JP2590082Y2 - Injection molding equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to an injection molding apparatus,
The present invention relates to an injection molding apparatus capable of preventing the occurrence of defective molded products by verifying the compression characteristics of a compressible molding material such as a rubber material.

[0002]

2. Description of the Related Art Injection molding is performed by injecting a molding material, such as plastics or rubber, which is heated and melted, into a cavity of a mold, and taking out the molded product after cooling. This type of injection molding machine includes a plasticizing device that heats and melts the molding material, an injection device that injects the molding material, a mold clamping device that holds and opens and closes the molding die, and automatically controls the operation of these devices. And a control device for performing the operation.

[0003]

The rubber and plastic materials used as molding materials have compressibility, and the compressibility differs depending on the type (material) of the material and the measurement conditions.

For example, in measuring a material, various conditions such as a screw back pressure, a screw rotation speed, and a preheating temperature of a heating cylinder affect a deaeration effect of the material at this measuring stage. Therefore, the amount of compressible gas such as air and water vapor contained in the material varies depending on these conditions, and the compressibility of the entire material also varies .

[0005] Such a change in the compressibility of the material affects the injection amount. If the injection screw has the same stroke amount but the compressibility is different, the amount of the molding material actually injected will be different. As a result, for example, when the compressibility is high, the injection amount decreases, and insufficient filling occurs. On the contrary, when the compressibility is low, the injection amount increases, and the filling problem (burr leakage) occurs. Had.

However, in the conventional injection molding apparatus,
It was not possible to verify in advance such abnormalities related to compressibility, and after obtaining a molded product, it was actually the case that an abnormality in the molding material was noticed only after performing, for example, an appearance inspection or a functional inspection of the molded product. . Therefore, many defective products are generated, and there has been a demand for the development of an injection molding apparatus capable of verifying an abnormality of a molding material in advance.

[0007] The present invention has been made in view of such problems of the prior art, and it is intended to prevent the occurrence of defective products by verifying the abnormal compressibility of a molding material during injection molding. Aim.

[0008]

In order to achieve the above object, an injection molding apparatus according to the present invention is an injection molding apparatus for moving an injection screw of an extruder in a cylinder and injecting a molten molding material. A first sensor that detects that the injection screw has started moving, a second sensor that detects a pressure value of a molding material in the cylinder,
A timer for measuring a time from a movement start time of the injection screw detected by the first sensor to a time when the molding material in the cylinder detected by the second sensor rises to a predetermined pressure; and It is characterized by having control means for judging whether or not the measured time is within a preset allowable range, and calling out a material abnormality to the outside when it is out of the allowable range.

[0009]

With the injection molding apparatus of the present invention, the actual injection molding is performed, and at the same time, the compression characteristics of the molding material are verified, and the quality of the molding material caused by a material abnormality or an abnormality in the measuring process is determined. That is, regular injection molding is performed by pressing a nozzle of an extruder against an injection port of a molding die, supplying a pressure fluid to an injection pressure cylinder of the extruder, and moving an injection screw at a predetermined pressure in a nozzle direction. Do.

At this time, the movement start time of the injection screw is detected by the first sensor, and the time when the molding material in the cylinder reaches a predetermined pressure is detected by the second sensor. The timer measures the time from the movement start time of the injection screw to the pressure rise time of the molding material, and outputs the result to the control means.

When a molding material having compressibility is injection-molded, the material is compressed in the cylinder from the time when the injection screw starts moving until the material is injected from the nozzle. This time depends on the compressibility of the material.

With such an understanding, the control means determines whether or not the time measured by the timer is within a preset allowable range, that is, within a standard time for molding a normal material. to decide. Then, at least when the value is out of the allowable range, the fact is called out to the outside as a material abnormality.

As a result, it is possible to cope with defects in the molding material, such as immediately exchanging the molding material assuming that the molding material of the lot is defective, and to prevent the occurrence of a large number of defective molded products. Can be.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the injection molding apparatus of the present invention will be described in detail with reference to the drawings. However, the embodiments described below are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the following embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

FIG. 1 is a block diagram showing an injection molding apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view and a graph for explaining the compressibility of a molding material in an extruder of the embodiment.
5 is a flowchart illustrating a processing procedure in a control unit according to the embodiment.

The injection molding apparatus of this embodiment is a molding die, a mold clamping device for opening and closing the molding die, and an extruder 3 for injecting a molding material into the molding die. A hydraulic device 6 for controlling hydraulic pressure and oil flow, plasticizing devices 11 and 12 for plasticizing a molding material, and
And a control device for automatically controlling the operation of each of these devices. Since the mold, the mold clamping device, the plasticizing device, and the control device in the present invention have no problem in the conventionally known configuration, detailed drawings thereof are omitted, and only the outline of the configuration will be described.

The molding die comprises an upper die and a lower die, and a cavity is formed inside by combining these upper and lower dies. The upper die and the lower die are mounted on a die plate via a heating plate and a heat insulating plate, respectively, and one of the die plates is configured to be able to move toward and away from another die plate. In addition, in order to make the tip of the nozzle 4 of the extruder 3 contact the injection port formed in the upper mold,
The heating plate, the heat insulation plate, and the die plate are formed with through holes for passing the nozzle 4.

The upper and lower die plates are provided so as to be able to move close to and away from each other, and the die is fixed so that the die fixed to the die plate is not pushed open by injection pressure. And is constituted by, for example, a mold clamping cylinder or the like.

The extruder 3 is a device for injecting a molding material from a nozzle 4 into a cavity formed between an upper die and a lower die. An injection screw 8 is inserted therein so as to be movable in the axial direction. And a heating cylinder 11. The heating cylinder 11 is provided with a flow path 12 for flowing a heating medium whose temperature has been adjusted. The molding material introduced into the heating cylinder is heated by the rotation of the injection screw 8 to plasticize the molding material. It constitutes a plasticizing device that maintains the state.

On the other hand, the injection screw 8 moves in the heating cylinder 11 by moving the injection pressure cylinder 7 forward and backward while being rotated by a screw drive hydraulic motor (not shown). The hydraulic device 6 for driving the injection pressure cylinder 7 includes, for example, a variable displacement pump, a direction switching valve for switching the pressure feeding direction of the pressure fluid fed from the variable displacement pump, and a pressure of the pressure fluid at a predetermined pressure. And an electromagnetic relief valve for maintaining the pressure.

A pressure fluid is sent from the hydraulic device 6 to the front and rear of the piston 22 of the injection cylinder 7 via a direction switching valve, thereby driving the injection screw 8 up and down in the axial direction. An electromagnetic relief valve is mounted between the hydraulic device 6 and the direction switching valve, and the pressure transmitted from the hydraulic device 6 based on a signal from the injection control device (via a D / A converter or the like). The pressure of the fluid is adjusted.

In FIG. 1, reference numeral 15 denotes a position sensor, which detects the position of the injection screw 8 in the axial direction and outputs it to the position monitor 1. The position monitor 1 detects the start of the movement of the injection screw 8 at the start of the injection molding and outputs a signal for operating the timer 5. The position sensor 15 and the position monitoring unit 1 constitute the first sensor of the present invention. The first sensor of the present invention only needs to be able to detect the start of the movement of the injection screw. Instead of 15, a speed sensor or an acceleration sensor may be provided.

The heating cylinder 11 of the extruder 3 is provided with a pressure sensor 9 for detecting the pressure of the molding material in the heating cylinder 11 and outputting this information to the pressure monitoring unit 2. The pressure monitoring unit 2 detects the rising point of the pressure of the molding material detected by the pressure sensor 9 and
Output a signal to stop the operation. The pressure sensor 9 and the pressure monitoring unit 2 constitute the second sensor of the present invention. The second sensor of the present invention simply needs to be able to detect a certain point in time when the molding material is compressed. For example, a point in time when an arbitrary pressure (for example, 50 MPa) is reached may be detected without detecting a rising point of the molding material.

The timer 5 starts the measurement based on the position information from the position sensor 15, stops the measurement based on the pressure information from the pressure sensor 9, measures the time during the measurement, and outputs it to the comparing unit 16.

The control means 10 according to the present embodiment is provided with an allowable value setting section 14 for inputting and storing in advance a reference time range. For example, the injection molding was performed in a normal state. When the range of time from the start of movement of the injection cylinder to the rise in pressure is T _{MIN to} T _MAX , the minimum value T _MIN and the maximum value T _{MAX of} these times are input.

The comparing section 16 compares the actual time T measured by the timer 5 with the allowable times T _{MIN to} T _MAX stored in the allowable value setting section 14, and the actual time T falls within the allowable time. Is determined. For example, first T
And T _MIN are compared, and if T <T _MIN ,
The state is set to “0”. If T <T _MIN , then
Then compare the magnitude of T and T _MAX, if if T> T _MAX, to the state "2". Finally, if neither “0” nor “2”, the state is set to “1”.

The judging section 21 judges the quality of the molding material based on the result of comparison by the comparing section 16, that is, which of "0", "1" and "2". Specifically, when the actual time T is in the allowable time range T _{MIN to} T _MAX , the result in the comparison unit 16 is “1”. "Or" 2 "is a defective product.

In the display unit 23, the result of the judgment by the judging unit 21 is sent to an operator or the like. Regarding the reminding method, a display panel of a good product and a display panel of a defective product may be provided to notify the user, or only a display panel of the defective product may be provided, and only when the product is defective, the fact may be raised. . further,
The arousing means is not limited to the display, but may be voice or other means. In short, according to the present invention, it is sufficient that at least the molding material is defective.

Next, the operation will be described. First, an allowable time range when a normal molding material is used, specifically, a minimum time T _MIN and a maximum time T _MAX are input to the allowable value setting unit 14 of the control means according to the present embodiment. (Step 1).

Next, the molding material is supplied into the heating cylinder 11 to start injection molding, and at the same time, the position information from the position sensor 15 is taken into the timer 5 (step 2).
When the position monitor 1 detects that the injection screw 8 has started moving based on information from the position sensor 15 (step 3), the timer 5 starts measuring (step 4). At this time, the injection screw 8 and the heating cylinder 1
The molding material in 1 is in a state indicated by "A" in FIG. 2, which is a state before being compressed. This time is referred to as “t ₀ ”.

Before or after this, the pressure information from the pressure sensor 9 is taken into the timer 5 (step 5), and the point in time when the pressure of the molding material in the heating cylinder 11 starts to rise is detected (step 6). Until the molding material in the heating cylinder 11 starts to rise, the injection screw 8 and the molding material in the heating cylinder 11 are in a state indicated by “B” in FIG. This is a state before being ejected from the nozzles.

When the injection screw 8 further moves forward, the pressure of the molding material in the heating cylinder 11 starts to rise, which is detected by the pressure monitoring unit 2 and the timer 5 is stopped (step 7). At this time, the molding material in the injection screw 8 and the heating cylinder 11 is in a state indicated by “C” in FIG. 2 and is in a state in which discharge is started against the fluid resistance of the nozzle. This time is referred to as “t ₁ ”.

The timer 5 calculates and calculates the elapsed time T (= t ₁ -t ₀ ) from the movement start time t ₀ of the injection screw 8 to the pressure rise start time t ₁ in the heating cylinder 11 and compares the results. Output to the unit 16. Next, in the comparing section 16, the actual time T from the timer 5 and the allowable time T _{MIN to} T _MAX stored in the allowable value setting section 14.
To determine whether the actual time T is within the allowable range (step 8).

Specifically, first, the magnitudes of T and T _MIN are compared, and if T <T _MIN , the state is set to “0”. If T <T _MIN , then T and T
The magnitude is compared with _MAX, and if T> _TMAX , the state is set to “2”. Finally, if neither “0” nor “2”, the state is set to “1”.

Then, in the judgment section 21, the comparison section 16
The quality of the molding material is determined based on the comparison result in the above, that is, which of “0”, “1”, and “2”. That is, when the actual time T is within the allowable range T _{MIN to} T _MAX , the result in the comparison unit 16 is “1”. Therefore, when the result is “1”, the result is normal, and “0” or “2” In this case, it is regarded as abnormal (steps 9 and 10).

Finally, an abnormality display signal or the like is output to the display unit 23, and a result of the judgment by the judgment unit 21 is called out to an operator or the like (step 11).

According to the injection molding apparatus of this embodiment, when molding is performed, the compressibility of the molding material is verified and the quality of the molding material of the lot is determined. For example, it is possible to quickly deal with a defect of the molding material, such as changing the molding material, and to prevent the occurrence of a large number of defective molded products.

[0038]

The injection molding apparatus of the present invention measures the time from the movement start time of the injection screw until the molding material in the cylinder rises to a predetermined pressure, and this time is set to a predetermined allowable value. It is configured to judge whether it is within the range or not, and if it is out of the allowable range, it is alerted to the outside as a material abnormality, so the molding material of the lot is determined to be defective and the molding material is immediately It is possible to cope with a defect of the molding material such as replacement, and it is possible to prevent a large number of defective molded products from occurring.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an injection molding apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view and a graph illustrating the compressibility of a molding material in the extruder of the embodiment.

FIG. 3 is a flowchart showing a processing procedure in a control unit according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 position monitoring unit (first sensor) 2 pressure monitoring unit (second sensor) 3 extruder 4 nozzle 5 timer 6 hydraulic device 7 injection pressure cylinder 8 injection screw 9 pressure sensor (Second sensor) 10 control means 11 heating cylinder 12 flow path 14 allowable value setting section (control means) 15 position sensor (first sensor) 16 comparison section (control means) 21 ... determination section (Control Means) 23 Display Unit (Control Means)

Claims (1)

(57) [Scope of request for utility model registration] In an injection molding apparatus for moving an injection screw (8) of an extruder (3) in a cylinder (11) to inject a molding material in a molten state, the injection screw (8) starts moving. A first sensor (15, 1) for detecting the above, a second sensor (9, 2) for detecting a pressure value of the molding material in the cylinder (11), and a first sensor (15, 1). ) From the movement start time of the injection screw (8) until the molding material in the cylinder (11) detected by the second sensor (9, 2) rises to a predetermined pressure (T ), And it is determined whether the time (T) measured by the timer (5) is within a preset allowable range, and if the time (T) is outside the allowable range, Control means (1 0).