JPH02249615A - Raw liquid mixing device for reaction injection molding machine - Google Patents

Abstract

PURPOSE:To form a raw liquid device of a reaction injection molding machine not to generate any defective mixing by providing a mixing head with a mixing chamber communicated with respective raw-liquid compressively transferring cylinders through an injection nozzle and a nozzle opening and closing mechanism provided in said mixing head and opening and closing said injection nozzle to the mixing chamber. CONSTITUTION:When liquid plastic raw liquid A is to be discharged, an on-off valve 25 corresponding to a raw liquid compressively transferring cylinder 6 is made open while other on-off valves 25 are made closed, and on-off valves 5 to the raw liquid compressively transferring cylinders 6 are made closed, and pistons of the raw liquid compressively transferring cylinders 6 are driven forward by hydraulic cylinders 32. The raw liquid A discharged out of the raw liquid compressively transferring cylinders 6 passes through communicating tubes 21, on-off valves 25, an injection nozzle 23, channels 28a of a spool 28 and check valves 10 and flows into a raw liquid storage tank 1. When the pressure of the raw liquid A becomes discharge pressure P or higher, the injection nozzle 23 is made open to a mixing chamber 31, and the discharged raw liquid A flows into the mixing chamber 31 through the injection nozzle 23. Similarly, raw liquid B flows into the mixing chamber 31, and the raw liquids A and B collide with to be mixed and fed into the mold.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves injecting a plurality of liquid plastic raw materials (hereinafter referred to as stock solutions) into a mixing head, colliding and mixing them at high pressure, and applying the mixed stock solution to a mold. The present invention relates to a reaction injection molding machine that molds plastic products through a chemical reaction by feeding the stock solution into a mixing head, and particularly to a stock solution mixing device for injecting the stock solution into a mixing head and mixing it.

[Prior Art] Conventionally, as a stock solution mixing device for this type of reaction injection molding machine, one shown in FIG. 4 is known.

That is, this stock solution mixing device pumps the stock solution stored in the first stock solution storage tank 1 and the stock solution 1ffl B stored in the second stock solution storage tank 2 to the mixing head 3, where they are mixed. The stock solution is sent to a mold (not shown), and a stock solution pressure-feeding cylinder 6 is connected to the first stock solution storage tank 1 via a communication pipe 4 and a switching valve 5 provided in the communication pipe 4. A connecting pipe 7 that communicates with the mixing chamber 3 is connected to the raw liquid pressure feeding cylinder 6. The switching valve 5 is used to switch between flowing and blocking the flow of the stock solution. In addition, the mixing nozzle 3 may be configured to mix the stock solutions A and B injected into the mixing head 3 and send the mixture into the mold, or to prevent the mixing and transfer each stock solution A and B again into the sixth tank. A spool 8 is provided for returning to the first and second stock solution storage tanks 1.2, respectively. Reference numeral 9 is a communication pipe for sending the stock solution back to the first stock solution storage tank 1, and this communication pipe 9 is provided with a check valve 10 that only allows flow to the first stock solution storage tank 1 side. It is provided.

Furthermore, since the configuration on the side of the second stock solution storage tank 2 is also the same as that on the side of the first stock solution storage tank 1, the same components are given the same reference numerals and explanations will be omitted.

In the stock solution mixing device configured as described above, after each switching valve 5 is switched to the open state, each stock solution pressure feeding cylinder 6
By moving the piston in the backward direction (in the direction of the dotted chain arrow in the figure), the stock solution A or the stock solution B is sucked into each stock solution pumping cylinder 6. Then, each switching valve 5 is switched to the open state, and the piston of each stock solution pressure-feeding cylinder 6 is moved forward (in the direction of the solid line arrow in the figure), so that each stock solution A and B is transferred to each stock solution pressure-feeding cylinder 6 and mixing head 3. , and the stock solution tanks 1 and 2, the spool 8 is moved in the backward direction (in the direction of the dotted chain arrow in the figure). Then, the stock solutions A and B are discharged from each stock solution pressure feeding cylinder 6 and injected into the mixing head 3, where the mixed stock solutions are sent into the mold.

However, in the above-mentioned stock solution mixing device, the volume of the stock solution injected into the mold is determined by the total volume of each stock solution pumping cylinder 6, and therefore it is not possible to mold a product larger than the total volume of the cylinders. The drawback is that it cannot be done.

Therefore, in order to compensate for the above-mentioned drawbacks, a stock solution mixing device (not shown) has been developed, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-284708.

This stock solution mixing device is equipped with two stock solution pressure-feeding cylinders for stock solution A, for example, and operates alternately while controlling the discharge state of these two stock solution pressure-feeding cylinders, thereby continuously supplying stock solution A to the mixing head. supply.

That is, in this stock solution injection device, while one of the two stock solution pressure-feeding cylinders is discharging the stock solution A, the stock solution is sucked into the other stock solution pressure-feeding cylinder, and this suction is performed as described above. Finishing the discharge earlier than the discharge of one of the raw liquid pressure feeding cylinders. Then, before the discharge of the one stock solution pressure feeding cylinder is completed, the stock solution A is also discharged from the other stock solution pressure feeding cylinder, thereby creating a state in which the two stock solution pressure feeding cylinders discharge the stock solution A at the same time. However, in this case, the moving speed of the pistons of the two raw liquid pressure-feeding cylinders is reduced to 1/2 of that when discharging with one cylinder, and the same flow rate of raw liquid A as when discharging with one cylinder is mixed. It is designed to flow into the head. Then, when the discharging of one of the raw liquid force feeding cylinders that discharged first is completed, the moving direction of the piston of this raw liquid force feeding cylinder is reversed and this time it sucks raw I & A, and this suction operation is also performed by the other raw liquid force feeding cylinder. Finish before dispensing is completed. Then, before the discharge of the other stock liquid pressure-feeding cylinder is completed, the stock solution is also discharged from one of the stock liquid pressure-feeding cylinders, thereby creating a state in which the stock solution A is simultaneously discharged by the two stock liquid pressure-feeding cylinders.

As described above, the stock solution A is alternately discharged from the two stock solution pressure feeding cylinders, and the stock solution A is continuously injected into the mixing head. Similarly, stock solution B is continuously injected into the mixing head.

Therefore, according to the latter stock solution mixing device, the stock solution A
, B is advantageous in that it is possible to mold a product with a capacity greater than the total capacity of the four raw liquid pumping cylinders used for discharging .

[Problems to be Solved by the Invention] However, in the latter method of mixing the stock solution, for example, when changing from one stock solution pumping cylinder to two, it is difficult to maintain a constant flow rate of the stock solution supplied to the mixing head. Until now, for example, the movement speed of the piston of one stock solution injection cylinder discharging stock solution A was controlled to be lowered, and the movement speed of the piston of the other stock solution injection cylinder was also controlled according to the change in the movement speed of this piston. Must. For this reason, when the piston of each raw liquid pumping cylinder is driven by a hydraulic cylinder, for example, this hydraulic cylinder is controlled in a complicated manner using a servo valve or a proportional valve with a servo function, and the moving speed of the piston of each raw liquid pumping cylinder is needs to be precisely controlled. Therefore, there is a problem in that the control device for controlling the raw liquid pumping cylinder becomes extremely expensive.

Moreover, even if servo valves and proportional valves are installed for precise control,
Because of problems such as the compressibility of each stock solution A and B and the response delay of proportional valves, etc., each time the number of stock solution pumping cylinders changes from one to two or from two to one, the mixing head It is conceivable that the flow rate of each stock solution A1B to be injected changes, resulting in poor mixing of the stock solutions.

The present invention has been made in view of the above circumstances, and is capable of mixing and injecting a stock solution having a volume greater than the total capacity of each stock solution pumping cylinder into a mold, at a low cost, and without the risk of mixing defects. The purpose of the present invention is to provide a stock solution mixing device for a reaction injection molding machine that is free of

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of stock solution storage tanks, and a stock solution storage tank that is individually connected to these stock solution storage tanks and sucks and discharges the stock solution from each stock solution storage tank. A mixing head having a pressure feeding cylinder, a mixing chamber communicated with each of these raw liquid pressure feeding cylinders via an injection nozzle, and a nozzle opening/closing mechanism provided in this mixing head for opening and closing the injection nozzle with respect to the mixing chamber. The nozzle opening/closing mechanism is configured to open the injection nozzle by detecting that the discharge state of the stock solution discharged from the stock solution pressure feeding cylinder to the mixing chamber is close to a steady state from the start of discharge or has reached a steady state. The injection nozzle is connected to a control device that detects that a predetermined amount of the stock solution has been discharged from the stock solution pressure-feeding cylinder and switches the injection nozzle to a closed state.

[Operation] In the present invention, the stock solution is injected from the stock solution storage tank into the stock solution pressure-feeding cylinder using the stock solution pressure-feeding cylinder, and then the stock solution is discharged from the stock solution pressure-feeding cylinder.

In this case, the injection nozzle is kept closed and each stock solution is not injected into the mixing chamber and mixed until the discharge state of the stock solution is close to the steady state or reaches the steady state from the start of discharge, and the stock solution is discharged. When the condition is close to or reaches a steady state, the injection nozzle is opened and each stock solution flows into the mixing chamber, and the stock solution mixed in the mixing chamber is sent into the mold. Next, when the discharge amount of the stock solution discharged from each stock solution pumping cylinder reaches a predetermined amount, the injection nozzle is opened and each stock solution is discharged before all the stock solution is discharged from the stock solution pumping cylinder. The stock solution is not injected into the mixing chamber (the stock solution is not injected into the mixing chamber). Then, after sucking the stock solution into the stock solution pumping cylinder again, the stock solution is discharged as described above. As a result, the stock solution is mixed in an amount equal to or greater than the total capacity of each stock solution pumping cylinder. and then fed into the mold.

Then, the stock solution is mixed after the discharge state of the stock solution reaches a steady state or near a steady state.
The stock solutions are mixed uniformly.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. However, in these figures, the same reference numerals are given to the elements common to those shown in FIG. 4, and the explanation thereof will be simplified.

As shown in FIG. 1, the first stock solution storage tank 1 includes three
Three single-rod type raw liquid pumping cylinders 6 are connected in parallel through communication pipes 4, and each of the communication pipes 4 includes:
A switching valve 5 is provided.

Further, a communication pipe 21 is connected to each raw liquid pressure feeding cylinder 6, and a communication pipe 24 that communicates with an injection nozzle 23 of a mixing head 22 is connected to these communication pipes 21.

Each of the communication pipes 21 is provided with a switching valve 25 that switches the undiluted solution A between a state of flowing and a state of blocking the flow.

The mixing heel 22 has a through hole 26 formed in its center, and the tip of the through hole 26 is connected to the through hole 26.
A pair of injection nozzles 23 are provided facing each other so as to face the inside, and a pair of return ports 27 are provided on the base end side of the injection nozzles 23, facing each other so as to face the inside of the through hole 26.
is provided. A spool 28 is inserted into the through hole 26 so as to be slidable in the axial direction.

The spool 28 has a groove 28a formed on its outer circumferential surface from near the distal end toward the proximal end for communicating the injection nozzle 23 and the return port 27.
A base end portion of the spool drive hydraulic cylinder 29 is connected to a piston 30 of a spool driving hydraulic cylinder 29. Further, the groove 28a is
The cross-sectional area is designed so that the raw liquid A flowing through the injection nozzle 8a receives as little fluid resistance as possible from the raw liquid A flowing through the injection nozzle 23.

Further, the through hole 26 is a portion where the injection nozzle 23 faces, and a portion on the tip side of the spool 28 is a mixing chamber 31 .

The spool driving hydraulic cylinder 29 and the spool 28 constitute an opening and closing mechanism that opens and closes the injection nozzle 23 with respect to the mixing chamber 31. Further, reference numeral 32 in the figure is a hydraulic cylinder that reciprocates the piston of each of the raw liquid pressure feeding cylinders 6.

Although the structure of the first stock solution storage tank 1 side has been described above, the structure of the second stock solution storage tank 2 side is also the same as that of the first stock solution storage tank l side. Therefore, the configuration of the second stock solution storage tank 2 will be designated by the same reference numerals as the components on the first stock solution storage tank 1 side, and the description thereof will be omitted.

Further, the switching valve 5, the switching valve 25, the spool driving hydraulic cylinder 29, and the hydraulic cylinder 32 are controlled by a control device 33 shown in FIG. However, as described above, since the first stock solution storage tank I side and the second stock solution storage tank 2 side are configured in the same way, the control device 33 will also be explained with respect to the configuration of the first stock solution storage tank ■ side. However, a description of the configuration on the second stock solution storage tank 2 side will be omitted.

In FIG. 2, reference numeral 34 is a detector that detects the pressure of the stock solution in each stock solution pressure feeding cylinder 6, cylinder speed, cylinder position, etc., and the signal of the stock solution A detected by this detector 34 is sent to the control circuit 35. It is ready to be sent.

The control circuit 35 receives each signal from each detector 34, controls the opening/closing state of each switching valve 5 and each switching valve 25, and controls the speed of each hydraulic cylinder 32 via a hydraulic device 36. . Furthermore, a spool drive hydraulic cylinder 2
Control 9. This control circuit 35 controls each hydraulic cylinder 32 so that the amount of protrusion per unit time of each stock liquid pumping cylinder 6 becomes the same as the set value, and also starts discharging the stock I&A as shown in FIG. From point S until the preset pressure P is reached, the spool driving hydraulic cylinder 29 is controlled via the hydraulic device 36 so as to hold the spool 28 at the front end position. The set pressure P is set slightly before the state in which the discharge pressure to the stock solution becomes constant at a predetermined value (steady state). Further, the control circuit 35 controls the spool driving hydraulic cylinder 29 via the hydraulic device 36 so as to move the spool 28 to the backward end position when the discharge pressure of the stock solution A reaches the set pressure P. Time is measured from the time when the set pressure P is reached, and when this time reaches a preset set time t, the spool drive hydraulic pressure is applied via the hydraulic device 36 to move the spool 28 to the forward end position again. The cylinder 29 is controlled. The set time t is set to be shorter than the time required for the resin sucked into the raw liquid pressure feeding cylinder 6 to be completely discharged. moreover,
The control circuit 35 sequentially controls one hydraulic cylinder 32 to move the piston of the raw liquid pumping cylinder 6 in the forward direction, thereby discharging the raw liquid A and discharging other raw liquids that are not discharging the raw liquid A. The piston of the cylinder 6 also moves sequentially in the backward direction to suck the stock solution A into the stock solution pumping cylinder. And this control circuit 35
When discharging the stock solution A from one stock solution pressure-feeding cylinder 6, the switching valve 25 corresponding to the stock solution pressure-feeding cylinder 6 that discharges the stock solution A is opened, and the other switching valves 25 are opened.
is closed, and the switching valve 5 corresponding to the raw liquid pressure feeding cylinder 6 that is sucking the raw liquid A at this time is opened,
Each of the switching valves 5.
It is designed to control 25.

Next, the operation of the stock solution mixing device configured as above will be explained. However, regarding the operation, the constituent parts on the first stock solution storage tank 1 side will be explained, and the explanation on the second stock solution storage tank 2 side will be omitted.

First, the control device 33 is turned on, and the stock solution A is stored in at least one stock solution pumping cylinder 6.

Then, the control device 33 starts discharging the stock solution A from the stock solution pumping cylinder 6 in which stock i[A is stored, and thereafter, the stock solution A is sequentially sent to the mixing head 22 from each stock solution pumping cylinder 6.

When discharging the raw MA, the switching valve 25 corresponding to the raw liquid pressure feeding cylinder 6 that is about to be discharged is opened, and the other switching valves 25 are closed, and the switching valve 25 corresponding to the raw liquid force feeding cylinder 6 that is about to be discharged is opened. 6 is closed, and the piston of the raw liquid pumping cylinder 6 is connected to the hydraulic cylinder 3.
2 in the forward direction. Then, the undiluted solution is discharged from the undiluted solution pressure feeding cylinder 6, and the discharged undiluted solution A moves forward while maintaining the set speed of the piston of the undiluted solution pumping cylinder 6, and the communicating pipe 21, the switching valve 25, the communicating pipe 24, It flows into the first stock solution storage tank 1 through the injection nozzle 23, the groove 28a of the spool 28, the return port 27, the communication pipe 9 and the check valve 10.

Then, due to the flow rate of the stock solution A, the fluid resistance of the stock solution A passing through the injection nozzle 23 increases, and when the discharge pressure of the stock solution A becomes equal to or higher than the set pressure P, the spool driving hydraulic pressure is increased from the time when the set pressure P is reached. The spool 28 is moved in the backward direction by the cylinder 29, and the injection nozzle 23 is opened to the mixing chamber 31. Then, the stock solution A discharged from the stock solution pressure feeding cylinder 6 flows into the mixing chamber 31 through the injection nozzle 23, and in the same way, the stock solution B also flows into the mixing chamber 31.
1. As a result, stock solutions A and B are transferred to the mixing chamber 31.
The mixture is mixed by collision and sent into the mold. Next, when a set time has elapsed from the time when the set pressure P is reached, the spool 28 is moved by the spool driving hydraulic cylinder 29.
is moved in the forward direction, and the injection nozzle 23 becomes open to the mixing chamber 3I, and the injection nozzle 23 and the return port 27 are brought into communication by the groove 28a of the spool 28. Therefore, the stock solution A discharged from the stock solution pressure feeding cylinder 6 returns to the first stock solution storage tank 1 through the injection nozzle 23, the groove 28a of the spool 28, and the return port 27. When the raw liquid 1ffl A in the raw liquid pressure feeding cylinder 6 reaches the discharge completion point E where it is completely discharged, the driving of the raw liquid force feeding cylinder 6 is stopped and the switching valve 25 corresponding to the raw liquid force feeding cylinder 6 is closed. state, and the switching valve 5 is switched to the open state. The piston of this raw liquid pressure feeding cylinder 6 is connected to a hydraulic cylinder 32.
, and the stock solution A is sucked into the stock solution pressure-feeding cylinder 6 through the communication pipe 4 . Furthermore, when one stock liquid pressure feeding cylinder 6 reaches the discharge completion point E, the other stock liquid pressure feeding cylinder 6 is driven, and as described above, the stock liquid A is sent to the mixing head 22 and the discharge is completed. When point E is reached, the drive of the stock solution pressure feeding cylinder is stopped, and the stock solution A is sucked in the same manner as above. It is desirable that the suction of the stock solution A be completed before the discharge of the other two stock solution pumping cylinders 6 is completed.

As described above, under the control of the control device 33, the raw material QA is sequentially pressure-fed into the mixing chamber 31 from the three raw liquid pressure-feeding cylinders 6.

Also, the stock solution B is also added to the mixing chamber 31 at the same timing as the stock solution A.
is supplied to

Therefore, in the stock solution mixing device configured as described above, it is possible to force feed the stock solution A into the mixing chamber 31 in an amount greater than or equal to the total capacity of the three stock solution pumping cylinders 6 . Therefore, it is possible to mold a product having a capacity greater than that of the six stock solution pumping cylinders 6 that pump the stock solutions A and B. Moreover, since the stock solutions A and B are supplied to the mixing chamber 3I when the discharge flow rates of the stock solutions A and B reach near the steady state, the stock solutions A and B can always be mixed uniformly. Furthermore, taking stock solution A as an example, since three stock solution pressure feeding cylinders 6 are provided for the first stock solution storage tank 1, while stock solution A is being pumped by one stock solution pressure feeding cylinder 6, , the stock solution A can be sucked into another stock solution pressure-feeding cylinder 6.

Therefore, the idle time ΔT from when one raw liquid pressure feeding cylinder 6 completes discharging to when the other raw liquid force feeding cylinders 6 start discharging can be extremely shortened.

In addition, in the above embodiment, the first stock solution storage tank 1
Alternatively, the second stock solution storage tank 2 is configured to have three stock solution pressure-feeding cylinders 6, but one or more stock solution pressure-feeding cylinders are provided to the first stock solution storage tank l or the second stock solution storage tank 2. It may be configured to include a cylinder. However, when installing one raw liquid pressure-feeding cylinder,
After the discharge of the stock solution is completed, the stock solution must be sucked by the same stock solution pumping cylinder, and the idle time ΔT is required during the stock solution suction.
becomes longer. Therefore, it is desirable to provide a plurality of liquid solution pumping cylinders so that suction of the liquid liquid by the other liquid liquid pumping cylinders is completed before discharge of the liquid liquid from one of the liquid liquid pumping cylinders is completed.

In addition, although a single rod type cylinder was used as the raw liquid pressure feed/cylinder 6, a double rod type cylinder was used.
While the stock solution is being discharged from one rod side, the stock solution may be sucked into the other rod side, so that when one discharge is completed, the next discharge is immediately performed.

[Effects of the Invention] As explained above, according to the present invention, there are provided a plurality of stock solution storage tanks, and a stock solution pressure-feeding cylinder that is individually connected to these stock solution storage tanks and sucks and discharges stock solution from each stock solution storage tank. , a mixing head having a mixing chamber communicated with each of these raw liquid pressure feeding cylinders via an injection nozzle, and a nozzle opening/closing mechanism provided in this mixing head for opening and closing the injection nozzle with respect to the mixing chamber. , the nozzle opening/closing mechanism switches the injection nozzle to an open state when detecting that the discharge state of the stock solution discharged from the stock solution pressure feeding cylinder to the mixing chamber is close to a steady state from the start of discharge or has reached a steady state; Since it is connected to a control device that detects that a predetermined amount of the stock solution has been discharged from the stock solution pumping cylinder and switches the injection nozzle to an open state, the stock solution with a stable flow rate can always be projected into the mixing chamber. I can do it.

Therefore, by repeatedly discharging the stock solution from each stock solution pumping cylinder, it is possible to feed the stock solution into the mold while uniformly mixing the stock solution in a volume greater than the total capacity of each stock solution pumping cylinder. Moreover, the flow rate of the stock solution can be controlled by a flow rate regulating valve, and even if a servo valve, a proportional valve, etc. are used, control becomes easy, and the cost of the control device for mixing the stock solution can be kept low.

[Brief explanation of drawings]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a stock solution mixing device, FIG. 2 is a block diagram showing the configuration of a control device, and FIG. 3 is a diagram showing an embodiment of the present invention. FIG. 4, which is an explanatory diagram showing the discharge pressure of the stock solution, is a schematic configuration diagram of a stock solution mixing device shown as a conventional example. DESCRIPTION OF SYMBOLS 1... First stock solution storage tank, 2... Second stock solution storage tank, 6... Stock solution pressure feeding cylinder, 22... Mixing head, 23. ...Injection nozzle, 28...
... Spool, 29 ... Hydraulic cylinder, 31.
...Mixing chamber, 33...Control device, A...
...Standard solution, B...Standard solution.

Claims (1)

[Claims] A plurality of stock solution storage tanks, stock solution pressure feeding cylinders that are individually connected to these stock solution storage tanks and suck and discharge the stock solution from each stock solution storage tank, and a mixing cylinder that is communicated with each of these stock solution pressure delivery cylinders via an injection nozzle. The mixing head includes a mixing head having a chamber, and a nozzle opening/closing mechanism provided in the mixing head for opening and closing the injection nozzle with respect to the mixing chamber, and the nozzle opening/closing mechanism includes a mechanism for discharging liquid from the raw liquid pressure-feeding cylinder to the mixing chamber. detecting that the discharge state of the stock solution is close to a steady state from the start of discharge or has reached a steady state, switches the injection nozzle to an open state, and detects that a predetermined amount of the stock solution has been discharged from the stock solution pressure-feeding cylinder; A stock solution mixing device for a reaction injection molding machine, characterized in that a control device for switching the injection nozzle to a closed state is connected thereto.