JP3395542B2 - Injection molding machine molding condition setting method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection method for efficiently and accurately setting optimum molding conditions for obtaining a predetermined quality when molding a molten resin material using an injection molding machine. The present invention relates to a molding condition setting method for a molding machine.

[0002]

2. Description of the Related Art Conventionally, in injection molding of molten resin,
Set the injection profile in which the horizontal axis is the position of the injection screw and the vertical axis is the forward speed of the injection screw, and the holding pressure profile in which the horizontal axis is time and the vertical axis is the injection pressure. Injection control is performed by the filling process of injecting and filling the molten resin material into the mold cavity with and the pressure-holding process of applying pressure to the resin in the mold cavity after molding the molten resin according to the pressure-holding profile. In the filling process, the pressure adjustment valve of the hydraulic circuit is set to a high pressure, and the opening of the flow control valve is set so that the speed is changed in multiple stages based on the elapsed time from the start of injection or the forward position of the injection screw. It is set so as to change with the passage of time or according to the stroke position of the injection screw, and the flow rate control valve is adjusted to adjust the injection cylinder. Stone, that is, the injection speed of the injection screw is controlled, and the molten resin is filled into the mold cavity at such a high speed that the resin in the mold cavity does not entrap air. After that, the flow control valve is fixed to a relatively small opening and the pressure control valve adjusts the hydraulic pressure to perform a pressure-holding process.This pressure-holding process is performed by the molten resin filled in the mold cavity over time. By changing the opening of the pressure control valve so that a predetermined pressure can be applied to the molten resin, the molten resin is cooled in the mold cavity, and the resin shrinks. It prevents the occurrence of errors and prevents large residual stress inside the product.

In FIG. 6, the molten resin is injected from the screw head front portion 22 of the injection molding machine 20 through the nozzle portion 4 into the mold 10.
The state immediately before injection and filling into the cavity 8 formed by a and 10b is shown. After that, the injection process is started, and the operating oil enters the injection cylinder 16 from the head side 16a of the injection cylinder 16 and the screw 1 Move it forward, nozzle part 4
Then, the molten resin is transferred into the cavity 8. After the cavity 8 is filled with the molten resin, the pressure-holding step is started, and the resin in the front portion 22 of the screw head is pressurized while supplementing the contraction amount due to the cooling and solidification of the resin. What kind of resin inflow velocity pattern and pressure pattern should be used to inject and fill the molten resin in such an injection process and a pressure-holding process, respectively, depends on the quality of the resin molded product molded in the mold. Generally, as described above, for example, in the injection process, as shown in FIG. 7, the screw position and the screw advancing speed are set in relation to each other, and in the pressure holding process, as shown in FIG. In addition, the setting is made in relation to the elapsed time and the holding pressure (oil pressure or resin pressure).

Then, in determining such an injection speed pattern (also referred to as an injection profile) and a pressure pattern (also referred to as a holding pressure profile), an operator can obtain a good product with good reproducibility and stability. In order to understand the above, he has tried to obtain various desired results by trial and error by carrying out various combinations of various molding conditions by making full use of his expert knowledge. In addition to these trial-and-error methods, recently, an attempt is being made to grasp desirable molding conditions with a certain degree of accuracy by a simulation method for in-mold flow analysis of resin making full use of computer technology. Japanese Patent Publication No. 13048/1993, for example, is a conventional technique for obtaining optimum molding conditions by a similar method in patents prior to the present invention.
In the method of this patent, without providing the standard molding conditions,
A large number of molding tests are required because a large number of setting condition factors are set and a large number of change levels are created for the molding test, and the quality judgment of the molded product is 85 out of 100.
The evaluation was complicated by points. Moreover, since a molding condition that maximizes the quality is obtained from multiple molding test results by multiple regression analysis, complicated calculations have to be performed, which is not suitable for practical use.

[0005]

Since the above-mentioned analysis method uses an idealized mathematical formula and resin physical properties for calculation, there is a certain degree of difference between the obtained molding conditions and the optimum molding conditions in actual operation. In some cases, the molded products obtained in actual operation were not always satisfactory. Therefore, some measure to correct the molding conditions obtained by the above-mentioned analysis method to the optimum molding conditions that can obtain a molded product that can be sufficiently satisfied in actual operation, and this measure establishes a quick, simple and easy setting procedure. There was an urgent need for a way to make it. It is an object of the present invention to provide a method for setting optimum molding conditions that can solve such problems and obtain a molded product having a molded product quality that is sufficiently satisfactory in actual operation.

[0006]

In order to solve the above problems, in the present invention, in the first invention, a molten resin material is flow-pressed into a substantially closed mold cavity to form a molded product. A method of setting molding conditions for an injection molding machine that is repeatedly manufactured, in which a mold model that mathematically defines the mold cavity shape is created in advance, and a resin flow analysis is performed when molten resin is flown into the mold model. The optimum molding conditions consisting of the injection profile and the holding pressure profile are calculated, and the allowable upper limit value and the allowable lower limit value of the main molding variables in the molding process are set, and the trial injection molding test is performed based on these optimum molding conditions. At the same time, if the main molding variables during molding deviate from the permissible upper limit value or the permissible lower limit value, a correction program prepared in advance for the optimum molding conditions is used. Correctly repeat the trial casting molding test until it falls within the allowable range, and if the main molding variables during molding fall within the allowable range defined by the allowable upper limit value and the allowable lower limit value, Visually judge the appearance quality, and if there is a defective item, use the above-mentioned correction program or a separately prepared correction program to correct the optimum molding conditions again and repeat the trial casting molding test. In the above, the final molding conditions were set as the optimum molding conditions and the molding conditions in the production process. And in 2nd invention, in 1st invention,
The correction program is a resin flow analysis program having a function of correcting the main molding variables according to the degree of deviation from the permissible range of the main molding variables, and the molding conditions corresponding to the visual quality judgment items visually checked by the operator. The change function of is added.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a molding condition setting method for an injection molding machine in which a molten resin material is flow-pressed into a substantially closed mold cavity to repeatedly produce a molded product. That is, a mold model in which a mold cavity shape is mathematically defined is created in advance, and a resin flow analysis is performed when a molten resin is flown into the mold model to perform optimum molding including an injection profile and a holding pressure profile. In addition to calculating the conditions, setting the upper and lower allowable limits of the main molding variables during the molding process, performing a trial casting test based on this optimum molding condition, If the upper limit value or the lower limit value is exceeded, the optimum molding conditions are corrected using a modification program prepared in advance and tested until it falls within the allowable range. If the main molding variables during molding are repeated within the permissible range defined by the permissible upper limit and the permissible lower limit, the appearance quality is judged visually by the operator and the defective item is found. In some cases, the optimum molding conditions are corrected again using the above-mentioned correction program or a separately prepared correction program, and the trial shot molding test is repeated. If there are no defective items, the final molding conditions are set to the optimum molding conditions. As the molding conditions in the production process. And in 2nd invention, 1st
In the invention, the correction program is a resin flow analysis program having a function of correcting the main molding variable according to the degree of deviation from the permissible range of the main molding variable, and the appearance quality judgment item visually determined by the operator. Since the function to change the molding conditions according to the conditions is added, the molding conditions obtained by the resin flow analysis are evaluated by two checks, a trial casting molding test and the visual quality judgment by the operator's visual observation, to obtain a sufficiently satisfactory quality. By adjusting to the optimum molding conditions that can obtain the prepared molded product and adopting it in the actual operation, it is possible to safely and reliably produce a high-quality molded product in the actual operation.

Further, in the second invention, the correction program is a resin flow analysis program having a function of correcting the main molding variable according to the degree of deviation from the allowable range of the main molding variable, and the operator's program Since a function to change the molding conditions according to the visual appearance quality judgment items is added, the molding conditions are automatically corrected when the items deviate from the allowable range or when the appearance quality judgment results in defective items. Because it is possible to make more improved optimum molding conditions,
It is convenient.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 5 relate to an embodiment of the present invention,
1 is an overall configuration diagram of an injection molding machine, FIG. 2 is a flowchart showing a procedure for setting optimum molding conditions, FIG. 3 is an explanatory view of optimum molding conditions in an injection process, and FIG. 4 is an explanatory view of optimum molding conditions in a pressure holding process. FIG. 5 is a display diagram on the personal computer CRT screen showing an example of the appearance quality judgment table for inputting the appearance quality judgment result.

As shown in FIG. 1, in an injection device 20 of an injection molding machine 100, a screw 1 is inserted into a heating cylinder 3 such that the screw 1 is rotatable and can move forward and backward.
A nozzle 4 is attached to the tip of the. An injection cylinder 16 in which a piston 14 for moving the screw 1 forward and backward is inserted is attached to the rear part, and a screw rotation motor 5 for rotating the screw 1 for rotating the screw 1 is provided behind the injection cylinder 16. A screw motor operating valve 11c for supplying an appropriate amount of pressure oil to the screw rotation motor 5 is provided as a drive source.

The hydraulic chamber of the injection cylinder 16 comprises a head side hydraulic chamber 16a and a rod side hydraulic chamber 16b.
Hydraulic oil is supplied to this hydraulic chamber from a hydraulic pump (not shown) and is controlled by the hydraulic valve 11. The hydraulically operated valve 11 is composed of a head side hydraulically operated valve 11a communicating with the head side hydraulic chamber 16a and a rod side hydraulically operated valve 11b communicating with the rod side hydraulic chamber 16b. Further, in order to measure the injection pressure during the injection process, the head side hydraulic chamber 16a of the injection cylinder 16 is provided with the head side hydraulic pressure sensor 1.
3 is installed.

Reference numeral 8 is a screw position sensor for measuring the forward / backward travel distance of the screw 1, and can also measure the speed. A screw head 18 is screwed onto the tip of the screw 1 with a check sheet 1a placed in the screw head 18. The screw head 18 has a substantially conical shape toward the tip, and the rear side (right side in the figure) of the conical shape is stepped. Becomes a small diameter, and this small diameter part 1
A check ring 2 which is slidable in the axial direction is fitted in 8a.

Near the tip of the nozzle 4 is a mold 1 which is composed of a fixed mold 10a and a movable mold 10b during the injection process.
A nozzle pressure sensor 6a and a nozzle temperature sensor 6c, which measure the resin pressure of the molten resin filled in the mold cavity 8 inside 0, are provided. A mold pressure sensor 6b for measuring the resin pressure in the mold 10 and a mold temperature sensor 6d for measuring the mold temperature are attached to the runner portion 7 connecting the mold cavity 8 and the nozzle 4. There is.

The injection device 20 includes a nozzle pressure sensor 6a arranged in front of the nozzle 4, a resin pressure measurement value, an in-mold pressure sensor 6b measurement value, and an injection cylinder head side oil pressure sensor 13. Injection molding that receives various control commands by receiving the measured value of the hydraulic pressure, the measured value of the hydraulic pressure from the screw motor driving hydraulic pressure sensor 15, or the measured value from another sensor and comparing it with the target value here. A machine controller 30 is provided.

The pressure to be controlled by the present invention means
It means any one of the resin pressure of the nozzle 4 in the injection step, the resin pressure in the mold cavity 8 and the oil pressure of the head side hydraulic chamber 16a of the injection cylinder 16. Since it is considered impossible to control a plurality of pressures simultaneously in one injection process, only one of the nozzle pressure sensor 6a, the in-mold pressure sensor 6b, and the head side oil pressure sensor 13 is selected. It will be good if you wear it. In addition,
Reference numeral 12 is a hopper, 12a is a resin pellet, and 22 is a screw head front portion.

An embodiment of the method for setting the molding conditions of the injection molding machine of the present invention using the injection molding machine 100 thus constructed will be described with reference to the flowchart of FIG.
FIG. 2 is a flowchart showing the procedure for setting the optimum molding conditions. Prior to the actual operation, the optimum molding conditions for analysis are first set. For this optimum molding condition, a mold model that mathematically defines the mold cavity shape is created, and the optimum molding condition for analysis is calculated by making full use of the flow analysis simulation method of resin flow in the mold applying CAE technology. To do. This molding condition is composed of an injection profile of the injection filling process and a pressure holding profile of the pressure holding process.

Next, in the molding process of the injection profile and the holding pressure profile set in this way,
As shown in FIG. 3 and FIG. 4, the allowable lower limit value and the allowable upper limit value (allowable range) such as the injection speed and pressure, which are the main molding variables, and the cushion amount, which is the most advanced position of the screw in the pressure holding process, are set. Make settings. This setting may be done in the flow analysis simulation. The method of the present invention is to find and select the optimum forming condition T in the actual forming from the optimum forming condition S in the analysis by the trial shot forming test and the condition correction, and it is determined by the procedure described below.

Next, a trial injection molding test is executed based on the molding conditions (injection profile and holding pressure profile) and the allowable range described above. In the trial molding test, sensors automatically measure and monitor the main molding variables during molding (injection speed in the filling process, holding pressure in the holding process, cushion amount, etc.), and If the injection speed or the holding pressure in the holding process or the cushion amount deviates from the above allowable range, the test conditions are corrected by the correction program prepared in advance according to the deviation amount, and the trial shot forming test is performed again. Run.

In this way, for shots in which the main molding variables are within the permissible range, the operator visually inspects the appearance of the molded product, and, for example, as shown in FIG. Enter the result in the appearance quality judgment table called on the CRT screen. If there is a defective item equal to or less than the second item in the appearance quality judgment table, the test conditions are corrected by using a correction program prepared in advance, and the trial shot molding test is executed again. If the trial molding test is repeated while performing the above two checking operations, and the main molding variables fall within the initially set allowable range and the appearance quality inspection is also passed, the optimum molding condition T in actual molding is set. Is determined and the actual operation is started under these molding conditions.

As the resin flow analysis program, a commercially available mold flow analysis program "MOLD / FLOW program" can be used. In addition, the correction program usually has a function of correcting the main molding conditions according to the degree of deviation from the allowable range of the main molding variables, and the main molding conditions are corrected according to the defective items of the appearance quality judgment. Two of those having the function to be added are prepared, but these two functions may be added to the resin flow analysis program. Although the present invention is applied to the injection molding machine, it is needless to say that the present invention may be applied to a die casting machine or a squeeze casting machine for molding a metal material.

As described above, in the present invention, a trial shot test is performed based on preset molding conditions, and the molding conditions that have passed as a result of two judgments are determined to be optimum molding conditions, and the actual operation is performed. So that
The molding conditions for hitting good products can be set quickly. According to the results obtained by carrying out the test according to the method of the present invention, the time required for setting the optimum molding conditions was 1/4 of the time required for condition setting by the conventional skilled operator. Further, this setting work procedure is also almost completely automated, and is simple and easy to carry out.

[0022]

As described above, according to the molding condition setting method for the injection molding machine of the present invention, it is possible to quickly and optimally determine the optimum molding conditions in actual molding based on the molding conditions obtained by the resin flow analysis. It can be easily and easily set and does not require the knowledge of a skilled operator.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure for setting optimum molding conditions according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of optimum molding conditions in a filling process according to an example of the present invention.

FIG. 4 is an explanatory diagram of optimum molding conditions in a pressure holding step according to an example of the present invention.

FIG. 5 is a display diagram on a personal computer CRT screen showing an example of an appearance quality judgment table for inputting an appearance quality judgment result according to the embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a conventional injection molding machine.

FIG. 7 is an example of molding conditions in a conventional injection process.

FIG. 8 is an example of molding conditions in a conventional pressure-holding process.

[Explanation of symbols]

1 screw 2 check valves 3 barrels 4 nozzles 5 screw rotation motor 6a Nozzle pressure sensor 6b Mold pressure sensor 6c Nozzle temperature sensor 6d Mold temperature sensor 7 Runner section 8 mold cavity 9 Position sensor 10 mold 10a Fixed mold 10b movable mold 11a Head side hydraulically operated valve 11b Rod side hydraulically operated valve 12 hoppers 12a Resin pellet 13 Injection cylinder head side oil pressure sensor 14 pistons 16 injection cylinder 16a head side chamber 16b Rod side chamber 18 screw heads 18a small diameter part 20 injection device 22 Front of screw head 30 control device 100 injection molding machine L lower limit condition Optimal molding conditions for S analysis Optimal molding conditions for actual molding U upper limit condition

Claims (2)

(57) [Claims] 1. A molding condition setting method for an injection molding machine, wherein a molten resin material is flow-pressed into a substantially closed mold cavity to repeatedly produce a molded product. Create a defined mold model, perform resin flow analysis when molten resin is flown into the mold model to calculate the optimum molding conditions consisting of injection profile and pressure holding profile, and main molding variables during the molding process. The allowable upper limit value and the allowable lower limit value are set, and a trial molding test is performed based on these optimum molding conditions. If the main molding variables during molding deviate from the allowable upper limit value or the allowable lower limit value, the optimum molding Modify the conditions using a modification program prepared in advance and repeat the trial shot molding test until it falls within the above allowable range. When the molding variable is within the allowable range defined by the allowable upper limit value and the allowable lower limit value, the appearance quality is judged by the operator's visual observation, and if there is a defective item, the correction program or separately prepared. The optimum molding conditions are corrected again using the modified program, and the trial injection molding test is repeated. If there are no defective items, the final molding conditions are set as the optimum molding conditions and the injection molding is performed in the production process. Machine molding condition setting method. 2. The correction program is a resin flow analysis program having a function of correcting the main molding variable according to the degree of deviation from the permissible range of the main molding variable, and the appearance quality judgment item visually observed by an operator. The method for setting molding conditions for an injection molding machine according to claim 1, wherein a function for changing molding conditions according to the above is added.