JPH043895B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a brake device for reducing the mold clamping speed in an injection molding machine.

(Prior Art) Conventionally, injection molding machines have attempted to increase the mold clamping speed by stopping the operation of the mold clamping cylinder due to cycle up. However, if the molds collide at high speed, there is a risk that the molds will be damaged, so when the movable mold starts the mold closing operation at high speed and approaches the stationary mold, the speed is switched to low speed. and,
In order to reduce the mold clamping speed, the amount of oil discharged from the hydraulic pressure supply source (the amount of oil supplied into the mold clamping cylinder) is reduced, and a brake device is used that forcibly reduces the speed.

This brake device has two chambers defined by the piston of the mold clamping cylinder, and when oil is supplied to one chamber during mold clamping, the oil contained in the other chamber is discharged. This method uses the fact that the operating speed of the piston slows down by reducing the discharge amount of the mold to slow down the mold clamping speed.

A mold clamping hydraulic circuit using an example of this brake device is shown in FIG. 6, and will be described.

The mold clamping cylinder 1 is divided into a chamber A by a piston 1a and a chamber B into which a piston rod 1b is inserted.

Further, the variable displacement pump 2 has a suction side connected to the tank T, and a discharge side connected to the discharge pipe line 3. The discharge pipe 3 is branched in the middle, and one side is A.
The other is connected to the B chamber via a conduit 4, and the other is connected to the B chamber via a conduit 5.
connected via. Further, a relief valve 7 is provided in the side passage 6 of the discharge pipe 3 to prevent the discharge pressure of the variable displacement pump 2 from exceeding a certain pressure. Cartridge valves 8 and 9 are provided in each of the pipelines 4 and 5, and these valves selectively supply pressure oil from the variable displacement pump 2 to either chamber A or chamber B of the mold clamping cylinder 1. It is. The pipe line 4 between the cartridge valve 8 and the chamber A is branched and a pipe line 10 is provided. A cartridge valve 11 is provided in the conduit 10, and when the cartridge valve 11 is opened, the oil passing through the conduit 4 can be returned to the tank T. In addition, pipe line 5
The exhaust pipe 12 is also branched off, and cartridge valves 13 and 14 as brake devices are provided in parallel to the discharge pipe 12. and,
The oil liquid is returned to the tank T by opening each of the cartridge valves 13 and 14.

On the other hand, a pilot line 15 for controlling the opening and closing of each cartridge valve is connected to the discharge side line 3 of the variable displacement pump 2. The pilot line 15 is branched after the check valve 16 is connected, and one side is connected to a 4-port, 3-position electromagnetic pilot switching valve 17, and the other side is connected to a 4-port, 2-position electromagnetic pilot switching valve 18. . The 4-port, 3-position electromagnetic pilot switching valve 17 includes a pilot line 19 and a cartridge valve 9 for opening and closing the cartridge valve 8 and the cartridge valve 14.
and a pilot line 20 for opening and closing the cartridge valve 11. Further, a pilot line 21 for opening and closing the cartridge valve 13 is connected to the four-port, two-position electromagnetic pilot switching valve 18.

The operation related to the above configuration will be explained.

First, when the 4-port 3-position electromagnetic pilot switching valve 17 is switched to the side from the state shown in FIG.
9 is connected to tank T. Therefore, the pressure oil from the variable displacement pump 2 is supplied to the chamber A of the mold clamping cylinder 1 through the cartridge valve 8, and operates the piston 1a in the mold clamping direction. At this time, the oil on the chamber B side is returned to the tank T through the discharge pipe 12 and the cartridge valves 13 and 14. Next, the limit switch 22 detects that the movable mold (not shown) approaches the stationary mold, reduces the discharge amount of the variable displacement pump 2, and switches the 4-port 2-position electromagnetic pilot switching valve 18 from C to C. Switch to d. By switching the 4-port 2-position electromagnetic pilot and the switching valve 18, pilot pressure is applied to the cartridge valve 13, which closes the valve, and the oil discharged from the chamber B of the mold clamping cylinder 1 is transferred to the tank T through the passage of the cartridge valve 14 only. As a result, the amount of oil discharged from the chamber B of the mold clamping cylinder 1 is reduced, and a braking action is applied to the piston 1a. In this way, the mold clamping speed is switched from high speed to low speed. In the above hydraulic circuit, the two cartridge valves 13 and 14 and the four-port, two-position electromagnetic pilot switching valve 18 constitute a brake device.

In addition, to open the mold, the cartridge valves 8 and 14 are closed by switching the 4-port 3-position electromagnetic pilot switching valve 17 to b, and the cartridge valves 9 and 11 are closed.
is opened, pressure oil is supplied to chamber B of mold clamping cylinder 1, and oil in chamber A is discharged to tank T through pipe line 10.

(Problems to be Solved by the Invention) The brake device having the above configuration has the following problems.

Two cartridge valves 1 as braking device
3 and 14 in parallel, one cartridge valve 1
3 is closed and the discharged oil is transferred to one cartridge valve 14.
The piping is complicated, and two cartridge valves 13 and 14 have to be used, because the piston of the mold clamping cylinder has a braking effect on the discharged amount. The problem was that the cost was becoming high.

The present invention has been made in view of the above problems, and
The purpose is to throttle the discharge pipe with a simple configuration and create a braking action on the mold clamping cylinder during mold clamping.

(Means for solving the problem) As a means to solve the above problems and achieve the purpose, a cylinder part and a chamber communicating with the cylinder part are provided in the valve body, and the cylinder part receives pressure at the tip of the chamber side. A plunger having a bottomed hole with a surface formed thereon is inserted, an adjustment shaft is inserted into the bottomed hole of the plunger, the adjustment shaft is fixed to the valve body so that its insertion length can be adjusted, and the adjustment shaft is fixed to the adjustment shaft. is provided with an axial passage whose tip is open, and an opening that communicates with the passage and opens on the outer peripheral surface of the adjustment shaft, and the opening is formed when the bottom of the plansha is closest to the tip of the adjustment shaft. In some cases, one pilot conduit is provided that is located in the range of the bottomed hole of the plunger and communicates with the cylinder portion on the rear side of the plunger, and the other pilot conduit is provided that communicates with an axial passage provided in the adjustment shaft. A pilot conduit is provided, the plunger is advanced into the chamber by the pilot pressure of the pilot conduit, and when the opening is out of the range of the bottomed hole of the plunger and communicates with the one pilot conduit, By disposing a cartridge valve that defines the opening degree of the chamber in the middle of a discharge pipe connecting the cylinder chamber of the mold clamping cylinder and the tank, the discharge oil flowing through the discharge pipe can be controlled by the chamber of the cartridge valve. It is characterized in that a predetermined discharge resistance is applied to the discharged oil during passage.

(Function) With the above configuration, the discharged oil flowing in the discharge pipe flows inside the chamber on the way. At the start of mold clamping, the piston is actuated by supplying oil into the mold clamping cylinder and discharging it from a discharge pipe provided in the cylinder chamber. When the movable mold approaches the stationary mold, the pilot pressure of the other pilot conduit is applied to the bottom of the plunger through the passage of the adjustment shaft. The plunger slides on the surface of the cylinder portion and the adjustment shaft and enters the chamber. When the plunger enters the chamber, the opening located in the bottomed hole moves out of the range of the bottomed hole and opens into the cylinder portion. When the opening communicates with one of the pilot pipes, the pilot pressure applied to the bottom of the plunger decreases and becomes balanced with the hydraulic pressure inside the chamber that is received by the pressure receiving surface of the plunger, and the plunger stops with it protruding into the chamber. . At this time, the position where the plunger stops within the chamber can be obtained by changing the insertion length of the adjustment shaft attached to the valve body and fixing it again. In this way, when the plunger enters the chamber, it provides a discharge resistance to the discharged oil, and the amount of oil discharged per hour is reduced, making it possible to apply a brake to the movable mold.

Further, by applying the hydraulic pressure of the oil to the pressure receiving surface of the plunger without applying pilot pressure to the bottom of the plunger, the plunger is retracted into the cylinder portion.

(Example) Next, an example of the present invention will be described based on the drawings.
Note that the description of circuits that are the same as the hydraulic circuit shown in FIG. 6 described in the prior art will be omitted, and only the different parts will be described in detail.

As shown in FIG.
4 is replaced by a special cartridge valve 23. 1 and 2 show a first embodiment of the special cartridge valve, which will now be described. A pilot conduit 21 connected to a four-port, two-position electromagnetic pilot switching valve 18 is connected to a port 25 of a special cartridge valve 23 with a throttle 24 inserted therein. Special cartridge valve 23
A chamber 23c and a cylinder portion 23d are formed in the lower valve body 23b.
is interposed between the discharge pipes 12 and connects the discharge pipes 12. Furthermore, an adjustment shaft 26 having a thread 26c at the end is screwed onto the upper valve body 23a while being inserted into the cylinder portion 23d.
It is fixed at 0. The position of the adjustment shaft 26 can be changed in the vertical direction by loosening the nut 30 and rotating the adjustment shaft 26.

Further, an axial passage 26a with an open tip is formed in the adjustment shaft 26, and the port 25 is connected to the passage 26a.
6a through port 26d. A plunger 27 having a bottomed hole 27b is inserted between the outer periphery of the adjustment shaft 26 and the cylinder portion 23d. The tip of the plunger 27 is the pressure receiving surface 2
7c is formed, and the bottom portion 27a of the bottomed hole 27b has a structure on which pilot pressure can easily act.

Furthermore, the adjustment shaft 26 is provided with an opening 26b that communicates with the passage 26a and opens on the outer periphery of the adjustment shaft 26, and the bottom 27a of the plunger 27 is close to the tip of the adjustment shaft 26 in the opening 26b. In this state, it is closed by the plunger 27.

Further, the pilot pipe 19 piped from the other side is communicated with the inside of the cylinder portion 23d on the rear side of the plunger 27 via a port 28 formed in the upper valve body 23a.

Next, the operation of the above configuration will be explained.

When the piston 1a of the mold clamping cylinder 1 operates in the mold clamping direction and the movable mold approaches the stationary mold, the limit switch 22 detects this and reduces the discharge amount of the variable displacement pump 2, and Switch the 2-position pilot switching valve 18 to the empty position. In this way, the oil flows into the pilot pipe 21, passes through the throttle 24 and the port 25, and connects the adjustment shaft 2.
The pilot pressure acts on the bottom 27a of the plunger 27 to lower the plunger 27. Then, as the plunger 27 descends, the opening 26b is removed from the range of the bottomed hole 27b, and the passage 26a and the port 28 are communicated with each other, so that the oil flows through the port 28 and into the pilot conduit 19. The pilot line 19 is connected to the 4-port, 3-position electromagnetic pilot switching valve 17, but at this time, the 4-port, 3-position electromagnetic pilot switching valve 17 is in the position, so the oil in the pilot line 19 is is returned to tank T. Then, the plunger 27 stops at the lowered position as the pressure applied to the bottom 27a decreases and is balanced with the hydraulic pressure applied to the pressure receiving surface 27c, and the tip of the plunger 27 enters the chamber 23c to discharge the discharged oil. Since the resistance is increased, the amount of oil discharged from the chamber B of the mold clamping cylinder 1 is reduced. (See FIG. 2) By reducing the amount of oil discharged in this manner, a braking action is applied to the piston 1a of the mold clamping cylinder 1, thereby reducing the mold clamping speed of the movable mold.

The special cartridge valve according to the first embodiment of the present invention can be used when the pilot pressure is extremely higher than the hydraulic pressure of the oil discharged from chamber B, and the pilot pressure and the discharged oil If the hydraulic pressures are substantially the same, the following second embodiment is used. This second embodiment differs from the first embodiment only in the shape of the plunger. That is, in the plunger 29 of the second embodiment, the diameter φX of the portion 29a that enters the chamber 23c is made smaller than the diameter φY of the adjustment shaft 26. In this way, the plunger 29 due to the pilot pressure
The pressing force to lower the plunger 29 is greater than the pressing force to move the plunger 29 upward due to the hydraulic pressure of the oil discharged from the chamber B. And plunger 29
will always descend when subjected to pilot pressure. Note that other functions are the same as in the first embodiment.

Here, the reason why the throttle 24 is provided in the pilot conduit 21 is that the plungers 27 and 29 are lowered and the port 2 is closed.
This is to prevent the pilot pressure from decreasing when the port 5 communicates with the port 28, and to adjust the operating time (deceleration time) of the plungers 27 and 29.

In this embodiment, by moving the adjustment shaft 26 up and down, the opening 26b of the adjustment shaft 26 can be moved up and down, and the stopping positions of the plungers 27 and 29 can be changed as appropriate. It has a unique effect, such as being able to select arbitrarily. Note that when hydraulic pressure is applied to the discharge pipe line 12 without applying pilot pressure to the bottom portion 27a, the plungers 27 and 29 receive the pressure through the pressure receiving surface 27c, and the plungers 27 and 29 retreat into the cylinder portion 23d. .

(Effects of the Invention) In the present invention, the plunger in the special cartridge valve is moved by pilot pressure, and the discharge pipe is narrowed to produce a braking action on the mold clamping cylinder, so the circuit is simplified. In addition to reducing costs, the braking force can be easily adjusted by changing the movement range of the plunger using the adjustment shaft, and mold clamping can be performed with a predetermined braking force.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing the operating state of the valve in FIG. 1, and FIG. 3 is a longitudinal sectional view showing a second embodiment of the invention. FIG. 4 is a vertical cross-sectional view showing an example, and FIG. 4 is a vertical cross-sectional view showing the operating state of the valve in FIG. 3. FIG. Figure 6 is
FIG. 2 is a schematic configuration diagram showing a mold clamping hydraulic circuit using a conventional brake device. DESCRIPTION OF SYMBOLS 1... Mold clamping cylinder, 2... Variable displacement pump, 12... Discharge pipe line, 21... Pilot pipe line, 23... Special cartridge valve, 27, 29...
…Pranjiya.

Claims (1)

[Scope of Claims] 1. A cylinder part and a chamber communicating with the cylinder part are provided in the valve body, and a plunger having a bottomed hole with a pressure receiving surface formed at the tip on the chamber side is inserted into the cylinder part, An adjustment shaft is inserted into the bottom hole, and the adjustment shaft is fixed to the valve body so that its insertion length can be adjusted, and the adjustment shaft has an axial passage with an open end and communicates with the passage for adjustment. an opening that opens on the outer circumferential surface of the shaft, the opening being located within the range of the bottomed hole of the plunger when the bottom of the plunger is closest to the tip of the adjustment shaft; One pilot conduit communicating with the inside of the cylinder on the rear side is provided, and the other pilot conduit communicating with the axial passage provided in the adjustment shaft is provided, and the plunger is controlled by the pilot pressure of the pilot conduit. When the cartridge enters the chamber and the opening is out of the range of the bottomed hole of the plunger and communicates with the one pilot pipe, a cartridge valve that defines the opening degree of the chamber is connected to the cylinder of the mold clamping cylinder. By disposing it in the middle of a discharge pipe connecting the chamber and the tank, a predetermined discharge resistance is applied to the discharged oil flowing through the discharge pipe when the discharged oil passes through the chamber of the cartridge valve. A brake device for an injection molding machine characterized by: