JP3395589B2 - 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.

Recently, in addition to the trial and error method, an attempt is made to grasp a desired molding condition with a certain degree of accuracy by a simulation method concerning a flow analysis of a resin in a mold utilizing computer technology. As a conventional technique for obtaining optimum molding conditions by a similar method in patents prior to the present invention, for example, Japanese Patent Publication No.
No. 048 is mentioned.

In the method of this patent, a large number of molding tests are performed because a large number of setting condition factors are set and a large number of change levels are created for the molding test without setting a standard molding condition. The quality judgment of molded products is 100
The evaluation was complicated, with a score of 85 out of a perfect score.
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.

[0007]

The above-mentioned analysis method is advantageous because it uses idealized mathematical formulas and resin physical properties to perform calculations and uses a simplified mold model. There is a certain gap between the specified molding conditions and the optimum molding conditions in the actual operation, and it is highly possible that a good product cannot be made if molding is performed under the conditions obtained by analysis, and in the worst case, a large burr occurs due to overpack. In some cases, the mold may be seriously damaged, and the molded products obtained in actual operation may not always be 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.

[0008]

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 trial injection molding test is performed with a stroke shorter than this injection profile, and the appearance quality is judged visually by the operator. Check if there is any, and if there is a defective item, a prepared patch program or a separately prepared patch program. Use the ram to correct the stroke of the injection profile again, repeat the trial injection molding test until there are no defective items due to the stroke, complete the injection stroke adjustment of the first stage, and correct the final stroke. Perform a trial injection molding test again under the molding conditions consisting of the injection profile and the holding pressure profile, and perform visual quality judgment by the operator's visual inspection to check whether there are any defective items due to any molding conditions. If there is a defective item, use the correction program prepared in advance or the correction program prepared separately to correct the molding conditions again,
When the trial casting molding test is repeatedly performed until the defective items are eliminated and the molding condition adjustment of the second stage is completed and there are no defective items due to the setting of the molding conditions,
The final molding condition after the adjustment of the first stage and the second stage is completed is set as the optimum molding condition, which is the molding condition in the production process.

According to a second aspect of the present invention, in the first aspect, the correction program lengthens the injection stroke by several% when the defective item is a short shot when adjusting the injection stroke of the first stage, and the defective stroke is defective. Has a correction function that shortens the injection stroke by a few percent when the item is burr.
When adjusting the molding conditions of the secondary stage, if the defective item is burnt, the injection speed is slowed by a few percent, and if the defective item is a sink, the holding time is lengthened by a few percent or the holding pressure is set by a few percent. Increase the injection speed by a few percent when the defective item is a weld line or increase the holding pressure by a few percent, decrease the injection speed by a few percent when the defective item is a burr, and increase the injection speed when the defective item is a short shot. It has a modification function to modify each molding condition so as to increase by several percent.

[0010]

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, a trial injection molding test is performed with a stroke shorter than this injection profile, the appearance quality is judged by the operator's visual inspection, and it is confirmed whether there is a defective item due to the stroke. If there is, use the prepared modification program or the separately prepared modification program to perform the injection profile The stroke is corrected again, and the trial injection molding test is repeatedly performed until the defective items due to the stroke are eliminated, and the injection stroke adjustment of the first stage is completed. Under the following molding conditions, a trial injection molding test is performed again, and the appearance quality is judged visually by the operator to check whether there are any defective items due to all molding conditions. Modify the above molding conditions again using the modified program prepared or prepared separately, and repeat the trial molding test until the defective items are eliminated, and complete the molding condition adjustment of the second stage. If there are no defective items due to the setting of, Since the final molding conditions after completing the adjustment of the secondary stage were the molding conditions in the production process as the optimum molding conditions, the molding conditions obtained by the resin flow analysis were corrected by the first and second stages. Then, it is evaluated by two checks, a trial-casting molding test and the appearance quality judgment by the operator's visual inspection, and the molding conditions are adjusted to the optimum molding conditions that can obtain a molded product with sufficiently satisfactory quality, and it is used in actual operation. By doing so, it is possible to safely and reliably produce high-quality molded products in actual operation.

According to the second aspect of the invention, the correction program lengthens the injection stroke by several% when the defective item is a short shot and adjusts the injection stroke when the defective item is a flash when adjusting the injection stroke of the first stage. It has a correction function that shortens the stroke by several percent, and when adjusting the molding conditions of the secondary stage, the injection speed is reduced by several percent when the defective item is burnt, and the holding time is reduced when the defective item is sink mark. Increase by a few percent or increase the holding pressure by a few percent to increase the injection speed by a few percent if the defective item is a weld line or increase the holding pressure by a few percent, and increase the injection speed by a few percent if the defective item is a burr. Since it has a correction function to correct each molding condition so that the injection speed is increased by a few percent when the defective item is a short shot, it is not possible to judge the appearance quality of the test molding result. Because if the item comes automatically correct the molding condition can be more improved optimum molding conditions, it is convenient.

[0012]

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 is composed of 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 9 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.

In the vicinity of the tip of the nozzle 4, a mold 1 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 disposed in front of the nozzle 4, a resin pressure measured value, a mold pressure sensor 6b measured resin pressure 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 a molding condition setting method for an 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. You may make settings. This setting may be performed in the flow analysis simulation. Then, the optimum molding condition T in the actual molding is found and selected from the optimum molding condition S in the analysis by judging the defective item by the trial casting molding test over two stages and visually observing the appearance and correcting the condition by the correction program. It is the method of the present invention, which is determined by the procedure described below.

As shown in FIG. 2, when the mold model preparation is completed and the molding condition calculation by the resin flow analysis method is completed, the condition correction of the first stage (called "injection stroke adjustment") is started. Here, the injection stroke is the distance from the injection start position to the injection completion position (position to switch to the pressure holding process).

First, of the molding conditions obtained by the above resin flow analysis method, the injection stroke is, for example, 5
%, And other test conditions other than the injection stroke are the same as the above-mentioned molding conditions (injection profile and holding pressure profile), and a trial injection molding test is performed. Among the molding conditions initially obtained by the analysis, the reason why the trial shot molding test is performed by shortening only the injection stroke is to prevent damage to the mold due to the occurrence of large burrs due to overpack.

After the trial injection molding test is completed, the appearance quality of the molded product is judged by the operator, and it is judged whether or not there is a defective item due to the shortened stroke. For example, if there is a defective item such as “short shot” or “burr”, the control device 30 as shown in FIG.
Of the appearance quality judgment table (defective item list) shown on the CRT display screen is entered with the cursor or the mouse, and the injection stroke is corrected using the prepared correction program or a separately prepared correction program. To do.

This correction program lengthens the injection stroke by 5% when the defective item is a short shot and adjusts the injection stroke by 5% when the defective item is a burr when adjusting the injection stroke of the first stage. Correct so that

After the correction of the injection stroke, the trial injection molding test and the appearance quality judgment are performed again, and the above work is repeated until there are no defective items.

When the defective item disappears in the first stage and the injection stroke is determined, the condition correction of the second stage (referred to as "condition correction for defect avoidance") starts. First, a trial injection molding test is carried out using the determined injection stroke and the molding conditions obtained by the resin flow analysis method described above. In the trial injection molding test, sensors automatically measure and monitor the main molding variables during molding (injection speed in filling process, holding pressure in holding process, cushion amount, etc.). At this time, as described above, the injection speed in the filling process and the holding pressure or the cushion amount in the holding process, which are the main forming variables, are lower than the allowable lower limit value and the allowable upper limit value (allowable range) with respect to the optimum forming conditions. If you are setting, if you deviate from this allowable range,
A correction function for correcting the molding conditions is added to a correction program prepared in advance corresponding to the deviation amount, the molding conditions are corrected as appropriate, and the trial shot molding test is performed again.

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 less than the second item in this appearance quality judgment table, modify the molding conditions using the modification program prepared in advance, execute the trial shot molding test again, and then The appearance quality is judged by the operator. And until there are no defective items,
This work is repeated.

In the correction of the condition of the second stage, this correction program slows the injection speed by 10% when the defective item is burnt and lengthens the holding time by 10% when the defective item is sink mark. Alternatively, the holding pressure is increased by 5% and the injection speed is increased by 10% when the defective item is a weld line, or the holding pressure is increased by 5% and the injection speed is reduced by 5% when the defective item is a burr. Modify the molding conditions so that the injection speed is increased by 5% in the case of a short shot.

Through the two stages as described above, the trial stamping test is repeated while performing the checking work (when the allowable range is set, the main molding variables are within the initially set allowable range), and the appearance quality is When the inspection is also passed, the optimum molding condition T in actual molding is determined, and the actual operation is started under this molding condition.

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, the molding conditions that pass all appearance quality judgments through the two stages of the primary stage and the secondary stage based on the preset molding conditions. Is determined as the optimum molding condition T and the actual operation is performed, so that the molding condition for hitting a good product can be automatically and quickly set by anyone. According to the results obtained by performing the test according to the method of the present invention, the time required for setting the optimum molding conditions was 1/6 to 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.

[0032]

As described above, according to the molding condition setting method for the injection molding machine of the present invention, the optimum molding conditions for actual molding are determined based on the molding conditions obtained by the resin flow analysis. It can be set quickly, easily and easily without damaging the machine and does not require the knowledge of a trained 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 an injection profile and a holding pressure profile, and a stroke shorter than this injection profile. Perform a trial injection molding test with the operator to check the appearance quality by the operator's eyes and check if there is a defective item due to the stroke.If there is a defective item, a correction program prepared in advance or separately prepared. Modify the injection profile strokes again using the modified program The trial shot molding test is repeated until the defective items due to the conditions are eliminated, the injection stroke adjustment of the first stage is completed, and the trial shot molding is performed again under the molding conditions including the injection profile having the corrected final stroke and the pressure holding profile. Perform a molding test and visually check the appearance quality of the operator to see if there is a defective item due to the stroke.If there is a defective item, a modification program prepared in advance or a modification program prepared separately The molding conditions are corrected again by using, and the trial casting test is repeated until there are no defective items, and the molding condition adjustment of the second stage is completed, and there are no defective items due to the setting of the molding conditions. When the adjustment of the first stage and the second stage is completed, Molding condition setting method for an injection molding machine and the molding conditions in the production process of the final molding conditions as the optimum molding conditions. 2. The correction program lengthens the injection stroke by a few percent when the defective item is a short shot and shortens the injection stroke by a few percent when the defective item is a burr when adjusting the injection stroke of the first stage. It has a correction function, and when adjusting the molding conditions of the second stage, if the defective item is burnt, the injection speed is slowed by several percent, and if the defective item is sink mark, the holding pressure time is lengthened by several percent. Increase the holding pressure by a few percent and increase the injection speed by a few percent if the defective item is a weld line, or increase the holding pressure by a few percent and decrease the injection speed by a few percent if the defective item is a burr and the defective item is short-circuited. 2. The molding condition setting method for an injection molding machine according to claim 1, further comprising a correction function for correcting each molding condition so as to increase the injection speed by several percent when shot.