JPH0588656B2 - - Google Patents

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. It relates to a reaction injection molding machine that molds plastic products through a chemical reaction by feeding the plastic into
This invention relates to a stock solution mixing device for injecting the above 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 stock solution A stored in a first stock solution storage tank 1 and stock solution B stored in a second stock solution storage tank 2 to a mixing head 3, where the mixed stock solution is mixed. A stock solution pressure feeding cylinder 6 is connected to the first stock solution storage tank 1 through a communication pipe 4 and a switching valve 5 provided in the communication pipe 4. , this raw liquid pressure feeding cylinder 6 is equipped with a mixing head 3.
A connecting pipe 7 is connected thereto. The switching valve 5 is used to switch the undiluted solution A between a state of distribution and a state of prevention of flow. In addition, the mixing head 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 mix the stock solutions A and B into the respective first molds. and the second
A spool 8 is provided for returning the stock solution to the stock solution storage tanks 1 and 2, respectively. code 9
is a communication pipe (return flow path) for sending the stock solution A back to the first stock solution storage tank 1, and this communication pipe 9
is provided with a check valve 10 that allows flow only to the first stock solution storage tank 1 side.

Furthermore, since the configuration on the second stock solution storage tank 2 side is also similar to that on the first stock solution storage tank 1 side, 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, the piston of each stock solution pumping cylinder 6 is moved in the backward direction (in the direction of the dashed-dotted line arrow in the figure). , stock solution A or stock solution B is sucked into each stock solution pressure feeding cylinder 6. Then, each switching valve 5 is switched to the closed state, and the piston of each stock solution pressure-feeding cylinder 6 is moved in the forward direction (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. ,
After circulating between the stock solution tanks 1 and 2, the spool 8 is moved in the backward direction (in the direction of the one-dot chain arrow in the figure). Then, each of the stock solutions A and B is discharged from each stock solution pressure feeding cylinder 6 and sent to the mixing head 3.
The stock solution is mixed here and 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.
There is a drawback that it is not possible to mold a product larger than the total capacity of the cylinder.

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 pumping cylinders for stock solution A, for example, and is operated alternately while overlapping the discharge states of these two stock solution pumping cylinders to continuously supply stock solution A to the mixing head. It is something.

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 A 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, so that the same flow rate of raw liquid A as when discharging with one cylinder is delivered to the mixing head. The trend is to encourage an influx of people. Then, when the discharging of one of the raw liquid pressure feeding cylinders that discharged first is completed, the moving direction of the piston of this raw liquid pressure feeding cylinder is reversed, and this time, the raw liquid A is sucked, and this suction operation is also performed on the other raw liquid pressure feeding cylinder. Finish before dispensing is complete. Then, before the discharge of the other stock solution pressure-feeding cylinder is completed, the stock solution A is also discharged from one of the stock solution pressure-feeding cylinders, thereby creating a state in which the stock solution A is simultaneously discharged by the two stock solution 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, the latter stock solution mixing device has the advantage that it is possible to mold a product with a capacity greater than the total capacity of the four stock solution pumping cylinders used for discharging the stock solutions A and B.

[Problem to be solved by the invention] However, in the latter stock solution mixing device,
For example, when changing the number of stock solution pumping cylinders from one to two, the piston of the stock solution injection cylinder that has been discharging stock solution A until now, for example, must be moved so that the flow rate of stock solution A supplied to the mixing head is constant. The speed must be controlled to decrease, and in accordance with the change in the moving speed of this piston, the moving speed of the piston of the other stock solution injection cylinder must also be controlled. 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, there are problems such as the compressibility of each stock solution A and B and the response delay of proportional valves, etc. Each stock solution A injected into the mixing head each time it changes from two bottles or two to one bottle,
It is conceivable that the flow rate of B changes and this causes poor mixing of the stock solution.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to mix and inject a stock solution having a volume greater than the total capacity of each stock solution pumping cylinder into a mold,
Moreover, it is an object of the present invention to provide a stock solution mixing device for a reaction injection molding machine that is inexpensive and free from the risk of poor mixing.

[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 mixing chamber in communication with each of these concentrate pumping cylinders via an injection nozzle and a return port communicating with each concentrate storage tank via a return flow path; In the open state, each injection nozzle is connected to the mixing chamber, and the communication between each injection nozzle and each return port is cut off, and in another position, each injection nozzle is closed, and communication with the mixing chamber is cut off, and each injection nozzle is connected to each return port. and a nozzle opening/closing mechanism in communication with the nozzle opening/closing mechanism, the nozzle opening/closing mechanism 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 then switched to an open state, and a control device is connected to the 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 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 pressure feeding cylinder reaches a predetermined amount, the injection nozzle is closed before all the stock solution is discharged from each stock solution pumping cylinder, and each stock solution is No more injection into the mixing chamber. And again,
After suctioning the stock solution into the stock solution pressure-feeding cylinder, the discharge of the stock solution is repeated as described above. As a result of the above, the raw liquid in an amount equal to or greater than the total capacity of each raw liquid pressure feeding cylinder is mixed and sent into the mold.

Since the stock solutions are mixed after the discharge state of the stock solutions reaches a steady state or a state near the 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
Three single-rod type raw liquid pressure feeding cylinders 6 are connected in parallel via three communication pipes 4.
Each communication pipe 4 is provided with a switching valve 5 . In addition, each stock liquid pressure feeding cylinder 6 has a communication pipe 2.
1 are connected to each other, and these communication pipes 21 are connected to a communication pipe 24 which communicates with an injection nozzle 23 of a mixing head 22. And each of the above communication pipes 2
1 is provided with a switching valve 25 that switches the undiluted solution A between a state of distribution and a state of prevention of flow.

The mixing head 22 has a through hole 2 in its center.
A pair of injection nozzles 23 are provided at the tip of the through hole 26 facing each other so as to face the inside of the through hole 26, and a pair of injection nozzles 23 are provided at the base end side of the injection nozzle 23. A pair of return ports 27 are provided facing each other so as to face the inside of the hole 26. A spool 28 is inserted into the through hole 26 so as to be slidable in the axial direction.

The spool 28 has an injection nozzle 23 and a return port 2 arranged on its outer peripheral surface from near the distal end toward the proximal end.
A groove 28a is formed for communicating with the spool 28, and the base end of the spool 28 is connected to a piston 30 of a hydraulic cylinder 29 for driving the spool. Further, the cross-sectional area of the groove 28a is designed so that the undiluted solution A flowing through the groove 28a receives as little fluid resistance as possible from the undiluted solution A flowing through the injection nozzle 23.

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

And the spool driving hydraulic cylinder 29
and the spool 28 constitute an opening/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 similar to that of the first stock solution storage tank 1 side. Therefore, the configuration of the second stock solution storage tank 2 is similar to that of the first stock solution storage tank 1.
The same reference numerals as the constituent elements on the side will be given and the explanation will be omitted.

In addition, the switching valve 5, the switching valve 25, the spool driving hydraulic cylinder 29, and the hydraulic cylinder 32
is controlled by a control device 33 shown in FIG. However, as described above, since the first stock solution storage tank 1 side and the second stock solution storage tank 2 side are configured similarly, the control device 3
3 will also explain the structure of the first stock solution storage tank 1 side, and will omit the explanation of the structure of the second stock solution storage tank 2 side.

In FIG. 2, reference numeral 34 is a detector that detects the pressure, cylinder speed, cylinder position, etc. of the stock solution A in each stock solution pressure feeding cylinder 6, and the signal of the stock solution A detected by this detector 34 is sent to the control circuit 35. It is starting 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, the spool driving hydraulic cylinder 29 is controlled. This control circuit 35 controls each hydraulic cylinder 32 so that the protrusion amount per unit time of each raw liquid pressure feeding cylinder 6 is the same as the set value, and also controls the discharge starting point of the raw liquid A as shown in FIG. The hydraulic equipment 3 maintains the spool 28 at the forward end position until the preset pressure P is reached.
A hydraulic cylinder 29 for driving the spool is controlled via 6. The set pressure P is set slightly before the state in which the discharge pressure of the stock solution A becomes constant at a predetermined value (steady state). Further, the control circuit 35 is configured such that the discharge pressure of the stock solution A is set to a set pressure P.
When the pressure reaches the set pressure P, the spool driving hydraulic cylinder 29 is controlled via the hydraulic device 36 so as to move the spool 28 to the backward end position, and the time is measured from the time when the set pressure P is reached. When a preset time t is reached, the spool driving hydraulic cylinder 29 is activated via the hydraulic device 36 to move the spool 28 to the forward end position again.
control. The above setting 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. Furthermore, the control circuit 35 sequentially controls one hydraulic cylinder 32 to move the piston of the stock liquid pressure feeding cylinder 6 in the forward direction, thereby discharging the stock solution A, and at the same time discharging the stock solution A from the other hydraulic cylinders 32 that are not discharging the stock solution A. The piston of the stock liquid pressure feeding cylinder 6 also moves sequentially in the backward direction to suck the stock solution A into the stock liquid pressure feeding 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 closed, In addition, at this time, the switching valves 5 and 25 are controlled so that the switching valve 5 corresponding to the raw liquid pressure feeding cylinder 6 sucking the raw liquid A is opened, and the other switching valves 5 are closed. It's becoming like that.

Next, the operation of the stock solution mixing device configured as above will be explained. However, regarding the effect, the first
The components on the side of the stock solution storage tank 1 will be explained, and the explanation on the side of the second stock solution storage tank 2 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 cylinders 6 in which the stock solution 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 stock solution A, the switching valve 25 corresponding to the stock solution pumping cylinder 6 to be discharged is opened, and the other switching valves 25 are closed.
The switching valve 5 corresponding to the raw liquid pressure-feeding cylinder 6 to be discharged is closed, and the piston of the raw liquid pressure-feeding cylinder 6 is driven in the forward direction by the hydraulic cylinder 32. Then, the stock solution A is discharged from this stock solution pressure feeding cylinder 6, and the discharged stock solution A is
The piston of the raw liquid pressure feeding cylinder 6 moves forward while maintaining the set speed, and the communication pipe 21 and the switching valve 2
5, communication pipe 24, injection nozzle 23, spool 28
The liquid flows into the first stock solution storage tank 1 through the groove 28a, the return port 27, the communication pipe 9 and the check valve 10.
Then, depending on the flow rate of the stock solution A, the injection nozzle 23
When the fluid resistance of the undiluted liquid A passing through increases and the discharge pressure of the undiluted liquid A becomes equal to or higher than the set pressure P, the spool 28 is moved in the backward direction by the spool drive hydraulic cylinder 29 from the time when the set pressure P is reached. The injection nozzle 23 is opened to the mixing chamber 31. Then, the raw liquid pressure feeding cylinder 6
The stock solution A discharged from the injection nozzle 23 flows into the mixing chamber 31, and similarly the stock solution B also flows into the mixing chamber 31. As a result, the stock solutions A and B are collidingly mixed in the mixing chamber 31 and sent into the mold. Next, when a set time t has elapsed after reaching the set pressure P, the spool 28 is moved in the forward direction by the spool drive hydraulic cylinder 29, and the injection nozzle 23 is closed to the mixing chamber 31. As the groove 2 of the spool 28 becomes
8a brings the injection nozzle 23 and the return port 27 into electrical continuity. For this reason, the raw liquid pressure feeding cylinder 6
The stock solution A discharged from the injection nozzle 23,
It returns to the first stock solution storage tank 1 through the groove 28a of the spool 28 and the return port 27. When the stock solution A in the stock solution pressure-feeding cylinder 6 reaches a discharge completion point E where it is completely discharged, the drive of the stock solution pressure-feeding cylinder 6 is stopped, and the switching valve 25 corresponding to the stock solution pressure-feeding cylinder 6 is closed. , the switching valve 5 is also switched to the open state. The piston of the raw liquid pressure feeding cylinder 6 is driven in the backward direction by the hydraulic cylinder 32, and the raw liquid A is sucked into the raw liquid force 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. Point E
When this point is reached, the driving of the stock solution pressure feeding cylinder is stopped, and the stock solution A is sucked in the same manner as described above. It is desirable that the suction of this 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 3
The stock solution A is sequentially pumped into the mixing chamber 31 from the stock solution pumping cylinders 6 .

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

Therefore, in the stock solution mixing apparatus configured as described above, the stock solution A is supplied to the mixing chamber 3 in an amount equal to or greater than the total capacity of the three stock solution pressure-feeding cylinders 6.
1 can be pumped. Therefore, there are six stock solution pressure feeding cylinders 6 for pumping stock solution A and stock solution B.
It is possible to mold products that exceed the capacity of . Moreover, since the stock solutions A and B are supplied to the mixing chamber 31 when the discharge flow rates of the stock solutions A and B reach near a 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 until the other raw liquid force feeding cylinders 6 start discharging can be extremely shortened.

In the above embodiment, the three stock solution pressure feeding cylinders 6 are provided for the first stock solution storage tank 1 or the second stock solution storage tank 2, but the first stock solution storage tank 1 or the second stock solution storage tank 2 It may be configured such that one or more stock solution pumping cylinders are provided for two stock solution storage tanks 2. however,
In the case where one stock solution pressure feeding cylinder is provided, 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 becomes long during the stock solution suction. Therefore, by the time the discharge of the concentrate from one of the concentrate cylinders is completed,
It is desirable to provide a plurality of cylinders for pumping the stock solution so that the suction of the stock solution by the other cylinders for pumping the stock solution can be completed.

In addition, although a single-rod type cylinder was used as the raw liquid pressure feeding cylinder 6, a double-rod type cylinder was used, and while the raw liquid was being discharged from one rod side, the raw liquid was being delivered to the other rod side. It may be configured such that when one ejection is completed by suction, the next ejection is performed immediately.

[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. , the mixing chamber is communicated with each of these raw liquid pumping cylinders through an injection nozzle, and the mixing head is connected with a return port through a flow path returning to each raw liquid storage tank, and each injection nozzle is in an open state at one position. At the same time, each injection nozzle is closed at another position to disconnect from the mixing chamber and each injection nozzle is connected to each return port. and a nozzle opening/closing mechanism, wherein the nozzle opening/closing mechanism detects 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 the injection nozzle is switched to an open state, and a control device is connected 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 a closed state, the flow rate is always stable. The stock solution can be discharged into the mixing chamber. 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 the drawing]

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,
FIG. 3 is an explanatory diagram showing the discharge pressure of the stock solution, and FIG. 4 is a schematic configuration diagram of a stock solution mixing apparatus shown as a conventional example. 1... First stock solution storage tank, 2... Second stock solution storage tank, 9... Communication pipe (return flow path), 27
... Return port, 6 ... Raw liquid pressure feeding cylinder, 22 ...
Mixing head, 23... Injection nozzle, 28... Spool, 29... Hydraulic cylinder, 31... Mixing chamber,
33...control device, A...undiluted solution, B...undiluted solution.

Claims (1)

[Claims] 1 A plurality of stock solution storage tanks, a stock solution pressure feeding cylinder that is individually connected to these stock solution storage tanks and sucks and discharges the stock solution from each stock solution storage tank, and a mixing chamber is connected to each of these stock solution pressure delivery cylinders via an injection nozzle. A mixing head with a return port in communication with each stock solution storage tank via a return flow path, and a mixing head with a return port in communication with each stock solution storage tank via a return flow path, and a mixing chamber with each injection nozzle in an open state in one position and a connection between each injection nozzle and each return port. and a nozzle opening/closing mechanism for closing each injection nozzle at another position to cut off communication with the mixing chamber and communicating each injection nozzle to each return port, the nozzle opening/closing mechanism including: The injection nozzle is switched to an open state upon 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, and the stock solution is 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 is connected to detect that a predetermined amount has been discharged and switch the injection nozzle to a closed state.