JPH1148300A - Method for setting molding condition of injection molder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make knowledge of a skilled operator unnecessary by a method wherein an optimum molding conditions in an actual molding is set without impairing a mold based on molding conditions obtained in resin flow analysis. SOLUTION: Correction for a condition of a primary stage (correction of an injection stroke) is started. An injection stroke in molding conditions obtained by a resin flow analytical method is shortened, for example, by about 5%, the other molding conditions excepting the injection stroke are provided in accordance with an injection profile and a dwell profile, and a trial molding test is executed. Then, correction of conditions for a secondary stage (correction of conditions for avoiding inferiority) is started. A trial molding test by a decided injection stroke and molding conditions obtained by the resin flow analytical method, is executed. In the case where a visual inspection test for quality is accepted by repeating the trial test after executing checking operation through two stages, an optimum molding condition T in actual molding is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in injection molding of a molten resin,
Set an injection profile in which the horizontal axis is the position of the injection screw and the vertical axis is the advance speed of the injection screw, and a holding pressure profile in which the horizontal axis is time and the vertical axis is the injection pressure. Injection is controlled by a filling step of injecting and filling the molten resin material into the mold cavity with a pressure holding step of applying pressure to the resin in the mold cavity after filling the molten resin in accordance with the pressure holding profile, and the 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 adjusted so that the speed changes in multiple stages based on the elapsed time from the start of injection or the advance position of the injection screw. It is set so as to change over time or according to the stroke position of the injection screw, and by adjusting the flow control valve, the injection cylinder is adjusted. Ston, that is, the injection speed of the injection screw is controlled, and the molten resin is filled into the mold cavity at a high speed so that the resin in the mold cavity does not entrain air. After that, the flow control valve is fixed at a relatively small opening and the pressure adjustment valve is used to adjust the oil pressure. The degree of opening of the pressure regulating valve is changed so that a predetermined pressure can be applied to the resin, and the molten resin is cooled in the mold cavity so that the resin shrinks and the shape and size of the product with respect to the size of the cavity shape An error is prevented from occurring and a large residual stress is not generated inside the product.

FIG. 6 shows that a molten resin flows from a screw head front part 22 of an injection molding machine 20 via a nozzle part 4 to a mold 10.
a shows a state immediately before injection filling into the cavity 8 formed by the a and 10b. Thereafter, an injection step is started, and hydraulic oil enters the injection cylinder 16 from the head side 16a of the injection cylinder 16, and the screw 1 is removed. Move it forward, nozzle part 4
Is transferred into the cavity 8. After the cavity 8 is filled with the molten resin, the process enters a pressure-holding step, in which pressure is applied to the resin in the screw head front portion 22 while replenishing the shrinkage due to cooling and solidification of the resin. What kind of resin inflow velocity pattern and pressure pattern are used to inject and fill the molten resin in such an injection process and a pressure-holding process depends on the quality of the resin molded product molded in the mold. In general, as described above, for example, in the injection process, it is set based on the relationship between the screw position and the screw advance speed, as shown in FIG. 7, and in the pressure holding process, as shown in FIG. In this case, the setting is made based on the relationship between the elapsed time and the holding pressure (oil pressure or resin pressure).

[0004] 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 is required to obtain molding conditions under which a good product can be stably obtained with good reproducibility. In order to understand the problem, various combinations of various molding conditions have been implemented by making use of expert knowledge to obtain a desired result by trial and error.

[0005] Recently, along with the trial and error method, an attempt has been made to grasp desired molding conditions with a certain degree of accuracy by a simulation method relating to a flow analysis of a resin in a mold utilizing computer technology. Prior arts in the patents prior to the present invention for finding the optimum molding conditions by the same method include, for example, Japanese Patent Publication No.
No. 048.

According to the method of this patent, a large number of setting condition factors are set without setting a molding condition as a reference, and a large number of change levels are created to perform a molding test. Increased quality of molded products is 100
The evaluation was also complicated, with 85 out of perfect scores.
Also, in order to determine the molding conditions that maximize the quality by multiple regression analysis from the results of many molding tests, complicated calculations had to be performed, which was not suitable for practical use.

[0007]

Since the above-described analysis method performs calculations using idealized mathematical expressions and resin physical properties, and performs calculations using simplified mold models, it is difficult to obtain the above-mentioned analysis methods. There is a certain gap between the determined molding conditions and the optimal molding conditions in the actual operation.There is a high possibility that non-defective products will not be obtained if molding is performed under the conditions obtained from the analysis. In the worst case, large burrs are generated due to overpacking. As a result, the mold may be seriously damaged, and moreover, the molded products obtained in actual operation may not always be satisfactory. Therefore, some measures to correct the molding conditions obtained by the above-described analysis method to the optimum molding conditions that can obtain a molded product that can be sufficiently satisfied in actual operation, and a quick, easy and easy setting procedure based on these measures are established. Means were urgently expected. An object of the present invention is to solve the above problems and to provide a method of setting optimum molding conditions that can obtain a molded product having satisfactory molded product quality in actual operation.

[0008]

In order to solve the above-mentioned problems, according to the first invention, in the first invention, a molten resin material is flow-pressed into a substantially closed mold cavity to form a molded product. This is a method of setting molding conditions of an injection molding machine that is repeatedly produced, in which a mold model in which a mold cavity shape is mathematically defined in advance is created, and a resin flow analysis is performed when a molten resin is flowed into the mold model. In addition to calculating the optimum molding conditions consisting of the injection profile and the holding pressure profile, a trial shot molding test is performed with a shorter stroke than this injection profile, and the appearance quality is visually judged by the operator, and the defective item caused by the stroke is determined. Check if there are any defective items, and if there are any defective items, use the prepared correction program or a separately prepared correction program. Using the ram, the stroke of the injection profile is corrected again, and the test punching test is repeated until no defective item due to the stroke is eliminated, and the injection stroke adjustment of the first stage is completed. Performing a test punching molding test again under the molding conditions consisting of the injection profile and the holding pressure profile having, performing visual appearance quality judgment by the operator visually, and confirming whether there is a defective item due to any molding conditions, If there is a defective item, correct the molding conditions again using a previously prepared correction program or a separately prepared correction program,
If the test condition adjustment of the second stage is completed by repeatedly performing the test molding test until no defective items are eliminated, 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 optimal molding condition, which is the molding condition in the production process.

According to a second aspect, in the first aspect, the correction program increases the injection stroke by several percent when the defective item is a short shot when adjusting the injection stroke of the first stage. It has a correction function that shortens the injection stroke by several percent when the item is burr,
In adjusting the molding conditions of the second stage, the injection speed is reduced by several percent when the defective item is burnt, and the dwell time is increased by several percent or the dwell pressure is reduced by several percent when the defective item is sink. If the defective item is a weld line, increase the injection speed by several percent or increase the holding pressure by several percent; if the defective item is a burr, reduce the injection speed by several percent; if the defective item is a short shot, increase the injection speed. It has a correction function to correct each molding condition so as to increase by several percent.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In the first aspect of the present invention, there is provided a method for setting molding conditions of an injection molding machine for repeatedly producing a molded product by flowing a molten resin material into a substantially hermetically sealed mold cavity by flow-pressing. A mold model in which a mold cavity shape is mathematically defined in advance is created, and a resin flow analysis is performed when a molten resin is caused to flow into the mold model, and an optimal molding including an injection profile and a pressure-holding profile is performed. In addition to calculating the conditions, a trial shot molding test was performed with a stroke shorter than the injection profile, the appearance quality was visually judged by the operator, and it was confirmed whether or not there was a defective item due to the stroke. If there is, use the previously prepared correction program or a separately prepared correction program to use the injection profile The stroke is corrected again, and the test punching test is repeated until no defective items due to the stroke are eliminated, and the injection stroke adjustment of the first stage is completed, and the injection profile having the corrected final stroke and the holding pressure profile are determined. Perform a trial molding test again under the same molding conditions, visually determine the appearance quality of the operator, check whether there is a defective item due to all molding conditions, prepare in advance if there is a defective item The molding conditions are corrected again by using the modified program or a separately prepared modification program, and the trial-shot molding test is repeated until no defective items are eliminated, and the molding condition adjustment of the second stage is completed. When there are no defective items due to the setting of the above, the first stage and the Since the final molding conditions after the completion of the adjustment of the second stage were set as the optimal molding conditions and the molding conditions in the production process, the molding conditions obtained by the resin flow analysis were corrected by the first stage and the second stage. And evaluated by two checks, a test casting test and visual quality judgment by the operator, and adjusted to the optimum molding conditions to obtain a molded product with satisfactory quality, and adopted for actual operation By doing so, it is possible to safely and reliably produce high-quality molded products in actual operations.

Further, in the second invention, the adjustment program increases the injection stroke by several percent when the defective item is a short shot and adjusts the injection stroke when the defective item is burr when adjusting the injection stroke of the first stage. It has a correction function that shortens the stroke by several percent. When adjusting the molding conditions of the second stage, the injection speed is reduced by several percent when the defective item is burnt, and the dwell time is reduced when the defective item is sink mark. Increase the holding pressure by several percent or increase the holding pressure by several percent. If the defective item is a weld line, increase the injection speed by several percent or increase the holding pressure by several percent, and if the defective item is a burr, increase the injection speed by several percent. In order to increase the injection speed by several percent when a defective item is a short shot, a correction function to correct each molding condition is provided. Because if the item comes automatically correct the molding condition can be more improved optimum molding conditions, it is convenient.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below 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 optimal molding conditions, FIG. 3 is an explanatory diagram of optimal molding conditions in an injection process, and FIG. 4 is an explanatory diagram of optimal molding conditions in a pressure-holding process. FIG. 5 is a display diagram on a 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 so as to be rotatable and forward and backward.
A nozzle 4 is attached to the tip of the nozzle. In addition, an injection cylinder 16 in which a piston 14 for moving the screw 1 forward and backward is inserted is mounted at a rear portion, and a screw rotation motor 5 for screw rotation 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 as a drive source to the screw rotation motor 5 is provided.

The hydraulic chamber of the injection cylinder 16 comprises a head-side hydraulic chamber 16a and a rod-side hydraulic chamber 16b.
The hydraulic chamber is supplied with hydraulic oil from a hydraulic pump (not shown) and is controlled by a hydraulic operating valve 11. The hydraulically operated valve 11 includes a head side hydraulically operated valve 11a communicating with the head side hydraulic chamber 16a and a rod side hydraulically operating valve 11b communicating with the rod side hydraulic chamber 16b. The head-side hydraulic chamber 16a of the injection cylinder 16 is used to measure the injection pressure during the injection process.
3 is attached.

Reference numeral 9 denotes a screw position sensor for measuring the forward and backward traveling 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 thereon. The screw head 18 has a substantially conical shape toward the tip, and the rear side of the conical shape (the right side in the figure) is stepped. The small diameter part 1
A check ring 2 slidable in the axial direction is fitted into 8a.

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

In the injection device 20, a measured value of the resin pressure by a nozzle pressure sensor 6a disposed in front of the nozzle 4, a measured value of the resin pressure by a pressure sensor 6b in the mold, and a hydraulic pressure sensor 13 by an injection cylinder head side hydraulic sensor. Injection molding that receives various measured values of oil pressure and oil pressure from the screw motor driving oil pressure sensor 15 or measured values from other sensors and compares them with target values to issue various control commands. A machine control device 30 is provided.

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

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 having the above construction will be described with reference to the flowchart of FIG.
FIG. 2 is a flowchart showing the procedure for setting the optimum forming conditions. Prior to the actual operation, the optimum forming conditions for analysis are first set. For the optimum molding conditions, a mold model that mathematically defines the mold cavity shape is created, and the optimal molding conditions in the analysis are calculated by using the flow analysis simulation method for resin flow in the mold using CAE technology. I do. The molding conditions include an injection profile in the injection filling step and a pressure holding profile in the pressure holding step.

Next, in the molding process of the injection profile and the holding pressure profile set as described above,
As shown in FIGS. 3 and 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 screw most advanced position in the pressure-holding process. Settings may be made. 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 optimal molding condition S in the analysis by judging a defective item by a test punching molding test over two stages and visually observing the appearance and correcting the condition by a correction program. This is the method of the present invention, which is determined by the procedure described below.

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

First, out of the molding conditions obtained by the above-described resin flow analysis method, the injection stroke is set to, for example, 5
The test molding test is performed under the same molding conditions (injection profile and pressure-holding profile) as the molding conditions other than the injection stroke. The reason why the test stroke molding test is performed by shortening only the injection stroke among the molding conditions obtained by the analysis first is to prevent the mold from being damaged due to the generation of a large burr due to the overpack.

After the trial molding test, the appearance quality of the molded product is determined by the operator, and it is determined whether there is a defective item due to the shortened stroke. For example, if there are defective items such as “short shot” and “burr”, the control device 30 as shown in FIG.
Of the appearance quality judgment table (defective item list) shown on the CRT display screen with a cursor or a mouse, and correct the injection stroke using a previously prepared correction program or a separately prepared correction program. Do.

In the correction program, when adjusting the injection stroke of the first stage, for example, the injection stroke is increased by 5% when the defective item is a short shot, and the injection stroke is reduced by 5% when the defective item is burr. To be modified.

After the injection stroke has been corrected, the test molding test and the appearance quality judgment are performed again, and the above operation is repeated until there are no defective items.

When the defective item is eliminated in the first stage and the injection stroke is determined, the process proceeds to the second stage condition correction (referred to as "condition correction for defect avoidance"). First, a test injection molding test is performed using the determined injection stroke and the molding conditions obtained by the above-described resin flow analysis method. In the trial molding test, the main molding variables during molding (such as the injection speed in the filling process, the holding pressure in the holding process, the cushion amount, etc.) are automatically measured and monitored by sensors. At this time, as described above, the injection speed in the filling step, the holding pressure in the holding step, the cushion amount, and the like, which are the main molding variables, are the allowable lower limit value and the allowable upper limit value (allowable range) with respect to the optimum molding conditions. If you are outside of this tolerance,
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 test punching test is performed again.

In this way, for a shot in which the main molding variables are within the allowable range, the operator visually inspects the appearance quality of the molded product. For example, as shown in FIG. Is input to the appearance quality judgment table called on the CRT screen. If there are any defective items below the second item in the appearance quality judgment table, the molding conditions are corrected and changed using a correction program prepared in advance, and a test punching molding test is executed again. The appearance quality is determined by the operator. And until there are no bad items
This operation is repeated.

In this correction program, in the condition correction of the second stage, for example, if the defective item is burnt, the injection speed is reduced by 10%, and if the defective item is sink, the dwell time is increased by 10%. Alternatively, increase the holding pressure by 5%, increase the injection speed by 10% when the defective item is a weld line, or increase the holding pressure by 5%, and reduce the injection speed by 5% when the defective item is a burr, Modify the molding conditions to increase the injection speed by 5% for short shots.

Through the above two stages, the test hitting test is repeated while performing a check operation (if an allowable range is provided, the main molding variables enter the initially set allowable range), and the appearance quality is improved. If the inspection is passed, the optimum molding condition T in the actual molding is determined, and the actual operation is started under the molding conditions.

As the resin flow analysis program, a commercially available in-mold flow analysis program "MOLD FLOW program" can be used. Further, the correction program usually has a function of modifying the main molding conditions according to the degree of deviating from the allowable range of the main molding variables and modifying the main molding conditions according to the defective item 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 an injection molding machine, it is needless to say that the present invention may be applied to a die casting machine or a squeeze cast machine for forming a metal material.

As described above, in the present invention, the molding conditions that have passed all the appearance quality judgments through the two stages of the primary stage and the secondary stage based on the molding conditions set in advance. Is determined as the optimum molding condition T and the actual operation is performed, so that anyone can automatically and quickly set the molding conditions for hitting a good product. 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 setting the conditions by the conventional skilled operator. Also, this setting work procedure is almost completely automated, and is easy and easy to implement.

[0032]

As described above, according to the molding condition setting method for an injection molding machine of the present invention, the optimum molding conditions in actual molding are determined based on the molding conditions obtained by resin flow analysis. Can be set quickly and conveniently without damaging the device and does not require the knowledge of a skilled operator.

[Brief description of the 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 step according to an embodiment 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 step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw 2 Check valve 3 Barrel 4 Nozzle 5 Screw rotation motor 6a Nozzle pressure sensor 6b In-mold pressure sensor 6c Nozzle temperature sensor 6d Mold temperature sensor 7 Runner part 8 Mold cavity 9 Position sensor 10 Mold 10a Fixed mold 10b Movable mold 11a Head side hydraulic valve 11b Rod side hydraulic valve 12 Hopper 12a Resin pellet 13 Injection cylinder head side hydraulic sensor 14 Piston 16 Injection cylinder 16a Head side chamber 16b Rod side chamber 18 Screw head 18a Small diameter section 20 Injection device 22 Screw head Front part 30 Control device 100 Injection molding machine L Lower limit condition S Optimal molding condition in analysis T Optimal molding condition in actual molding U Upper limit value condition

Claims (2)

[Claims] 1. A method for setting molding conditions of an injection molding machine for repeatedly producing a molded product by flowing a molten resin material into a substantially closed mold cavity by flow-pressing, wherein a shape of the mold cavity is mathematically determined in advance. Creates a defined mold model, performs resin flow analysis when a molten resin flows through the mold model, calculates the optimal molding conditions consisting of the injection profile and the pressure-holding profile, and has a stroke shorter than the injection profile. Perform a test punching molding test to determine the appearance quality by visual inspection of the operator, check if there are any defective items due to the stroke, and if there is a defective item, prepare a prepared correction program or separately The stroke of the injection profile is corrected again using the corrected program The test molding test is repeated until the defective item due to the condition disappears, the injection stroke adjustment of the first stage is completed, and the test molding is again performed under the molding condition including the injection profile having the corrected final stroke and the pressure holding profile. Perform a molding test to visually determine the appearance quality of the operator, check whether there is a defective item due to the stroke, and if there is a defective item, a correction program prepared in advance or a separately prepared correction program The molding conditions are corrected again by using the above method, and the trial-shot molding test is repeated until no defective items are eliminated, and the adjustment of the molding conditions of the second stage is completed, and there is no defective item 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 according to claim 1, wherein, when adjusting the injection stroke of the first stage, the injection stroke is lengthened by several percent when the defective item is a short shot, and the injection stroke is shortened by several percent when the defective item is burr. It has a correction function, and when adjusting the molding conditions of the second stage, if the defective item is burnt, reduce the injection speed by several percent, and if the defective item is sink, extend the dwell time by several percent, or Increasing the holding pressure by several percent, increasing the injection speed by several percent when the defective item is a weld line, or increasing the holding pressure by several percent, decreasing the injection speed by several percent when the defective item is burr, shorting the defective item 2. A molding condition setting method for an injection molding machine according to claim 1, further comprising a modification function for modifying each molding condition so as to increase the injection speed by several percent in the case of a shot.