¹⁵ ben 5 has left its rest position before the desired system pressure is available in the working space 11

was previously not possible without great effort.

For this purpose I sheet drawings

Claims (2)

Patent claims: 1. Einpreßieil for a die casting machine, comprising a displaceable in a working cylinder Working piston and one in one. Multiplier cylinder displaceable and with its smaller-diameter section protruding into the working space of the working cylinder multiplier piston, in the working space a outside of the A pressure medium supply line that runs through a multiplier piston and can be shut off by a non-return valve for feeding the working piston during a first and a second working phase of the Pressure medium acting on the die casting machine opens, characterized in that the the working space (11) facing away from the multiplier piston (5) by a spring-loaded The feeler pin (26) is applied, the other end of which actuates one of the limit switches (27) to display the position of the multiplier piston (5). 2. Pressed in :! according to claim!. characterized in that in the path of the pressure medium A pressure sensor (28) is arranged between the working piston (2) and the check valve (10).