JPH06142884A - Injection device of die casting machine - Google Patents

Abstract

PURPOSE:To enable the optical setting for the final filling pressure by providing a check valve for opening/closing piping line by switching by a solenoid valve and a relief valve for setting pressure in series in the piping line. CONSTITUTION:In a piston accumulator 13, a cylinder 18 with step, pressure changing piston 15, an accumulator piston 14 and a detection device 152 are provided. A part 30 at pressure increasing side and an oil chamber at injection side of an injection cylinder 10 are communicated with a piping line 57. A hydraulic source 41 and a port 30 at the pressure increasing side are communicated with a piping line 52 through the check valves 53, 54. In a piping line 62, an accumulator 63 connecting the hydraulic source 41 with an end surface part 27 is provided. In a piping line 48, a flow rate adjusting valve 50 and the check valve 49 are provided in series. In a piping line 42, a piping line 45 provided with the check valve 46 for opening/closing the piping line by switching the solenoid valve 47 and the relief valve 47 for setting pressure in series is provided. By this method, the surging generated before the final filling can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device for a die casting machine, and more particularly to high quality die casting with high precision.

[0002]

2. Description of the Related Art Conventionally, for casting metal products, die casting has been used in which molten metal (hereinafter referred to as molten metal) is filled in a cavity of a mold by an injection plunger of an injection cylinder.

In ordinary die-cast molding, the molten metal is set at a low injection speed of about 0.3 m / sec at the start of injection to prevent bubbles from being caught in the molten metal, and the injection speed is set to 3.0 after the head of the molten metal reaches the mold cavity. The cavity is quickly filled at a high speed of about m / sec so that the filling is completed before the molten metal begins to cool and solidify.

[0004]

However, in the die casting operation, the filling speed of the molten metal to be filled in the cavity must be controlled depending on the product thickness or the product volume of the die cast product (hereinafter referred to as product).

That is, the thinner the product thickness of the cast product to be molded, and the larger the product volume, the shorter the filling time in order to prevent cooling and solidification of the molten metal, so the filling speed must be increased.

However, in order to increase the filling speed, it is necessary to increase the amount of pressure oil in the accumulator for controlling the filling speed, but after the molten metal is completely filled in the cavity, the pressure in the cavity is increased in an extremely short time. (This is called surge pressure), so the air in the cavity does not escape,
A gap was created in the cavity, the air in the gap was compressed, the mold clamping force was exceeded, a gap was created in the mating surface of the mold, and the molten metal was scattered outside the mold, which was dangerous. .

Further, since the pressure is generated in the cavity in such a short time, the thickness of the air vent for discharging the gas in the cavity can be formed only in a very thin shape. The gas remaining inside was generated as cavities in the product, which was the cause of making poor castings.

For this reason, there are a composite cylinder system for generating a casting pressure that does not generate a surge pressure, and a run-a-land system in which a piston rod has a rapid filling pressure to increase the diameter of an injection piston. This method is not a means for solving this problem, and a method of decelerating a part before the final filling to eliminate surge pressure was also considered, but it was not a final solution.

If the final filling pressure remains fixed,
Even if it was necessary to change the final filling pressure due to changes in molding conditions, it was not possible to deal with it easily.

The present invention has been made in view of the above problems, and an object thereof is to obtain an injection device of a die casting machine capable of eliminating the generation of surge pressure and arbitrarily setting the final filling pressure. .

[0011]

In order to solve the above-mentioned problems, the present invention provides a pressure increasing chamber 22 and a piston chamber 20 each having a small diameter portion having an inner diameter surface having a groove 191 in the central portion and having large diameters at both ends. Is integrally fixed to the stepped cylinder 18 and the piston 16 slidably fitted to the pressure increasing chamber 22, and slidably fitted to the small diameter portion of the cylinder 18. The end face A on the anti-pist side projects into the piston chamber 20,
Also, the pressure conversion piston 15 is composed of a rod 17 provided with an oil passage 23 communicating from the end face A to the groove 101 of the small diameter portion of the cylinder 18, and is slidably fitted in the piston chamber 20. The piston rod 12 is fixed to the piston accumulator 13 having an accumulator piston 14 that can be brought into contact with the end surface A of the valve 15, and a pressure increasing chamber 22 and a detection device 152 that detects the amount of pressure oil accumulated in the piston chamber 20. The injection cylinder 10 in which the injection piston 11 is slidably fitted, the pressure increasing port 30 provided in the pressure increasing chamber 22 of the piston accumulator 13, and the injection cylinder 1
Opening and closing are performed by switching the electromagnetic switching valve 56 between the hydraulic pressure source 41 and the pressure increasing side port 30 and the pipeline 57 communicating between the 0 injection side oil chambers via the flow rate adjusting valve 58 with a check valve. A conduit 52 communicating with the check valve with pilot 53 and the check valve 54, a conduit 62 having a pressure storage device 63 connecting the hydraulic pressure source 41 and the end surface port 27 of the piston chamber 20, and a small diameter portion of the piston accumulator 13. A pipe line 48 in which a flow rate adjusting valve 50 and a check valve 49 are connected in series between the port 26 in the groove 191, the injection cylinder 10 and the flow rate adjusting valve 58 with a check valve, and a hydraulic pressure source 41.
Has an electromagnetic switching valve 43 that connects the end port 28 of the piston accumulator 13 near the small diameter portion of the piston chamber 20, and branches at the outlet of the end port 28 to switch the line by switching the electromagnetic switching valve 43. The injection device for a die casting machine is provided with a pipe line 42 having a pipe line 45 in which a check valve with pilot 46 for opening and closing and a relief valve 47 for pressure setting are provided in series.

[0012]

In casting, in order to move the piston of the injection cylinder forward, the accumulator piston is pushed by the accumulator until it comes into contact with the piston rod end surface A, and the accumulator piston comes into contact with the piston rod.
The supply of pressure oil to the injection cylinder is stopped, and then the forward movement of the pressure conversion piston pushes the piston of the injection cylinder at high pressure.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 3. Reference numeral 10 is an injection cylinder of a die casting machine (not shown), which has an injection piston 11 inside and a plunger for pushing molten metal into a mold cavity at its tip. A piston rod 12 fitted with a tip (not shown) is fitted.

A pressure-increasing port 30 of a piston accumulator 13 for increasing pressure is provided in the injection-side oil chamber of the injection cylinder 10.
Are connected via a flow rate adjusting valve 58 with a check valve that adjusts the opening amount of the check valve.

The piston accumulator 13 is a small diameter portion having an inner diameter surface having a groove 191 and both end portions having large diameter pressure increasing chambers 22.
And the stepped cylinder 18 that has become the piston chamber 20
And the piston 1 slidably fitted in the pressure increasing chamber 22.
6 is integrally fixed to the cylinder 6, slidably fitted to the small diameter portion of the cylinder 18, the end face A on the side opposite to the piston projects into the piston chamber 20, and the cylinder thin portion from the end face A. Rod 1 provided with an oil passage 23 communicating with the groove 191 of
Pressure conversion piston 15 composed of 7 and the piston chamber 2
An accumulator piston 14 slidably fitted to 0 and capable of contacting the end surface A of the pressure conversion piston 15,
A piston rod 151 having one end fixed to the end face of the piston 16 and the other end protruding outside the piston accumulator 13
And a detection device that detects the amount of oil supplied to the piston accumulator 13 by a piston sensor 152 that measures the displacement.

A pipe 52 in which a pilot check valve 53 and a check valve 54 are connected in series is connected to the pressure-increasing port 30 and is opened and closed by switching an electromagnetic switching valve 56 from a hydraulic pressure source 41, and a cock 64 is connected. A maintenance pipeline 61 having the above is provided in parallel with the pipeline 52.

To the piston chamber 20, there is connected a pipe line 62 which is led out from a hydraulic pressure source 41 through a port end face 27 and provided with a pressure storage device 63, and the gas pressure in the pressure storage device 63 acts on the piston chamber. When the molten metal in the sleeve (not shown) is injected, the accumulator piston 14 is pushed downward in the figure.

In the groove 191 on the inner diameter surface of the piston accumulator 13, a pipe line 48 in which a flow rate adjusting valve 50 and a check valve 49 are connected in series is led out through a port 26, and the injection cylinder 10 and the flow valve 58 with a check valve are connected. In communication with each other. A port end 28 is provided at the end of the piston accumulator 13 on the side of the small diameter portion of the piston chamber 20,
A pipe line 42 from the hydraulic pressure source 41 communicates with each other via an electromagnetic switching valve 43 and a check valve 44.

A pipe 45 connected to a pressure change relief valve 47 for setting the set pressure in the piston chamber 20 and a pilot-equipped check valve 46 for opening and closing the pipe by switching the electromagnetic switching valve 43 is formed. It branches from between the check valve 44 and the end port 28.

The above-mentioned construction is described. Next, the operation thereof will be described. First, during casting, pressure oil is supplied to the accumulator 63 in order to supply pressure oil to the piston accumulator 13 in advance. At the same time, the electromagnetic switching valve 56 is excited to the left position, the pilot check valve 53 is opened, pressure oil is supplied from the pipe line 52 to the pressure increasing chamber 22, and the piston chamber 20 is supplied from the pipe line 42. Supply pressure oil to. At this time, the flow rate adjusting valve 50 is closed,
The conduit 48 is in a closed state. Therefore, the accumulator piston 14 of the piston accumulator 13 is the accumulator 63.
It is pushed up to the uppermost part of the piston chamber 20 in the figure against the gas pressure of.

When a predetermined amount of pressure oil is accumulated in the piston accumulator 13, the sensor 152 senses it and the electromagnetic switching valve 56 is in the neutral position, and the pilot check valve 53 is operated by the pilot. The pressure no longer acts and the pilot check valve 53 is closed. Similarly, the electromagnetic switching valve 43 is also non-excited, and the pressure oil from the hydraulic pressure source 41 is no longer supplied to the piston chamber 20.

Thus, the storage pressure of the piston accumulator 13 is completed.

Next, in the injection process, the piston 11 of the injection cylinder has a low injection speed (0.3 m / sec) at the start of injection.
When the flow rate adjusting valve 50 is opened so as to move at
The accumulator piston 14 is pushed by the gas pressure of the accumulator 63 and moves downward in the figure, and the pressure oil in the piston chamber 20 acts on the oil chamber of the injection cylinder 10 through the pipe line 48. During this period, the check valve-equipped flow rate adjusting valve 58 is closed by the pilot pressure from the conduit 48, so that the pressure oil in the pressure boosting chamber 22 does not flow out to the injection cylinder 10.

After passing a predetermined low speed range, the opening of the flow rate adjusting valve 50 opens for high speed, the flow rate of the pressure oil passing through the flow rate adjusting valve 50 also increases, and the piston 11 also moves quickly. The injection of no molten metal into the mold is done at high speed.

The accumulator piston 14 has a rod 17
When the piston chamber 20 comes into contact with the end surface A of the
The pressure oil that had been separated into 2 and has flowed from the piston chamber 20 through the groove 191 to the pipe line 48 until now stops flowing, and the piston 1
The movement of 1 also stops. When the flow of pressure oil in the pipeline 48 is stopped, the pilot pressure acting on the check valve-equipped flow rate adjusting valve 58 and the pilot check valve 46 disappears, and both valves 58 and 46 open the pipeline, so the pressure increasing chamber 22
The pressure oil inside is pushed by the pressure conversion piston 15 and at the flow rate set in the flow control valve with check valve 58, the injection cylinder 10
, And the piston 11 starts moving again.

Next, the pressure change of the pressure oil before and after the pressure conversion piston 15 will be described with reference to FIG. Here, the area of the accumulator piston 14 is A2, the pressure of the chamber 201 is P2, the area of the accumulator piston 14 less the area of the rod 17 is A1, the pressure of the chamber 202 is P1, and the area of the piston 16 is A3. The pressure in the pressure boosting chamber 22 is P3. A
The relationship between 1, A2, and A3 is provisionally set to the following conditions. From A2 = 2,5A3, A2-A1 = 0, 8A3, A1 = 1, 7A3. When the accumulator piston 14 comes into contact with the rod 17, there is no flow to the oil passage 23, so the check valve with pilot 46 and the flow rate adjusting valve with check 58 are opened.
At this time, the relationship of forces is A2P2-A1P1 = A3P3.

P3 = (A2P2-A1P1) / A3 = (2.5 A3P2-1.7 A3P1) /A3=2.5 P2-1.7 P1 Below, it is examined how many times P3 becomes P2. K = P3 / P2 = 2.5 −1.7 P1 / P2 Where P2 = 150 Kgf / mm K = 25−1.7 P1 / 150 P1 (pressure conversion relief valve 47) = 10 Kgf / mm K = 2.39 Opening adjustment pressure = 30 ＝ 2.16 ＝ 60 ＝ 1.82 ＝ 120 ＝ 1.14 ＝ 132 ＝ 1.00 ＝ 150 ＝ 0.80 ＝ 180 ＝ 0.46 P1 (depending on the opening adjustment of the pressure conversion relief valve 47) changes P3 against P2 (pressure in the oil chamber 201) ( It can be seen that the value of the pressure in the pressure increasing chamber 22) changes greatly.

Therefore, in order to generate the amplification power, P1 = 132
When the pressure is Kgf / mm or less, the large pressure P3 amplified amplifies the piston 11.

The pressure oil in the oil chamber 202 returns to the tank 40 via the pilot check valve 46 and the pressure conversion relief valve 47, and the pressure set in the pressure conversion relief valve 47 becomes the final filling pressure of the injection cylinder 10. .

[0030]

As described above, when the accumulator piston 14 comes into contact with the rod 17, the piston 11 is temporarily stopped, so that the surging which occurred before the final filling, which has conventionally occurred, is eliminated, and the final filling is further performed. The pressure can now be set arbitrarily.

[Brief description of drawings]

FIG. 1 is a diagram showing an injection cylinder, a piston accumulator, and a hydraulic circuit related thereto, which constitute an injection device of a die casting machine according to the present invention.

FIG. 2 is a detailed view of the pressure conversion piston in the piston accumulator.

FIG. 3 is a schematic diagram illustrating a pressure increasing mechanism in a pressure converting piston.

[Explanation of symbols]

 10 Injection Cylinder 11 Injection Piston 12 Piston Rod 13 Piston Accumulator 14 Accumulator Piston 15 Pressure Conversion Piston 16 Piston 17 Rod 40 Tank 41 Hydraulic Source 46 Pilot Check Valve 47 Pressure Conversion Relief Valve 50 Flow Control Valve 58 Flow Control Valve with Check

[Procedure amendment]

[Submission date] January 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

P3 = (A2P2-A1P1) / A3 = (2.5 A3P2-1.7 A3P1) /A3=2.5 P2-1.7 P1 Below, it is examined how many times P3 becomes P2. K = P3 / P2 = 2.5 −1.7 P1 / P2 where P2 = 150 Kgf / cm ² K = 25−1.7 P1 / 150 P1 (pressure conversion relief valve 47) = 10 Kgf / cm ² K = 2.39 Opening adjustment pressure = 30 = 2.16 = 60 = 1.82 = 120 = 1.14 = 132 = 1.00 = 150 = 0.80 = 180 = 0.46 P3 due to a change in P1 (depending on the opening adjustment of the pressure conversion relief valve 47), P3 against P2 (pressure in the oil chamber 201) It can be seen that the value of (pressure in the pressure boosting chamber 22) greatly changes.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

Therefore, in order to generate the amplification power, P1 = 132
The piston 11 is pressed by the large pressure P3 amplified by setting the pressure to be less than kgf / cm ² .

Claims (1)

[Claims] 1. A stepped cylinder 18 having a small diameter portion whose inner surface has a groove 191 in the central portion and large diameters at both ends, and a stepped cylinder 18 and a piston chamber 20. The piston 16 is slidably fitted to the piston 16 and is slidably fitted to the small-diameter portion of the cylinder 18, and the end face A on the side opposite to the piston protrudes into the piston chamber 20.
Also, the pressure conversion piston 15 is composed of a rod 17 provided with an oil passage 23 communicating from the end face A to the groove 101 of the small diameter portion of the cylinder 18, and is slidably fitted in the piston chamber 20. The piston rod 12 is fixed to the piston accumulator 13 having the accumulator piston 14 that can be brought into contact with the end surface A of the piston 15, and the pressure increasing chamber 22 and the detection device 152 that detects the amount of pressure oil accumulated in the piston chamber 20. The injection cylinder 10 in which the injection piston 11 is slidably fitted, the pressure adjusting port 30 provided in the pressure increasing chamber 22 of the piston accumulator 13 and the injection side oil chamber of the injection cylinder 10, and the flow rate adjusting valve with a check valve. Conduit 57 communicating through 58
And the electromagnetic switching valve 5 between the hydraulic pressure source 41 and the pressure increasing side port 30.
A check valve 53 with a pilot for opening and closing by switching 6 and a conduit 52 communicating through a check valve 54.
A pipe line 62 having an accumulator 63 connecting the hydraulic pressure source 41 and the end face port 27 of the piston chamber 20, a port 26 in the groove 191 of the small diameter portion of the piston accumulator 13, the injection cylinder 10 and a flow adjustment with a check valve. A pipe line 48 connected in series between a valve 58 and a flow control valve 50 and a check valve 49 is connected to an oil pressure source 41 and an end port 28 of the piston accumulator 13 near the small diameter portion of the piston chamber 20. A pipe having an electromagnetic switching valve 43, which is branched at the outlet of the end port 28 and in which a check valve with a pilot 46 and a pressure setting relief valve 47, which are opened and closed by switching the electromagnetic switching valve 43, are provided in series. An injection device for a die casting machine comprising a conduit 42 having a conduit 45.