JPH0212666B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to an injection molding device such as a vertical die casting machine, a squeeze casting machine, a molten metal molding machine, etc. when injecting molten metal into the mold. This invention relates to a method for joining an injection sleeve to a mold to be joined.

[Conventional technology]

In a vertical die casting machine that pours molten metal from directly below the mold, the injection sleeve into which the molten metal is supplied in an inclined position is brought into a vertical position under the mold and then raised by hydraulic pressure, etc. The molten metal is charged into the sleeve hole of the mold, and when the charging is completed, the plunger tip is advanced within the injection sleeve and the molten metal is injected into the mold cavity. In this case, the surface of the molten metal supplied into the injection sleeve in an inclined state is far below the upper end surface of the injection sleeve, and when the injection sleeve is stood vertically, the upper surface of the molten metal is the upper end surface of the injection sleeve. This means that it is now in a lower position than the previous one. and,
Wait until the molten metal in the cavity solidifies and cools down, then open the mold and take the product out of the machine. Injection is performed in the same manner in squeeze casting and molten metal forging.

[Problem that the invention seeks to solve]

In the injection operation using such injection molding equipment, when injecting, the plunger tip pushes up the molten metal that is well below the upper end surface of the injection sleeve and the entrance of the mold cavity. It takes that much more time to push up the molten metal, and the temperature of the molten metal decreases by that amount. If the temperature of the molten metal decreases in this way during injection, the viscosity of the molten metal increases and the flow within the mold cavity becomes poor, so it is necessary to minimize the temperature drop of the molten metal before injecting it into the mold cavity. has become an important issue in improving the quality of molded products.

The present invention was made in view of the above points, and an object of the present invention is to provide a method for joining an injection sleeve to a mold, which shortens the injection cycle and minimizes the temperature drop of the molten metal. There is.

[Means for solving problems]

In order to achieve this purpose, in the present invention, while the vertical injection sleeve is rising after being supplied with molten metal, the plunger tip is advanced at a speed faster than the rising speed so that the molten metal does not overflow from the upper end of the injection sleeve. When the injection sleeve starts charging, the forward speed of the plunger tip is reduced to approximately the same speed as the injection sleeve charging speed, and when the injection sleeve is fully connected to the mold sleeve hole, the injection starts. The upper end surface of the molten metal in the sleeve is positioned near the upper end of the injection sleeve.

[Effect]

When the injection sleeve starts to rise, a detector detects the position of the plunger tip and sends a signal to the hydraulic system, and the plunger tip starts moving forward at a faster speed than the charging speed of the injection sleeve, pushing up the molten metal. Let's do it. When the upper end of the injection sleeve reaches the entrance of the sleeve hole, a signal from the detector reduces the advancing speed of the plunger tip to approximately the same as the injection sleeve loading speed, and this speed continues until the injection sleeve is fully loaded. Then injection into the cavity begins. When the charging of the injection sleeve is completed, the upper end surface of the molten metal has reached the vicinity of the upper end of the injection sleeve, so injection into the cavity can be started immediately.

〔Example〕

Fig. 1 is a schematic vertical cross-sectional view of a vertical casting die-casting machine and its hydraulic circuit diagram, which are shown to explain the method of joining an injection sleeve to a mold according to the present invention, and Fig. 2 is a vertical cross-sectional view of a flow rate control valve. It is a diagram. In the figure, a die casting machine 1 includes a fixed mold 2 mounted on a fixed platen, and a movable mold 3 mounted on a movable platen which is lowered and clamped by a mold clamping device (not shown). By joining the mold 3 to the stationary mold 2 and clamping the mold, a cavity 4 is formed at the joint between the two molds 2 and 3. A sleeve hole 5 is provided directly below the cavity 4. On the other hand, an injection device, generally designated by reference numeral 6, is supported vertically and tiltably about a shaft 7 on a support frame that is suspended from the machine base that supports the fixed platen into a pit below the floor surface. . The injection device 6 includes an injection cylinder 8 having a substrate 8a pivotally supported on a shaft 7.
A plunger 10 having a plunger tip 10a is connected via a coupling 11 to a piston rod 9 that moves forward and backward within the cylinder 8b of the injection cylinder 8 by oil supply from a hydraulic circuit, which will be described later. Reference numeral 12 designates a block formed in the shape of a hollow cone, and a piston rod 9 is engaged in a hole provided in the bottom plate of the block. A ram 14 implanted in 8a is fitted. An injection sleeve 15 is fitted into the upper end of the inner hole of the block 12. By standing the injection device 6 upright and supplying oil to the cylinder 13, the block 12 is raised and the injection sleeve 15 is inserted into the sleeve hole 5. The mold 2 and the injection sleeve 15 are connected to each other. Reference numeral 16 denotes molten metal that is supplied into the injection sleeve 15 while the injection device 6 is tilted as shown by the chain line in the figure.

17 is a solenoid valve whose A port and B port are connected to the head end side and rod end side of the injection cylinder 8 through pipes 18 and 19, respectively, and is equipped with solenoids 17a and 17b, and inside the pipe 18, A flow control valve 20 is provided whose opening degree can be changed as appropriate based on an external electrical command. Further, 21 is a solenoid valve whose A port is connected to the cylinder 13 of the block 12 through the inside of the ram 14 by a pipe 22, and whose B port is blocked, and is equipped with solenoids 21a and 21b.
A flow control valve 23 is provided in the pipe 22, and the opening degree can be kept constant manually by an operator, or the opening degree can be changed to a predetermined amount by an external electrical command. 24 is a hydraulic pump connected to the P ports of the electromagnetic valves 17 and 21 via piping, and 25 is a tank connected to the T ports of the electromagnetic valves 17 and 21.

Here, the structure of the flow control valves 20 and 23 will be explained based on FIG. 2, taking the flow control valve 20 on the injection cylinder 8 side as an example. The casing of the flow rate control valve 20 is formed into a concentric integral body consisting of a cylindrical casing 26 with a bottom, a motor stand 27 joined to the open end side of the casing 26, and a valve body 28 as a valve main body joined to the bottom side. A pulse motor 29 that rotates by an amount corresponding to the number of command pulses in response to an external electrical command is mounted on the motor stand 27, and the motor shaft 30 is inserted into the hollow part of the motor stand 27. It is prominent. The ball screw, which is generally designated by the reference numeral 31, is a screw mechanism that converts the rotation of a motor shaft 30 into an axial movement, and is equipped with a screw shaft 32 that is pivotally supported on a motor base 27. The shaft 32 and the motor shaft 30 are connected by a coupling 33. The ball screw 31 includes a bottomed cylindrical nut 35 that is screwed into the threaded portion of a screw shaft 32 facing into the inner hole of the casing 26 via a ball 34, and the screw shaft 32 is rotated in the forward direction and the reverse direction. The nut 35 is configured to move backward toward the valve body 28 or move forward toward the motor 29 by rotating the nut 35 toward the valve body 28 or toward the motor 29. 36
is a permanent magnet attached to the circumferential surface of the nut 35, 37
38 is fixed to the casing 26 side, and is equipped with a proximity switch that is sensitive to the movement of the permanent magnet 36, and accurately detects the movement distance in the axial direction of the nut 35 and the spool 40, which will be described later, and provides feedback to the control device. This key fits into the key groove of the nut 35 and restricts rotation of the nut 35.

A cylindrical sleeve 39 is attached to the valve body 28.
The sleeve 39 is fitted with a spool 40 that is fixed to the nut 35 and moves forward and backward integrally therewith. The spool 40 is connected to a drive rod 41 which is fixed to the nut 35 and slidably supported by the casing 26.
and a spool body 42 formed in a cylindrical shape and slidably supported by the sleeve 39 are integrally formed in a concentric manner. Inside the hole, a front chamber 43 and a rear chamber 44 are separated by a spool body 42. Reference numeral 45 denotes a communication passage that passes through the spool body 42 in the axial direction so as to communicate the front chamber 43 and the rear chamber 44, and each communication passage 45
A central portion of the spool body 42 is communicated with an annular passage 46 that opens to the circumferential surface of the spool body 42 . on the other hand,
An annular groove 47 is provided on the inner circumferential surface of the valve body 28, and the sleeve 39 is provided with an annular groove 47 formed in an annular shape over the entire circumference. An annular flow path 48 that communicates the front chamber 43 and the annular groove 47, and an annular flow path 49 that communicates the passage 46 and the annular groove 47 are provided in the front and rear. The front chamber 43 is connected to the solenoid valve 17 by a pipe 18, and the pipe 18 connected to an outflow passage 50 opening to the outside from an annular groove 47 of the valve body 28 is connected to the head end side of the injection cylinder 8. It is connected to the.

With this configuration, when the solenoid valve 20 opens, pressure oil is guided to the front chamber 43, and at the same time, the motor 29 rotates and the spool 40 moves forward in the opening direction, so that the front chamber 43 and the annular flow path are 48 begin to correspond, and passage 46 and annular channel 48 begin to correspond. Therefore, the pressure oil in the front chamber 43 flows through the annular flow path 4.
8 into the annular groove 47, and at the same time flows into the annular groove 47 through the communication passage 45 and the passage 46. Note that the communication passage 4 between the passage 46 and the rear chamber 44
5, no flow occurs. The pressure oil that has merged within the annular groove 47 is discharged from the outflow path 50 and is press-fitted into the injection cylinder 8 .

A part of the block 12 has a pair of upper and lower limit switches 51 that emit a signal when the coupling 11 that also serves as a striker comes into contact with them.
A limit switch 52 is provided, and the position of the limit switch 52 is set so as to limit the retraction limit of the plunger tip 10a with respect to the injection sleeve 15. Also, limit switch 51
is positioned so as to restrict the upper limit of the rise of the plunger tip 10a relative to the injection sleeve 15 at or before the injection sleeve 15 is coupled. 53 is a limit switch that operates when the injection sleeve 15 is connected to the mold sleeve hole 5, and 54 is a limit switch for lowering the injection sleeve 15.

A method for joining the injection sleeve in the die-casting machine configured as described above will be explained. Prior to work, the opening degree of the flow control valve 23 is set so that when the solenoid 21a is energized and the solenoid valve 21 is opened, the rising speed of the block 12 becomes the desired speed. When the valve 17 opens, the plunger tip 10a
The opening degree of the flow control valve 20 is set so that the forward speed of the flow rate control valve 20 changes at a desired speed. In this case, the opening degree of the flow rate regulating valve 20 is controlled until the block 12 is connected to the sleeve hole 5 and until the plunger tip 10a reaches the upper limit position regulated within the injection sleeve 15, that is, Until both the limit switches 51 and 53 act, the forward speed of the plunger tip 10a will be limited to the injection sleeve 15.
The opening degree of the flow control valve 20 is set so that it is considerably faster than the charging speed. Furthermore, before the limit switch 53 acts and the connection of the injection sleeve 15 is completed, after the limit switch 51 acts, the flow control valve is set so that the forward speed of the plunger tip 10a is the same as the charging speed of the injection sleeve 15. Set the opening degree of 23. Furthermore, during injection after the injection sleeve 15 is coupled, the opening degree of the flow control valve 23 is set so that the forward speed of the plunger tip 10a changes at a desired speed or remains at a desired constant speed.

Then, the injection device 6 is operated by a tilting cylinder (not shown).
The entire body is tilted around the shaft 7 to the position indicated by the chain line in the figure, and the plunger tip 10a is kept in a lower position within the injection sleeve 15. A desired amount of molten metal 16 is injected into the injection sleeve 15 using a ladle or the like (not shown). After supplying it, stand it upright to the solid line position. Note that when the inner diameter of the injection sleeve 15 is d, the upper surface of the molten metal 16 should be located approximately 0.8 to 1.3 d below the upper end surface of the injection sleeve 15, including the purpose of preventing hot water from spilling during tilting. It is normal to set the amount of hot water to be supplied. Further, when the limit switch 51 is activated, the upper surface of the molten metal 16 in the injection sleeve 15 is
The injection sleeve 15 is positioned approximately 10 mm below the upper end surface of the injection sleeve 15, for example.

Therefore, while starting the hydraulic pump 24,
When oil is sent to the cylinder 13 of the block 12 via the solenoid valve 21, flow control valve 23 and piping 22,
The block 12 starts to rise at a predetermined speed, and the plunger 10 starts to rise together with the block 12 as the bottom plate of the block 12 contacts the coupling 11. Immediately after the start of ascent, when the solenoid 17a is energized, the pressure oil from the hydraulic pump 24 flows through the solenoid valve 17, the flow control valve 20, and the piping 1.
8 to the head end of the injection cylinder 8. At this time, the opening degree of the flow control valve 20 is set so that the rising speed of the plunger tip 10a is greater than the rising speed of the block 12 and the injection sleeve 15.
a moves forward at a speed faster than the charging speed of the injection sleeve 15 and pushes up the molten metal 16. As the injection sleeve 15 continues to rise and the plunger tip 10a continues to move forward, the upper end of the injection sleeve 15 reaches the entrance of the sleeve hole 5, and when the limit switch 51 is activated, the forward speed of the plunger tip 10a changes as the injection sleeve 15 is inserted. It continues to move forward by being decelerated to the same speed. When the injection sleeve 15 is completely inserted, the plunger tip 10a
is rising as shown by the chain line 10a in the figure, and the molten metal 16 has reached near the cavity 4, so
Injection of the molten metal 16 into the cavity 4 can be started immediately, and the injection cycle is shortened. Of course, the rising speed of the plunger tip 10a at the time of coupling the injection sleeve 15 may be set so that both limit switches 51 and 53 act in almost the same way, or the rising speed of the plunger tip 10a may be set so that the limit switches 51 and 53 act almost in the same way, or the rising speed may be set while smoothly accelerating the rising speed. Alternatively, the speed can be appropriately reduced to match the rising speed of the injection sleeve 15. After injection, after opening the mold and taking out all the cast products from the molds 2 and 3, the pressure oil in the cylinder 13 is drained, the pressure oil is supplied to the rod end side of the injection cylinder 8, and the block 12 is released together with the plunger tip 10a. Also, the injection sleeve 15 is lowered.

Note that the detection device may be controlled using a magnetic scale or the like instead of the limit matches 51 to 54 using pulse signals.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, as a method for joining an injection sleeve to a mold, the plunger tip is moved at a higher speed than the rising speed of the vertical injection sleeve that rises after being supplied with molten metal. The molten metal is pushed up to the extent that the molten metal does not overflow from the upper end of the injection sleeve, and when the injection sleeve starts charging, the forward speed of the plunger tip is reduced to approximately the same speed as the charging speed of the injection sleeve, and the injection sleeve By positioning the upper end surface of the molten metal in the injection sleeve near the upper end of the injection sleeve when the connection to the mold sleeve hole is completed, injection of molten metal into the cavity begins immediately after the injection sleeve is fully inserted. As a result, the injection cycle is shortened and productivity is improved, and the temperature drop of the molten metal is reduced, which improves the flow of the molten metal within the cavity and improves the quality of the molded product.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a vertical casting die-casting machine and its hydraulic circuit diagram, which are shown to explain the method of coupling an injection sleeve to a mold in a vertical casting injection molding apparatus according to the present invention, and FIG. 1 is a longitudinal cross-sectional view of the flow control valve. 2...Fixed mold, 5...Sleeve hole, 10a...
... Plunger tip, 15 ... Injection sleeve, 1
6... Molten metal, 17, 21... Solenoid valve, 20, 23
...Flow control valve, 51, 52, 53, 54...Limit switch.

Claims (1)

[Claims] 1. While the vertical injection sleeve is rising to charge the mold sleeve hole after the molten metal is supplied,
The plunger tip is advanced at a speed faster than this rising speed to push up the molten metal within a range that does not overflow from the upper end of the injection sleeve, and when the injection sleeve starts charging, the forward speed of the plunger tip is set to the charging speed of the injection sleeve. decelerate to approximately the same speed as
In a vertical casting injection molding apparatus, the upper end surface of the molten metal in the injection sleeve is positioned near the upper end of the injection sleeve when the injection sleeve is finished joining to the mold sleeve hole. Injection sleeve joining method.