JP2598745B2 - Method and apparatus for setting molding conditions of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for setting molding conditions of an injection molding machine using a mold whose mold data is unknown.

[0002]

2. Description of the Related Art Generally, there are cases where mold data is known or unknown for molds used in an injection molding machine. For example, when manufacturing a product, if all manufacturing processes including mold design are provided in-house, mold data such as cavity capacity can be known from a mold drawing or a model. However, in a manufacturing company or the like having only a manufacturing department, when receiving a molding commission, there are cases where only the mold is delivered, and in this case, the mold data is often unknown.

When setting molding conditions such as an injection pressure, an injection speed, and a measured value, if mold data such as a cavity capacity is known, the molding conditions such as a measured value are somewhat provisional. Although molding can be performed by setting appropriate initial conditions, it is not easy to set the initial conditions when mold data is unknown. For this reason, conventionally, a skilled operator visually inspects the mold cavity and the like, sets initial conditions such as injection speed and injection pressure based on intuition and experience, and sets a small measurement value at first to perform molding. The desired molding conditions were set by trial and error by repeating the molding while gradually increasing the measured value while observing the filling state of the molded article.

[0004]

However, the above-mentioned conventional method has the following problems since it has to rely on the intuition and experience of a skilled operator.

[0005] First, since the operator who performs the setting operation requires considerable skill, the operators who can make the setting are limited. In addition, since the setting operation cannot be easily performed even by a skilled operator, the setting time is prolonged, the productivity is reduced, and the manufacturing cost is increased. In addition, useless resources and energy are consumed.

[0006] Second, if molding conditions such as injection pressure and measured value are excessively set due to a setting error or improper setting, abnormal pressure is applied inside the mold, which may cause damage to the mold. And it is inferior in safety.

The present invention has solved the problems existing in the prior art as described above, so that even a low-skilled operator can easily and reliably set molding conditions, greatly shorten the set time, and reduce the production time. It is an object of the present invention to provide a method and an apparatus for setting molding conditions of an injection molding machine, which can improve productivity, reduce manufacturing costs, save resources and energy, prevent damage to a mold, and improve safety.

[0008]

A method for setting molding conditions of an injection molding machine according to the present invention comprises a plurality of ranks corresponding to the degree of defective filling of a molded article and a direction for eliminating defective filling corresponding to each rank. Set multiple change amounts to change specific molding conditions, select the defective filling rank of the molded product at the time of setting the molding conditions, and change the molding conditions according to the change amount corresponding to the selected rank In addition, a re-molding cycle of performing re-molding under changed molding conditions is repeated until a non-defective product is molded, and the size of the molding condition when a non-defective product is molded is used as the molding condition to be set.

In this case, it is desirable that the magnitude of each change amount is set to be different so that the change amount increases in accordance with the rank having a high degree of filling failure. The molding conditions can be applied to an injection pressure or an injection speed. on the other hand,
As initial conditions, it is desirable to perform molding by setting the injection speed to the first speed value on the high speed side, setting the injection start position of the screw to the rearmost position, and setting the injection pressure to the one pressure value on the low pressure side.

On the other hand, the molding condition setting device M of the injection molding machine according to the present invention sets a plurality of ranks for the degree of defective filling of the molded product and specific molding conditions in a direction corresponding to each rank to eliminate the defective filling. Change amount setting means A for setting a plurality of change amounts to be changed, defective rank selecting means B for selecting a rank of defective filling of a molded article, and molding for changing molding conditions by a change amount corresponding to the selected rank. It is characterized by comprising a condition changing means C and a molding condition setting means D for setting the molding conditions using the magnitude of the molding conditions at the time of molding a good product.

In this case, it is desirable that the change amount setting means A sets the change amounts to be different from each other so that the change amounts become large in accordance with the rank of the degree of the defective filling. The molding conditions can be applied to the injection pressure or the injection speed.

[0012]

According to the molding condition setting method and apparatus M according to the present invention, the change amount setting means A sets a plurality of ranks for the degree of defective filling of the molded article in advance, and corresponds to each rank. A plurality of change amounts are set for changing specific molding conditions in a direction to eliminate poor filling. As a result, if an arbitrary rank is selected from a plurality of ranks, the molding condition is automatically changed by a corresponding change amount.

Therefore, for example, when a mold with unknown mold data is loaded at the time of setting the molding conditions, as an initial condition, the injection speed is set to a high speed value and the injection start position of the screw is set to the last. At the retreat position, the injection pressure is set to one pressure value on the low pressure side, and molding is performed. When the first molded product is obtained, this molded product is visually observed, and the degree of defective filling is determined by the defective rank selecting means B. Can be selected. As a result, the molding condition changing means C changes the size of the molding condition by the change amount corresponding to the selected rank. By repeating the re-molding cycle for re-molding under the changed molding conditions, a good product can be obtained. That is, the magnitude of each change amount is different from each other, and is set to be large in accordance with the rank having a high degree of defective filling. Good products can be molded. Therefore, the molding condition is set by the molding condition setting means D using the magnitude of the molding condition when a good product is molded.

[0014]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a schematic configuration of an injection molding machine 1 that can execute a molding condition setting method according to the present invention will be described with reference to FIG.

The injection molding machine 1 has a machine base 3, and the machine base 3
Is provided with an injection device 4 on one side of the upper surface and a mold 5 with unknown mold data covered with a safety cover 6 on the other side of the upper surface.
Is provided. In this case, the mold 5 is supported by a mold clamping device that does not appear in the drawing, and the injection device 4 is
To move forward and backward. The injection device 4 has an injection nozzle 9 at the tip.
Is provided with a heating cylinder 8 having a hopper 10 at the rear, and a screw is built in the heating cylinder 8. On the other hand, a screw driving device 11 for rotating and moving the screw forward and backward is provided at the rear end of the heating cylinder 8. As the screw driving device 11, an electric driving type using a servomotor and a hydraulic driving type using a hydraulic circuit are known.

On the other hand, in FIG. 3, M is a molding condition setting device. In the molding condition setting device M, a controller 12 is built in the machine base 3 and controls the entire injection molding machine 1. Reference numeral 13 denotes an input device (keyboard) attached to the side panel 3p of the machine base 3, and a controller 12
Connect to The input device 13 and the controller 12 include a setting function for setting various conditions, and in particular, according to the present invention, a plurality of ranks for the degree of the filling failure of the molded article and the injection pressure in a direction corresponding to each rank to eliminate the filling failure. A change amount setting means A for setting a plurality of change amounts for changing the magnitude of (specific molding conditions) is provided, and the input device 13 is provided with a failure rank selection means B for selecting a filling failure rank of a molded article. Further, the controller 12 sets the molding condition by using the molding condition changing means C for controlling the molding condition to be changed according to the change amount corresponding to the selected rank and the size of the molding condition when a good product is molded. The molding condition setting means D is configured. Therefore,
The input device 13 has selection keys K1 and K for selecting the type of filling failure and the rank for each degree of filling failure.
2, K3 is provided, and the controller 12 is set with a plurality of change amounts corresponding to each rank for changing the injection pressure in a direction to eliminate the filling failure.

More specifically, when the filling failure is a short shot, as shown in FIG. 1, the degree of the short shot is classified into three levels of "large", "medium" and "small".
When "Large", the pressure change rate (change amount) is "+ 20%",
When "medium", the pressure change rate is set to "+ 10%", and when "small", the pressure change rate is set to "+ 5%". In this case, the ranks are set to “large”, “medium”, and “small”, but of course, they may be converted into numerical values. The pressure change rate is used as the change amount because the injection pressure is usually set as a ratio to the maximum pressure. Therefore, for example, if “large” is selected as the degree of the short shot, the pressure change rate “+ 20%” is selected, and 20% is added to the set injection pressure ratio. As described above, the change amount may be set as an absolute amount or a ratio, or may be changed by adding or subtracting or multiplying or dividing the injection pressure.

Similarly, in the case of overfilling, as shown in FIG. 2, the degree of overfilling is classified into three levels of "small", "medium" and "large". When the pressure change rate is “−2%”, when “medium”, the pressure change rate is “−5%”,
When "large", the pressure change rate is set to "-10%". As described above, in any case, the pressure change rate is set so as to increase in accordance with the rank in which the degree of defective filling is large.

On the other hand, 14 is a screw position detector,
For example, in the case of an electric drive type, a rotary encoder that detects the number of rotations of a servomotor can be used, and in the case of a hydraulic drive type, a linear scale that directly detects a screw position can be used. The screw position detector 14 is directly connected to the controller 12, and is also connected to the controller 12 via the speed converter 15. The speed converter 15 has a function of differentiating the position signal from the screw position detector 14 and converting it into a screw speed signal.

An injection pressure detector 16 is, for example, a load cell for detecting the back pressure at the rear end of the screw in the case of the electric drive type, and a hydraulic pressure for detecting the hydraulic pressure of the hydraulic cylinder in the case of the hydraulic drive type. Sensors and the like can be used. Note that 17
Is a display attached to the side panel 3p, which performs various displays and is used as an auxiliary device of the input device 13. The controller 12 is connected to the system computer 18 by an optical communication system (wireless system) or the like.

Next, the overall procedure for setting the molding conditions including the molding condition setting method according to the present invention will be described with reference to FIGS.

FIG. 4 is a flowchart showing a procedure for setting molding conditions. When setting the molding conditions, the input device 1
3. Further, using the display 17, input known data relating to the molding material, the specification screw, and the like. The controller 12 stores a database relating to material characteristics, molding machine performance specifications, basic molding conditions, and the like. The controller 12 uses the input known data and the stored database to store temperature-related molding conditions, such as the maximum stroke of the screw. Controller 1
Set to 2. The molding conditions relating to the temperature, that is, the heating cylinder temperature and the mold temperature are automatically set based on the type of the molding material.

On the other hand, the selection key Ks on the input device 13
The initial condition setting mode is selected by pressing, and the initial conditions are set (steps 21 and 22). The setting of the initial condition is performed according to the flowchart shown in FIG.

First, as an injection condition, the injection speed is set to the first speed value Vh on the high speed side (step 41). in this case,
The first speed value Vh on the high speed side is higher than the middle point of the set range in the injection molding machine to be used, and preferably a value of 90% or more with respect to the maximum speed is selected. Further, the injection start position of the screw is set to the last retreat position Xb (step 42). In this case, the last retreat position Xb does not mean a complete rear end, but is a concept including an arbitrary rear position at which a sufficient amount of resin can be measured with respect to the volume of the mold 5. Furthermore, the injection pressure is set to the one pressure value Pd on the low pressure side (step 43). In this case, the one pressure value Pd on the low pressure side is lower than the middle point of the set range in the injection molding machine to be used, and is desirably set to a value of 30% or less with respect to the maximum pressure. In addition to the above settings, in the setting of the initial conditions, various molding conditions such as a pressure-holding switching position, a back pressure, a cooling time, and a screw rotation speed are set (step 44).

Further, a set speed Vs and a set time Ts for detecting the injection end position Xf of the screw are set. The set speed Vs is a threshold value for the injection speed for detecting the completion of the filling of the mold 5 with the resin, and can be set to several m / sec, which is almost a stopped state. The set time Ts is a time for ensuring more reliable filling after the speed becomes equal to or less than the set speed Vs, and can be set to, for example, about several seconds.

Next, the back pressure is turned off (zero), and measurement is performed without back pressure (step 23). At this time, the screw retreats to the last retreat position Xb. Then, by selecting the semi-automatic molding mode, the injection device 4 (the injection nozzle 9) advances (steps 24 and 25). On the other hand, the injection is started by the nozzle touch. That is, the screw advances according to the set initial conditions, and the resin is injected and filled into the mold 5 (step 26). At this time, the controller 12 controls the speed converter 1
The injection speed at filling obtained from 5 is monitored. The injection speed is much higher than the set speed Vs when the mold 5 is being filled with the resin, and rapidly decreases to be equal to or lower than the set speed Vs when the filling of the resin is completed. Therefore, the injection speed is monitored, and when the injection speed falls below the set speed Vs,
The set time Ts is counted (steps 27 and 28). Then, when the set time Ts has elapsed, the injection end position Xf of the screw is monitored (steps 29 and 30). In this case, the injection pressure obtained from the injection pressure detector 16 may be monitored by setting the set pressure Ps as the threshold. In other words, the injection pressure is much smaller than the set pressure Ps while the mold 5 is being filled with the resin. However, when the filling of the resin is completed, the injection pressure rises rapidly and becomes equal to or higher than the set pressure Ps. Therefore, based on the fact that the injection pressure has reached the set pressure Ps, the screw injection end position can be detected in the same manner as described above.

Next, the injection pressure (molding condition) is changed (step 31). In this change process, the injection pressure (one pressure value Pd) set on the low pressure side as an initial condition is increased to a required level, and finally a size usable for molding conditions is obtained. Is shown in a flowchart.

At this time, first, the back pressure is turned on, weighing is performed with the back pressure applied, the injection device 4 (the injection nozzle 9) is retracted, and the mold 5 is opened (step 5).
1, 52, 53). Then, while judging a defective filling of the taken-out molded article, a necessary data collection, for example, a data collection of a wall thickness, a gate pressure and the like is performed (Step 5).
4). At this time, the cooling time is automatically calculated from the collected data on the thickness and the gate pressure.

On the other hand, the molded product is visually inspected to determine whether or not a defective filling has occurred. If a short shot has occurred due to insufficient filling, processing for increasing the injection pressure is performed (steps 55 and 56). That is, the degree of the short shot is determined. For example, if the degree is “large”, the corresponding selection key K1 on the input device 13 may be pressed.
In this case, the injection pressure is set to the initial pressure value P as the initial condition.
Since the single pressure value Pd is set to 20%, the controller 12 adds the pressure change rate of 20% to the injection pressure of 20% to set the injection pressure to 40%. change. Then, reshaping is performed by the changed (increased) injection pressure, that is, steps 25 to 31 shown in FIG.
Then, a reshaping cycle, which is the process of steps 51 to 54 shown in FIG. 6, is executed (step 57). Then, if a short shot has further occurred in the molded product, a process of increasing the injection pressure is performed again. That is, if the degree of the short shot is “medium”, similarly, 10% of the pressure change rate is added to the injection pressure,
Perform a reshaping cycle. Since the magnitude of each pressure change rate is different from each other and is set to be large corresponding to the rank with a high degree of filling failure, if the remolding cycle after changing the injection pressure is repeated, the rank to be selected is selected. Gradually decreases, and finally a good product can be obtained (step 58).

On the other hand, when the molded article is visually inspected and a filling failure such as a burr due to overfilling has occurred, a process for reducing the injection pressure is performed (steps 59 and 60). In this case, the degree of overfill is determined and, for example, the degree is “small”.
Then, by pressing the selection key on the input device 13, the controller 12 subtracts 2% of the pressure change rate from the set injection pressure magnitude. Then, reshaping by the changed (reduced) injection pressure, that is, the reshaping cycle is repeated until a good product is obtained (steps 61 and 6).
2).

Therefore, if a good product is finally obtained, the controller 12 takes in the injection end position Xf at that time obtained from the screw position detector 14, and calculates the injection stroke from the obtained injection end position Xf and the last retreat position Xb. Si (= X
b-Xf) is calculated, and the cushion value Sc set in advance is added to obtain the weighing value Md. Then, the measured value Md is used as a molding condition by the controller 12.
Set to.

Further, the molding conditions are determined by using the injection pressure and the injection speed at the time when finally a non-defective product is obtained, and the determined molding conditions are set in the controller 12. In this case, an average injection speed in the injection stroke Si when a good product is obtained is obtained. The injection speed is set to the first speed value Vh on the high speed side according to the initial conditions. However, since the injection speed during actual molding is much lower than this, an average injection speed is obtained, and the obtained injection speed is calculated. The molding conditions are set in the controller 12. In this case, the average injection speed may be obtained by dividing the injection speed sampled every fixed short time by the number of times of sampling, or obtaining the area of the speed characteristic with respect to the screw position, and dividing this area by the position to obtain the average. It may be.

On the other hand, the injection pressure is set by adding the correction pressure. The injection speed is set to the first speed value on the high-speed side according to the initial condition, and is set after averaging as described above. Therefore, the average injection speed is smaller than the first speed value for the initial condition. Therefore, in order to stabilize the reduced injection speed, a constant override pressure is added to the injection pressure as a correction pressure in consideration of a fluctuation pressure based on an override characteristic of a proportional pump or the like. In the case of a proportional pump used for a hydraulic drive type, usually, a value of about 10% can be added (step 32).

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, although the injection pressure was illustrated as a specific molding condition,
The same applies to the case of setting the injection speed. Also,
As an example of using a mold whose mold data is unknown, the injection speed was initially set to the first speed value on the high speed side, the injection start position of the screw was set to the last retreat position, and the injection pressure was initially set to the single pressure value on the low pressure side. However, if the mold data is known, other settings may be made. In addition, it is possible to arbitrarily change the detailed configuration, method, and the like without departing from the gist of the present invention.

[0036]

As described above, the method for setting molding conditions of an injection molding machine according to the present invention comprises a plurality of ranks for the degree of defective filling of a molded article and a direction for eliminating defective filling corresponding to each rank. Set multiple change amounts to change specific molding conditions, select the defective filling rank of the molded product at the time of setting the molding conditions, and change the molding conditions according to the change amount corresponding to the selected rank In addition, the re-molding cycle of re-molding under the changed molding conditions is repeated until a non-defective product is molded, and the size of the molding condition when the non-defective product is molded is used as the molding condition to be set. It has a remarkable effect.

The molding conditions can be easily and reliably set even by an operator with low skill, and the setting time can be greatly reduced, productivity can be improved, manufacturing costs can be reduced, and resources and energy can be saved.

Since setting errors and improper settings are eliminated, damage to the mold can be prevented and safety can be improved.

Further, the molding condition setting device of the injection molding machine according to the present invention changes a plurality of ranks with respect to the degree of defective filling of a molded product and specific molding conditions in a direction corresponding to each rank so as to eliminate the defective filling. Change amount setting means for setting a plurality of change amounts to be performed, defective rank selecting means for selecting a rank of defective filling of a molded article, and molding condition changing means for changing molding conditions by a change amount corresponding to the selected rank. When,
Since the apparatus is provided with the molding condition setting means for setting the molding condition using the magnitude of the molding condition when a non-defective product is molded, a remarkable effect that the molding condition setting method can be easily and reliably implemented.

[Brief description of the drawings]

FIG. 1 is a principle explanatory diagram for explaining a molding condition setting method according to the present invention,

FIG. 2 is another principle explanatory diagram for explaining the molding condition setting method;

FIG. 3 is a configuration diagram of an injection molding machine that can execute the molding condition setting method,

FIG. 4 is a flowchart showing an overall procedure for setting molding conditions;

FIG. 5 is a flowchart showing a procedure for setting an initial condition;

FIG. 6 is a flowchart including a procedure for setting molding conditions by a molding condition setting method according to the present invention;

[Explanation of symbols]

 1 Injection molding machine M Molding condition setting device A Change amount setting means B Defect rank selecting means C Molding condition changing means D Molding condition setting means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Shiozawa 2110, Nanjo, Nanjo, Hanashi-gun, Nagano Prefecture Nissei Plastics Industry Co., Ltd. Inside the Industrial Co., Ltd. (72) Inventor Fumihiro Kobayashi 2110 Nanjo Nanjo, Sasaka-cho, Hanishina-gun, Nagano Pref. Nissei Plastic Industry Co., Ltd. JP, A) JP-A-3-164223 (JP, A) JP-A-4-209004 (JP, A) JP-A-3-132325 (JP, A) JP-A 1-310928 (JP, A) JP Hei 4-201314 (JP, A) JP-A-63-242620 (JP, A)

Claims (7)

(57) [Claims] 1. A method according to claim 1, further comprising: setting a plurality of ranks for the degree of defective filling of the molded article and a plurality of change amounts for changing specific molding conditions in a direction corresponding to each rank to eliminate the defective filling. When setting the conditions, select the rank of defective filling of the molded product, change the molding conditions according to the change amount corresponding to the selected rank, and perform a remolding cycle that remolds according to the changed molding conditions. A molding condition setting method for an injection molding machine, wherein the magnitude of the molding condition when a good product is molded is used as the molding condition to be set. 2. The injection molding machine according to claim 1, wherein the amount of each change is set to be different so that the amount of change is large in accordance with the rank of the degree of the defective filling. Molding condition setting method. 3. The molding condition setting method for an injection molding machine according to claim 1, wherein the molding condition is an injection pressure or an injection speed. 4. As initial conditions, molding is performed by setting the injection speed to the first speed value on the high speed side, setting the injection start position of the screw to the last retreat position, and setting the injection pressure to the one pressure value on the low pressure side. The method for setting molding conditions for an injection molding machine according to claim 1. 5. A change amount setting means for setting a plurality of ranks for the degree of defective filling of a molded article and a plurality of change amounts for changing a specific molding condition in a direction corresponding to each rank to eliminate the defective filling; A defective rank selecting means for selecting a rank of filling failure of the molded article, a molding condition changing means for changing the molding condition by a change amount corresponding to the selected rank, and a size of the molding condition when a good product is molded. A molding condition setting device for an injection molding machine, comprising: molding condition setting means for setting molding conditions by using the molding condition setting device. 6. The change amount setting means sets the amount of each change amount differently so that the change amount increases in accordance with a rank having a high degree of filling failure. A molding condition setting device for an injection molding machine as described in the above. 7. The molding condition setting device for an injection molding machine according to claim 5, wherein the molding condition is an injection pressure or an injection speed.