JP6774997B2 - Injection molding machine - Google Patents

Description

The present invention relates to an injection molding machine.

The injection molding machine can shorten the injection time and improve the product quality by increasing the injection speed. On the other hand, if the injection speed is increased, the gas in the cavity of the mold may not escape and be trapped in the mold, and the heat generated by adiabatic compression may cause molding defects such as burning of the molded product. is there. Patent Document 1 discloses a conventional injection molding machine that suppresses such molding defects.

In the injection molding machine of Patent Document 1, a pneumatic cylinder is connected to the cavity of the mold through a vacuum drawing flow path, and vacuuming is performed by hydraulically operating a piston in the pneumatic cylinder. As a result, the injection molding machine prevents the gas from being trapped in the cavity during the injection operation, and suppresses molding defects such as burning.

Jikkai Sho 59-179020

In the conventional injection molding machine, after the movable mold is brought into close contact with the fixed mold, the gas in the cavity is evacuated by a pneumatic cylinder, and then the resin material is injected into the cavity. Therefore, when the injection operation is started, the pressure inside the cavity is significantly lower than the atmospheric pressure, so the resin material that has flowed into the cavity through the gate of the mold becomes scattered and diffuses at once. Spot-like unevenness may occur on the surface of the molded product.

Further, in foam molding, it is necessary to increase the air pressure in the cavity in order to prevent bubbles from bursting during the flow of the resin material. However, as the filling of the resin material in the cavity progresses, the inside of the cavity is filled. The space volume may gradually decrease and the air pressure may rise more than necessary. As a result, the smooth flow of the resin material is hindered, and there is a risk that flow marks or the like may be generated on the surface of the molded product.

Therefore, an object of the present invention is to provide an injection molding machine capable of effectively suppressing defects in the surface texture of a molded product.

In order to achieve the above object, the injection molding machine according to the present invention is an injection molding machine that injects a resin material into a cavity of a mold, is connected to the cavity, sucks gas from the cavity, or sucks gas from the cavity or the cavity. A pressure adjusting unit that sends gas into the cavity to adjust the air pressure in the cavity, and a control unit that controls the air pressure adjusting unit so as to adjust the air pressure in the cavity during an injection operation of injecting a resin material into the cavity. If, have a, the control unit is configured to control the pressure adjusting unit so that pressure in the cavity becomes a target pressure determined in accordance with the filling rate of the resin material in the cavity, wherein the control unit From the time when the injection operation is started, the pressure adjusting unit is controlled so that the air pressure in the cavity gradually decreases as the filling rate increases .

According to the present invention, there is an air pressure adjusting unit that is connected to the cavity and sucks gas from the cavity or sends gas into the cavity to adjust the air pressure in the cavity, and in the cavity during an injection operation of injecting a resin material into the cavity. It has a control unit that controls the atmospheric pressure adjusting unit so as to adjust the atmospheric pressure of the above. Since this is done, the air pressure in the cavity can be adjusted during the injection operation, so that the diffusion state and the flow state of the resin material in the cavity can be controlled by adjusting the air pressure in the cavity. Therefore, defects in the surface texture of the molded product can be effectively suppressed.
Further, the control unit controls the air pressure adjusting unit so that the air pressure in the cavity becomes a target air pressure determined according to the filling rate of the resin material in the cavity. By doing so, the inside of the cavity can be adjusted to an appropriate atmospheric pressure according to the filling rate, and defects in the surface texture of the molded product can be more effectively suppressed.
Further, the control unit controls the air pressure adjusting unit so that the air pressure in the cavity gradually decreases as the filling rate increases. By doing so, it is possible to prevent the pressure inside the cavity from becoming significantly lower than the atmospheric pressure at the time when the injection operation is started. As a result, it is possible to prevent the resin material that has flowed into the cavity through the gate of the mold from scattering and diffusing, and it is possible to suppress the occurrence of spot-like unevenness on the surface of the molded product. Further, since the air pressure in the cavity can be kept low until the filling of the resin material in the cavity is completed, it is possible to suppress burning of the resin material in the cavity and poor filling.

In order to achieve the above object, the injection molding machine according to the present invention is an injection molding machine that injects a resin material into a cavity of a mold, is connected to the cavity, sucks gas from the cavity, or sucks gas from the cavity or the cavity. A pressure adjusting unit that sends gas into the cavity to adjust the pressure inside the cavity, and a control unit that controls the pressure adjusting unit so as to adjust the pressure inside the cavity during an injection operation of injecting a resin material into the cavity. The control unit controls the pressure adjusting unit so that the pressure in the cavity becomes a target pressure determined according to the filling rate of the resin material in the cavity, and the control unit controls the pressure adjusting unit. From the time when the injection operation is started to the end of the injection operation, the pressure adjusting unit is controlled so that the pressure in the cavity becomes a constant value.

In the present invention, the atmospheric pressure measuring unit for measuring the atmospheric pressure in the cavity is further provided, and the control unit measures the atmospheric pressure in the cavity based on the atmospheric pressure in the cavity measured by the atmospheric pressure measuring unit. It is preferable to feedback control the atmospheric pressure adjusting unit so as to be. By doing so, the air pressure in the cavity can be adjusted accurately.

In the present invention, the atmospheric pressure adjusting unit has a cylinder portion connected to the cavity, a piston portion housed in the cylinder portion so as to be reciprocally movable, and a driving unit for reciprocating the piston portion. It is preferable to have. By doing so, the pressure in the cavity can be adjusted with a simpler configuration than the configuration in which the vacuum pump is adopted as the atmospheric pressure adjusting unit.
In the present invention, the atmospheric pressure adjusting unit includes a cylinder portion connected to the cavity, a piston portion housed in the cylinder portion so as to be reciprocally movable, and a driving unit for reciprocating the piston portion. It is preferable that the control unit controls the drive unit so as to move the piston unit to a position determined according to the filling rate.

In the present invention, the air pressure measuring unit for measuring the air pressure in the cavity is further provided, and the control unit is in the cavity measured by the air pressure measuring unit during the injection operation of injecting the resin material into the cavity. It is preferable to display the atmospheric pressure. By doing so, the air pressure in the cavity during the injection operation can be easily grasped.

According to the present invention, since the air pressure in the cavity can be adjusted during the injection operation, the state of the resin material in the cavity can be controlled by adjusting the air pressure in the cavity. Therefore, defects in the surface texture of the molded product can be effectively suppressed.

It is sectional drawing of the main part of the injection molding machine which concerns on embodiment of this invention. It is a figure which shows the control part of the injection molding machine of FIG. 1, and each functional part controlled by it. It is a figure explaining the mold closing operation in the injection molding machine of FIG. It is a figure explaining the injection operation in the injection molding machine of FIG. It is a figure explaining the plasticizing operation in the injection molding machine of FIG. It is a figure explaining the product take-out operation in the injection molding machine of FIG. It is a figure explaining the operation which adjusts the air pressure in a cavity during an injection operation in the injection molding machine of FIG.

Hereinafter, the injection molding machine according to the embodiment of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 is a cross-sectional view of a main part of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing a control unit of the injection molding machine of FIG. 1 and each functional unit controlled by the control unit. 3 to 6 are views for explaining the molding operation of the molded product in the injection molding machine of FIG. 1, and show a mold closing operation, an injection operation, a plasticizing operation, and a product taking-out operation in this order. FIG. 7 is a diagram illustrating an operation of adjusting the air pressure in the cavity during the injection operation in the injection molding machine of FIG. FIG. 7A is a graph showing the target atmospheric pressure with respect to the filling rate of the resin material in the cavity. FIG. 7B is a graph showing the injection speed of the screw during the injection operation. FIG. 7C is a graph showing the air pressure in the cavity during the injection operation. In the following description, "front and back" refers to the front end side and the rear end side of the cylinder, and corresponds to the left side and the right side of FIGS. 1, 3 to 6.

The injection molding machine 1 according to the present embodiment injects the resin material J into the cavity C of the mold K having the moving mold K1 and the fixed mold K2 to manufacture the product M which is a molded product.

As shown in FIG. 1, the injection molding machine 1 includes a cylinder 10, a screw 30, an atmospheric pressure adjusting unit 53, and an atmospheric pressure measuring unit 57.

The cylinder 10 has a cylindrical cylinder body 11 and a cylinder tip portion 12 which is an injection nozzle attached to the tip end (left end of FIG. 1) of the cylinder body 11. For example, a heating device 13 including a plurality of band heaters is provided on the outer peripheral surface of the cylinder body 11. The heating device 13 may also be provided at the cylinder tip portion 12. The cylinder tip portion 12 is formed with a resin flow path 14 connected to the space inside the cylinder body 11. The injection port 17, which is the outlet of the resin flow path 14, is connected to the runner R formed in the fixed mold K2.

As shown in FIG. 1, the screw 30 has a screw main body 31 and a screw head 32 attached to the tip of the screw main body 31.

The screw body 31 has a cylindrical shape, and a screw flight is provided on the outer peripheral surface. The rear end of the screw body 31 (the end on the right side of FIG. 1, not shown) is connected to a screw drive unit 60, which will be described later.

The screw head 32 includes a head portion 33 having a conical shape (tapered shape), a cylindrical shaft portion 34 coaxially connected to the rear end of the head portion 33, a backflow prevention ring 35 for preventing backflow, and a shaft portion 34. It has a circular sheet 36 provided between the screw body 31 and the screw body 31.

The backflow prevention ring 35 has a cylindrical shape, and is formed so that the outer diameter is substantially the same as the inner diameter of the cylinder body 11 and the inner diameter is larger than the outer diameter of the shaft portion 34. The backflow prevention ring 35 has a shaft portion 34 inserted inside and can move in the front-rear direction with respect to the shaft portion 34.

The backflow prevention ring 35 forms an annular flow path 37 with the shaft portion 34. When the backflow prevention ring 35 moves forward with respect to the shaft portion 34, a gap is formed between the backflow prevention ring 35 and the seat 36. As a result, the resin material J can flow in the annular flow path 37. Further, when the backflow prevention ring 35 moves rearward with respect to the shaft portion 34, it comes into contact with the seat 36 and there is no gap. As a result, the backward flow (backflow) of the resin material J is regulated in the annular flow path 37.

The air pressure adjusting unit 53 is connected to the cavity C through the gas flow path 59, and sucks out a gas containing air or a gas generated by the resin material J from the cavity C or sends the gas into the cavity C to enter the cavity C. Adjust the air pressure P of. The gas flow path 59 is configured so that only gas can pass through.

The pressure adjusting unit 53 includes a tubular cylinder portion 54 connected to the cavity C, a piston portion 55 housed in the cylinder portion 54 so as to be reciprocally movable, and a piston driving unit as a driving unit for reciprocating the piston portion 55. It has 56 and.

The piston portion 55 and the piston drive portion 56 have, for example, a motor and a ball screw mechanism (not shown), and the ball screw mechanism is driven by the motor to reciprocate the piston portion 55 in the cylinder portion 54.

The piston portion 55 divides the internal space of the cylinder portion 54 into two spaces. One space is a pressure adjusting space 54a connected to the cavity C through the gas flow path 59, and the other space is the remaining space 54b open to the outside. The cavity C and the air pressure adjusting space 54a are configured to be airtight. Therefore, when the volume Vk of the air pressure adjusting space 54a increases due to the movement of the piston portion 55, the gas in the cavity C is sucked out into the air pressure adjusting space 54a and the air pressure P in the cavity C becomes low. Further, when the volume Vk of the air pressure adjusting space 54a becomes smaller due to the movement of the piston portion 55, the gas in the air pressure adjusting space 54a is sent to the cavity C and the air pressure P in the cavity C becomes higher. In the present embodiment, the cross-sectional area (cross-sectional area) orthogonal to the axial direction of the internal space of the cylinder portion 54 is 10 cm ² , and the volume V _{0 of the} cavity C is 100 cm ³ .

Since the air pressure adjusting unit 53 can adjust the air pressure P in the cavity C by reciprocating the piston unit 55 in the cylinder unit 54 by the piston driving unit 56, it is simpler than a configuration using a vacuum pump or the like. The configuration is as follows. A vacuum pump may be adopted as the atmospheric pressure adjusting unit 53.

The air pressure measuring unit 57 is a pressure sensor that measures the pressure of gas, and is embedded in the wall portion of the cylinder unit 54 so as to face the air pressure adjusting space 54a of the cylinder unit 54. The atmospheric pressure measuring unit 57 measures the atmospheric pressure in the atmospheric pressure adjusting space 54a, but since the atmospheric pressure adjusting space 54a is connected to the cavity C, the atmospheric pressure measured by the atmospheric pressure measuring unit 57 is the atmospheric pressure in the cavity C. It can be regarded as P. The atmospheric pressure measuring unit 57 may be embedded in the mold K to directly measure the atmospheric pressure P in the cavity C.

Further, as shown in FIG. 2, the injection molding machine 1 includes a screw drive unit 60, a mold clamping drive unit 70, and a control unit 80.

The screw drive unit 60 includes, for example, a motor (not shown), a speed reduction mechanism, a ball screw mechanism, and the like. The screw drive unit 60 rotates and moves the screw 30 forward and backward in the cylinder 10.

The mold clamping drive unit 70 does not show a movable die plate to which the moving mold K1 is attached by bending and stretching the toggle link mechanism of the mold clamping device (not shown) to which the fixing mold K2 is attached. Advance and retreat with respect to the fixed die plate. As a result, the moving mold K1 and the fixed mold K2 are closed and opened.

The control unit 80 controls the operation of the entire injection molding machine 1. The control unit 80 includes, for example, a microcomputer for an embedded device having a CPU, a memory (ROM, RAM, EEPROM), various I / O interfaces, and the like. The control unit 80 is connected to the heating device 13, the piston drive unit 56, the screw drive unit 60, and the mold clamping drive unit 70. The control unit 80 controls each of the above functional units in various operations such as a mold closing operation, an injection operation, a pressure holding operation, a plasticizing operation (weighing operation), a mold opening operation, and a product taking-out operation. Further, the control unit 80 is connected to the atmospheric pressure measuring unit 57, and acquires the atmospheric pressure P in the cavity C based on the signal output from the atmospheric pressure measuring unit 57.

A display operation unit 90 is connected to the control unit 80. The display operation unit 90 includes a display unit 91 for displaying information related to the injection molding machine 1, and an operation unit 92 for inputting an operation. The display unit 91 displays various screens in the display area based on the control signal from the control unit 80. The operation unit 92 includes a plurality of keys, and transmits a signal corresponding to the operation input to each key to the control unit 80. The display operation unit 90 may include a touch panel as the operation unit 92, and may have a software switch configured on the display unit 91 by combining a touch panel superimposed on the display area and an icon displayed therein.

In the present embodiment, the control unit 80 ejects the resin material into the cavity C during the injection operation, and the atmospheric pressure P in the cavity C measured by the atmospheric pressure measuring unit 57 (for example, a numerical value indicating the atmospheric pressure P or FIG. 7 (c). ) Is displayed on the display unit 91.

Next, an example of the operation related to the manufacturing method of the product M, which is a molded product in the injection molding machine 1 of the present embodiment, will be described.

As a preparatory operation, the control unit 80 of the injection molding machine 1 controls the heating device 13 and the screw drive unit 60 to perform a purging operation until the molten resin material J stably flows out of the injection port 17. When the purging operation is completed, the control unit 80 controls the screw drive unit 60 to retract the screw 30 while rotating it, and plasticize (melt) the resin material J to obtain the amount required for one injection. , Supply to the space in front of the screw 30 in the cylinder 10. The cylinder 10 is advanced toward the mold K, and the injection port 17 of the cylinder tip portion 12 is connected to the runner R formed in the fixed mold K2.

When the preparatory operation is completed, the control unit 80 controls the mold clamping drive unit 70 to superimpose the moving mold K1 and the fixed mold K2 and mold-clamp (mold closing operation) as shown in FIG.

At this time, the control unit 80 controls the piston drive unit 56 in parallel with the mold closing operation to move the piston unit 55 to the initial position. In the present embodiment, the initial position of the piston portion 55 is a position where the volume Vk of the atmospheric pressure adjusting space 54a becomes 0 (position L = 0 of the piston portion 55). The volume Vk of the atmospheric pressure adjusting space 54a is proportional to the position L of the piston portion 55. When the piston portion 55 is in the initial position, the air pressure P in the cavity C becomes the initial air pressure P ₀ . In the present embodiment, the initial pressure P ₀ is atmospheric pressure.

Next, the control unit 80 controls the screw drive unit 60 to advance the screw 30 and inject the resin material J into the cavity C of the mold K (injection operation), as shown in FIG.

Further, the control unit 80 controls the piston drive unit 56 in conjunction with the injection operation, and the air pressure P in the cavity C during the injection operation changes according to the filling rate F of the resin material J in the cavity C. The piston portion 55 is moved so as to reach the target atmospheric pressure Pt as shown in a).

The target pressure Pt, as shown in FIG. 7 (a), are set so as to gradually lower the initial pressure P _{0 (atmospheric} pressure) in accordance with filling factor F is increased immediately after the injection operation starts. In addition to this, for example, as in the target pressure Pt'shown in FIG. 7 (a), after the filling rate F becomes high to some extent (for example, 30%), gradually from the atmospheric pressure as the filling rate F increases. It may be set to be low. Alternatively, as shown in FIG. 7A, the target atmospheric pressure Pt ″ may be set so as to have a constant value regardless of the change in the filling rate F. The target atmospheric pressure Pt is appropriately set according to the type of the resin material J, the shape of the cavity C, and the like.

In the injection operation, the screw 30 is advanced at the injection speed S shown in FIG. 7B, and the filling rate F gradually increases as the screw 30 advances. The control unit 80 calculates the injection amount of the resin material J based on the advancing position of the screw 30, and calculates the filling rate F from the injection amount and the volume V _{0 of the} cavity C. Then, the control unit 80 controls the piston drive unit 56 to move the piston unit 55 to the position L of the piston unit 55 calculated based on the target air pressure Pt set in advance according to the filling rate F.

The position L of the piston portion 55 has a proportional relationship with the volume Vk of the atmospheric pressure adjusting space 54a. In the present embodiment, the position L of the piston portion 55 and the volume Vk of the atmospheric pressure adjusting space 54a have the relationship of the following equation (1). However, α is a constant and indicates the cross-sectional area of the internal space of the cylinder portion 54.

According to Boyle's law, the air pressure P in the cavity C, the air pressure in the cavity C immediately before the start of the injection operation (initial pressure P ₀ ), the volume V _{0 of the} cavity C, the volume Vk of the pressure adjustment space 54a, and the injection operation. The volume of the atmospheric pressure adjusting space 54a (initial volume Vk ₀ ) immediately before the start and the filling rate F of the cavity C have the relationship of the following equation (2). The temperature of the gas is considered to be constant.

(1-F) V ₀ of the above formula (2) is the volume of the space portion (the portion not filled with the resin material J) in the cavity C. Then, when the target value (target atmospheric pressure) of the atmospheric pressure P in the cavity C at the filling rate F is Pt, the following equation (3) for obtaining the position L of the piston portion 55 from these equations (1) and (2) is obtained. Derived.

Table 1 shows an example of the filling rate F of the resin material in the cavity C, the target atmospheric pressure Pt set for each filling rate F, and the position L of the piston portion 55 in the embodiment. In the example shown in Table 1, the atmospheric pressure which is the initial pressure P ₀ is 101325 Pa, and the initial volume Vk ₀ of the pressure adjustment space 54a is 0 (the initial position of the piston portion 55 is 0). Further, the volume V _{0 of the} cavity C is set to 100 cm ³ , the cross-sectional area α of the internal space of the cylinder portion 54 is set to 10 cm ^2, and the volume of the gas flow path 59 is ignored. The target atmospheric pressure Pt set for each filling rate F in Table 1 has substantially the same shape as the graph of the target atmospheric pressure Pt shown in FIG. 7A.

The control unit 80 controls the piston drive unit 56 in parallel with the injection operation to move the piston unit 55 to the position L of the piston unit 55 shown in Table 1 above according to the filling rate F. As a result, as shown in FIG. 7C, the air pressure P in the cavity C gradually decreases as the filling rate F increases during the injection operation.

In this way, the control unit 80 controls the piston drive unit 56 so that the air pressure P in the cavity C gradually decreases as the filling rate F increases, so that the inside of the cavity C reaches the time when the injection operation is started. It is possible to prevent the pressure P of the above pressure from becoming significantly lower than the atmospheric pressure. As a result, it is possible to prevent the resin material J that has flowed into the cavity C through the gate of the mold K from scattering and diffusing, and it is possible to prevent spot-like unevenness on the surface of the molded product. Can be suppressed. Further, since the atmospheric pressure P in the cavity C can be kept low until the filling of the resin material J in the cavity C is completed, it is possible to suppress burning and poor filling of the resin material J in the cavity C.

Then, when the filling of the resin material J into the cavity C by the injection operation is completed, the control unit 80 controls the screw drive unit 60 and presses the screw 30 forward to press the resin material J with a predetermined holding pressure. (Pressure holding operation). After the pressure holding operation is completed, the control unit 80 controls the screw drive unit 60 to retract the screw 30 while rotating it, and plasticizes (melts) the resin material J once as shown in FIG. The amount required for injection is supplied to the space in front of the screw 30 in the cylinder 10 (plasticization operation). After that, when the resin material J is cured, as shown in FIG. 6, the control unit 80 controls the mold clamping drive unit 70 to open the moving mold K1 and the fixed mold K2 (mold opening operation), and ejects (not shown). The product M is taken out from the cavity C by the pin (product taking out operation).

After that, the product M is molded by repeating the mold closing operation and the product taking-out operation.

From the above, according to the injection molding machine 1 of the present embodiment, the pressure adjusting unit 53 is connected to the cavity C and sucks out gas from the cavity C or sends gas into the cavity C to adjust the air pressure in the cavity C. The control unit 80 controls the piston drive unit 56 so as to adjust the air pressure P in the cavity C during the injection operation of injecting the resin material J into the cavity C. Since this is done, the air pressure P in the cavity C can be adjusted during the injection operation. Therefore, by adjusting the air pressure P in the cavity C, the diffusion state and the flow state of the resin material J in the cavity C can be adjusted. Can be controlled. Therefore, defects in the surface texture of the product M can be effectively suppressed.

Further, the control unit 80 controls the piston drive unit 56 so that the air pressure P in the cavity C becomes the target air pressure Pt determined according to the filling rate F of the resin material J in the cavity C. By doing so, the inside of the cavity C can be adjusted to an appropriate atmospheric pressure P according to the filling rate F, and the defect in the surface texture of the product M can be more effectively suppressed.

In the above-described embodiment, Boyle's law was used to calculate the position of the piston portion 55, but Boyle-Charles' law was used and the temperature change was considered instead of the above equations (1) to (3). The equation may be derived to calculate the position L of the piston portion 55. By doing so, the air pressure P in the cavity C can be adjusted more accurately.

Further, in the above-described embodiment, the piston portion 55 is moved to a predetermined position L of the piston portion 55 according to the filling rate F, but the present invention is not limited to this. In addition to this, for example, the control unit 80 feedback-controls the piston drive unit 56 so that the air pressure P becomes the target air pressure Pt based on the air pressure P of the cavity C measured by the air pressure measurement unit 57. The piston portion 55 may be moved. Even in a configuration that employs such feedback control, the pressure P in the cavity C can be adjusted accurately.

Further, in the above-described embodiment, the control unit 80 controls the air pressure adjusting unit 53 so that the air pressure P in the cavity C gradually decreases as the filling rate of the cavity C increases. It is not limited to. For example, the control unit 80 adjusts the pressure so as to raise the pressure P in the cavity C to a pressure upper limit value higher than the atmospheric pressure before the injection operation and keep the pressure in the cavity C at the pressure upper limit value during the injection operation. A configuration for controlling the unit 53 may be adopted. By doing so, in foam molding, it is possible to prevent bubbles from bursting during the flow of the resin material, and further prevent the air pressure P in the cavity C from rising more than necessary. be able to. Therefore, the smooth flow of the resin material can be ensured, and the flow marks and the like generated on the surface of the molded product can be suppressed.

Although embodiments of the present invention have been described above, the present invention is not limited to these examples. As long as the gist of the present invention is provided, a person skilled in the art appropriately adding, deleting, or changing the design of the above-described embodiment, or combining the features of the embodiment as appropriate is also present. Included in the scope of the invention.

1 ... Injection molding machine, 10 ... Cylinder, 11 ... Cylinder body, 12 ... Cylinder tip, 13 ... Heating device, 14 ... Resin flow path, 17 ... Injection port, 30 ... Screw, 31 ... Screw body, 32 ... Screw head , 33 ... head part, 34 ... shaft part, 35 ... backflow prevention ring, 36 ... seat, 37 ... annular flow path, 53 ... pressure adjustment part, 54 ... cylinder part, 54a ... pressure adjustment space, 54b ... remaining space, 55 ... Piston unit, 56 ... Piston drive unit, 60 ... Screw drive unit, 70 ... Mold clamping drive unit, 80 ... Control unit, 90 ... Display operation unit, 91 ... Display unit, 92 ... Operation unit, K ... Mold, K1 ... Moving mold, K2 ... Fixed mold, C ... Cavity, R ... Runner, J ... Resin material, M ... Product, F ... Filling rate, L ... Piston position, P ... Pressure in cavity, P ₀ ... Initial pressure, Pt ... Target pressure, V ₀ ... Cavity volume, Vk ... Pressure adjustment space volume

Claims (6)

An injection molding machine that injects a resin material into the cavity of a mold.
An air pressure adjusting unit connected to the cavity and sucking gas out of the cavity or sending gas into the cavity to adjust the air pressure in the cavity.
Possess a control unit which controls the air pressure adjusting unit to adjust the air pressure in the cavity of the resin material during injection operation for injecting said cavity,
The control unit controls the air pressure adjusting unit so that the air pressure in the cavity becomes a target air pressure determined according to the filling rate of the resin material in the cavity.
The control unit is an injection molding machine that controls the air pressure adjusting unit so that the air pressure in the cavity gradually decreases as the filling rate increases from the time when the injection operation is started . An injection molding machine that injects a resin material into the cavity of a mold.
An air pressure adjusting unit connected to the cavity and sucking gas out of the cavity or sending gas into the cavity to adjust the air pressure in the cavity.
It has a control unit that controls the air pressure adjusting unit so as to adjust the air pressure in the cavity during the injection operation of injecting the resin material into the cavity.
The control unit controls the air pressure adjusting unit so that the air pressure in the cavity becomes a target air pressure determined according to the filling rate of the resin material in the cavity.
The control unit is an injection molding machine that controls the air pressure adjusting unit so that the air pressure in the cavity becomes a constant value from the time when the injection operation is started to the end of the injection operation. Further having an atmospheric pressure measuring unit for measuring the atmospheric pressure in the cavity,
Claim 1 or claim 2 that the control unit feedback-controls the air pressure adjusting unit so that the air pressure in the cavity becomes the target air pressure based on the air pressure in the cavity measured by the air pressure measuring unit. The injection molding machine described in. The pressure adjusting unit includes a cylinder portion connected to the cavity, a piston portion housed in the cylinder portion so as to be reciprocally movable, and a driving unit for reciprocating the piston portion. The injection molding machine according to any one of claims 1 to 3 . The atmospheric pressure adjusting unit includes a cylinder portion connected to the cavity, a piston portion housed in the cylinder portion so as to be reciprocally movable, and a driving unit for reciprocating the piston portion.
The injection molding machine according to claim 1 or 2, wherein the control unit controls the drive unit so as to move the piston unit to a position determined according to the filling rate. Further having an atmospheric pressure measuring unit for measuring the atmospheric pressure in the cavity,
One of claims 1 to 5 , wherein the control unit displays the air pressure in the cavity measured by the air pressure measuring unit during an injection operation of injecting a resin material into the cavity. The injection molding machine according to paragraph 1.

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