JP2015134438A - Automatic calculation method for mold protection set value in injection molding machine, and injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic calculation method for a mold protection set value in an injection molding machine automatically calculating a control upper limit torque in an adequate range.SOLUTION: A process of closing a mold at a torque initial setting value to actually measure an initial mold-closing time, and another process of closing the mold at the newest halved torque to actually measure the mold-closing time are repeated until the newest mold-closing time when the previous mold-closing time is made to be a reference increases at the rate of more than 10%. Then, the newest torque is multiplied by a prescribed coefficient when satisfying such conditions that the difference between the rating output ratios of the previous and newest torques is within 3% and further, the newest mold-closing time when the initial mold-closing time is made to be the reference increases at the rate of within 10%, and when the conditions are not satisfied, the mold is closed at the newest torque increased in the range of 1% to 3% of the rating output ratio of the previous torque to actually measure the newest mold-closing time. The newest torque satisfying the above conditions is automatically searched by repeating such processes. The control upper limit torque of mold-closing/opening control is determined by multiplying the searched newest torque by the prescribed coefficient.

Description

  The present invention relates to a mold protection set value automatic calculation method for an injection molding machine, and an injection molding machine.

  Injection molding is a method of obtaining a molded product by injecting and injecting a heat-melted material into a mold, cooling and solidifying the material, and is suitable for mass production of products having complicated shapes. The injection molding material includes resin, metal, or a composite material thereof. In general, injection molding is performed in the order of mold closing and clamping, injection, holding pressure, cooling, metering, mold opening, and removal, and a product is continuously produced by repeating this molding cycle. And productivity becomes high, so that a molding cycle is short. Here, the mold closing is an operation for quickly closing the opened mold with a low pressure, and the mold clamping is an operation for clamping the closed mold with a pressure larger than the pressure during the mold closing operation. That is.

  In the molding cycle, the mold closing time is the time required to close the mold and clamp the mold to the mold closing limit position after starting to close the mold opened to the mold opening limit position. The reference mold closing time is required to perform mold closing from the mold opening limit position to the mold closing position at the initial torque setting value on the first shot at the start of the molding cycle or on the first shot after changing the mold opening / closing setting. It was time. The mold open limit position is a position where the mold is completely opened. The mold closing position is a position where the mold is completely closed, and is the origin.

  Of the peak torques in mold closing and mold clamping, the reference torque is the first shot torque at the start of the molding cycle or the first shot torque after the mold opening / closing setting is changed. The control upper limit torque is an upper limit value of the output of the driving device of the mold opening / closing unit in a series of operations from mold closing to mold clamping in the mold opening / closing control, and is a value calculated for mold protection. In this specification, the peak torque in mold closing is expressed as torque. The unit of torque is N · m (Newton meter). Torque may be displayed as an absolute value or a relative value. In this specification, the torque is expressed in%. For example, the torque is displayed in% at a rate when the rated output of the driving device of the mold opening / closing unit is 100%.

  The injection molding machine is mainly divided into a mold opening / closing unit and an injection unit. The mold opening / closing unit is a unit that opens / closes and projects the mold, and the mold opening / closing method includes a toggle method and a direct pressure method. The injection unit is a device that heats and melts a material and injects it into a mold.

  There are two types of driving devices for the mold opening / closing unit: a hydraulic type and an electric type. The electric type operates with a servo motor and a ball screw. The electric type has advantages such as reduced power consumption and noise, better response and repeatability than the hydraulic type.

  In mold clamping, the movable mold is strongly pressed against the fixed mold in order to withstand high injection pressure, and a strong surface pressure is applied to the mating surfaces of the mold. That is, in mold clamping, a strong mold clamping force of ton order is applied to the mold. Here, if foreign matter adheres to the mating surface of the mold during the opening and closing operation of the mold, if the mold is clamped as it is, a strong mold clamping force concentrates on a single point that contains the foreign matter, and the mold is aligned. It may lead to a mold breakage accident that damages the surface and breaks the mold. For this, a method of detecting that a foreign object has adhered to the mating surface of the mold by measuring the position where the movable mold and the fixed mold are combined can be considered, but the mold has the property of thermal expansion, Due to changes in mold temperature and mold ambient temperature, changes in molding conditions, changes in temperature conditions, etc., errors occur over time, making it difficult to accurately grasp the position of the mold mating surface. Since the mold is a very expensive and important tool, it is the most important issue to prevent the above-mentioned mold breakage accident. Therefore, efforts are made to calculate the control upper limit torque and set the upper limit value of the mold clamping force to protect the mold from being damaged.

  Patent Document 1 discloses a movable platen position detecting means, storage means for storing position information of a movable platen at the time of mold closing in the previous molding cycle, and movable platen at the time of mold closing between two molding cycles. Incremental limit value setting means for setting a limit value of the position difference between the position and the difference between the position of the movable platen at the time of mold closing in the current molding cycle and the position stored in the storage means, and the calculation result It includes a calculation and comparison means for comparing with the limit value, and performing a mold clamping operation on condition that the calculation result does not exceed the limit value (claim 1).

  In Patent Document 2, a set pressure value in a low-pressure mold clamping stroke section is measured at the time of a low-pressure mold clamping stroke in a state where no foreign matter exists between the fixed mold and the movable mold (normal state). It is described that the machine itself automatically corrects the value to the same level as the peak value of the tightening pressure or slightly higher than the peak value (claim 1).

  In Patent Document 3, the set value of the low-pressure mold clamping force is moved toward the fixed mold by adding the mold clamping force of a predetermined magnitude and the mold clamping force of the predetermined magnitude to the movable mold. Sometimes it is calculated based on the correlation with the position where the movable mold is stopped (claim 1), and in the paragraph 0048, the value of the mold clamping force is increased. Then, the mold stop position approaches the position where the movable mold comes into contact with the fixed mold, but when the value of the mold clamping force exceeds a certain value, the mold stop position no longer changes. This position corresponds to the inflection point on the graph, and since it can be determined that the movable mold is in contact with the fixed mold, the value of the mold clamping force corresponding to the inflection point is set to the low pressure mold clamping force. There is a description that the movable mold can be reliably brought into contact with the fixed mold.

Japanese Examined Patent Publication No. 7-121529 Japanese Patent No. 3648059 Japanese Patent No. 4687559

  As described above, the shorter the molding cycle time, the higher the productivity. Therefore, in the manufacturing process, it is necessary to manage the mold closing time so as not to be longer than necessary. In addition, the mold closing time is an important factor in shortening the time for calculating the control upper limit torque.

  However, in any of the methods described in Patent Documents 1 to 3, there is no description that the mold closing time is taken into account when calculating the control upper limit torque. As a known method for calculating the control upper limit torque safely and accurately, there is a method of increasing the torque little by little and repeating the mold closing, but there is a problem that the mold closing time becomes longer than necessary.

Therefore, the inventor of the present application pays attention to the fact that there is a certain relationship between the control upper limit torque and the mold closing time, and comparatively observes the work of a skilled worker (operator) and the work of a new and unskilled worker. As a result, the following was found. Skilled workers seemed to calculate the control upper limit torque so that productivity did not decrease so much. However, new and unfamiliar workers were closing the mold as little as possible. As a result, the mold closing time tends to become longer and the mold closing torque tends to become smaller, the calculation time of the control upper limit torque becomes longer, and the molding cycle time becomes longer.

  That is, the control upper limit torque tends to be smaller as the mold closing time becomes longer, the control upper limit torque tends to be insufficient when the mold closing time is too long, and the control upper limit torque becomes larger as the mold closing time becomes shorter. It has been found that there is a possibility that the control upper limit torque may become excessive if the mold closing time is too short. Therefore, the present inventor has come to the idea that not only the torque but also the mold closing time should be fed back in order to optimize the control upper limit torque of the mold opening / closing control in mold protection.

  That is, since the known automatic calculation method of the control upper limit torque of mold opening / closing control in mold protection is calculated by paying attention only to the control upper limit torque, the mold closing time tends to be longer and the control upper limit torque tends to be smaller. In addition, the time for calculating the control upper limit torque is also long. And it has the problem that productivity will fall because mold closing time becomes longer than needed.

  Accordingly, an object of the present invention is to pay attention to the fact that there is a fixed relationship between the control upper limit torque and the mold closing time, and automatically calculate the control upper limit torque within an appropriate range. It is to provide a calculation method.

  The mold protection set value automatic calculation method of an injection molding machine according to the present invention automatically calculates a control upper limit torque of a driving device in mold opening / closing control in an injection molding machine that performs mold opening / closing control of a movable mold and a fixed mold by a control means. This is a method of closing the mold at the initial torque setting value and actually measuring the initial mold closing time, then measuring the latest mold closing time by closing the mold with the latest torque that is half the previous torque, and closing the previous mold. Repeat the process of measuring the latest mold closing time by closing the mold with the latest torque obtained by halving the previous torque until the latest mold closing time increases at a rate of more than 10% based on time, When the difference between the rated output ratio of the previous torque and the latest torque is within 3%, and the condition that the latest mold closing time increases at a rate of within 10% when the initial mold closing time is used as a reference, the latest torque Is multiplied by a predetermined coefficient and If the condition is not satisfied, repeat the process of closing the mold with the latest torque increased within the range of 1% to 3% of the rated output ratio of the previous torque and measuring the latest mold closing time to update the latest conditions The control upper limit torque of the mold opening / closing control is determined by automatically searching for torque and multiplying the searched latest torque by a predetermined coefficient.

  According to the present invention, it is possible to determine the boundary of the control upper limit torque and improve the accuracy of the boundary determination of the control upper limit torque. Furthermore, since the mold opening / closing operation is performed within a range obtained by multiplying the calculated control upper limit torque by a predetermined coefficient, a safer and more stable mold opening / closing operation is performed.

  In the present invention, the torque is displayed in% at a rate when the rated output of the driving device of the mold opening / closing unit is 100%. The reference mold closing time in the present invention is the time required to perform mold closing from the mold opening limit position to the mold closing limit position at the upper limit torque initial setting value. The upper limit torque in the present invention is displayed as a ratio when the rated output of the driving device of the mold opening / closing unit is 100%.

  The present invention is characterized in that the initial torque setting value is 20% or more and 35% or less.

  According to the present invention, the number of searches for finding the control upper limit torque can be reduced to a necessary limit. Moreover, there is no risk of damage to the mold.

  In the present invention, the initial torque setting value is preferably 35%. This is because the number of searches for finding the control upper limit torque is minimized and there is no risk of damage to the mold.

  The present invention is characterized in that a calculation degree is selected and input by a touch panel provided in the injection molding machine, and the predetermined coefficient is multiplied according to the selected calculation degree.

  According to the present invention, it is possible to prevent an input error in the calculation degree and to make a rational selection by selecting a predetermined number of options. There are a plurality of options for the calculation degree, and it is particularly preferable to display a selection button of three stages. In the case of injection molding, it is considered as a simple and appropriate option to set the calculation degree by classifying small parts, general parts, and large parts.

  The injection molding machine of the present invention is characterized in that the method for automatically calculating the mold protection set value is made to function.

  According to the present invention, even if it is a new worker or an unfamiliar worker, the control upper limit torque in an appropriate range is automatically calculated, so that the injection molding machine is easy to use.

  In the present invention, it is preferable to selectively input whether or not to activate the automatic mold protection function on the touch panel.

  According to the present invention, a skilled worker, a new worker or an unfamiliar worker can select and input whether or not to activate the automatic mold protection function. In addition, since it is possible to selectively input whether or not to activate the automatic mold protection function in the trial operation in the apparatus and mold maintenance and the operation in the production process, the usability is further improved.

  According to the mold protection set value automatic calculation method for an injection molding machine of the present invention, the control upper limit torque of the drive device in safe and necessary and sufficient mold opening / closing control can be set more efficiently and easily. The torque when the torque is halved from the initial set value is a safe value. When the mold closing time increases by more than 10% between the previous torque and the latest torque, a safe control upper limit torque can be determined by the latest torque at the time of mold closing. Next, the actual mold closing time does not change while increasing the output of the driving device by several percent, but the required control upper limit torque of the driving device in the mold opening / closing control is obtained without further increasing the output of the driving device. Therefore, the control upper limit torque of the driving device in the necessary and sufficient desirable mold opening / closing control can be obtained. Furthermore, since the mold opening / closing operation is performed within a range obtained by multiplying the calculated control upper limit torque by a predetermined coefficient, a safer and more stable mold opening / closing operation is performed.

  According to the present invention, the number of searches for finding the control torque can be reduced as much as necessary. Moreover, there is no risk of damage to the mold. And according to this invention, while being able to prevent the input mistake of a calculation degree, rational selection can be performed by selecting a predetermined number of choices.

  According to the present invention, even if the worker is a new worker or an unfamiliar worker, the control upper limit torque in an appropriate range is automatically calculated, so that the injection molding machine is easy to use.

It is a figure which shows the touchscreen screen in the injection molding machine with an automatic metal mold | die protection function of this invention. It is a figure which shows the touchscreen screen in the said injection molding machine. It is a figure which shows the touchscreen screen in the said injection molding machine. It is a figure which shows the touchscreen screen in the said injection molding machine. It is a figure which shows the touchscreen screen in the said injection molding machine. It is a flowchart figure which shows the automatic calculation procedure of the metal mold | die protection setting value in the injection molding machine of this invention. It is a graph which shows the relationship between the torque in the said injection molding machine, and metal mold | die protection setting. It is a structural diagram which shows the principal part of the said injection molding machine.

  Specific embodiments to which the present invention is applied will be described below with reference to the drawings.

(Embodiment of the present invention)
FIG. 8 is a structural diagram showing the injection molding machine with an automatic mold protection function of the present invention from the side surface side. The injection molding machine 100 with an automatic mold protection function of the present embodiment includes a control circuit 107 that performs mold opening / closing control of the movable mold 220 and the fixed mold 210, and the control circuit 107 includes a torque addition ratio with respect to a reference torque. An automatic mold protection function that automatically calculates the upper limit control torque that is the upper limit value is provided. A touch panel 108 for displaying various condition inputs and results is provided (FIG. 8). Note that, in the injection molding machine of this embodiment, the reference torque has data suitable in advance corresponding to the above various conditions based on a number of tests as data, and is initial when the above various conditions are given. Set as set torque.

  The example shown in FIG. 8 is a mold opening / closing unit having a horizontal clamping structure. The mold 200 has a fixed mold 210 and a movable mold 220 facing each other. The fixed mold 210 is attached to a fixed platen (fixed platen) 111 by a clamp means 115, and the movable mold 220 is fixed by a clamp means 116. A movable platen (movable platen) 113 is attached. The fixed platen 111 and the back platen 117 (support plate) are respectively fixed on the machine base 102, and the movable platen 113 is slidable in the horizontal direction via the slide means 190 including the guide member 191 and the rail member 192. It is arranged on the machine base 102. A movable platen 113 is disposed between the fixed platen 111 and the back platen 117, and a plurality of tie bars 110 fixed by the fixed platen 111 and the back platen 117 are inserted through the movable platen 113, and the movable platen 113 is inserted. Is configured to be slidable between the fixed platen 111 and the back platen 117 (FIG. 8). The fixed mold 210 is provided with a locating ring on the back surface (the back surface of the fixed mounting plate), and the locating ring is inserted into a locating ring mounting hole formed in the fixed platen 111 and is injected. The injection nozzle 103a of the unit 103 is inserted into the locating ring 121 and abuts against a sprue bush (not shown) of the fixed mold 210 (FIG. 8). In the example shown in FIG. 8, the movable platen 113 slides to the right by the mold clamping shaft 114a that moves forward and backward by the drive device 114 of the mold opening / closing unit to perform the mold closing operation and the mold clamping operation, and the movable platen 113 slides to the left. Open the mold. A servo motor is applied to the driving device 114.

  FIG. 7 is a graph showing the relationship between torque and mold protection setting in the injection molding machine 100. The mold closing time is the time required to close the mold after the mold opened to the mold opening limit position is closed and to clamp the mold to the mold closing position. The reference mold closing time is required to perform mold closing from the mold opening limit position to the mold closing position at the initial torque setting value on the first shot at the start of the molding cycle or on the first shot after changing the mold opening / closing setting. It was time. The upper limit torque in the present embodiment is displayed as a ratio when the rated output of the servo motor of the driving device 114 in the mold opening / closing unit is 100%.

  In the present invention, the control upper limit torque of the driving device in the mold opening / closing control is automatically searched, and the calculated control upper limit torque is multiplied by a predetermined coefficient to obtain the control upper limit torque in the mold opening / closing control. The control upper limit torque is a power limiter. In the injection molding machine of the embodiment, the monitoring torque is set as shown in FIG. The monitoring torque is a safe torque when the mold is closed and is set to a value lower than the control upper limit torque, and is set so as to stop urgently when the monitoring torque is exceeded.

(Automatic calculation procedure of mold protection setting value of the present invention)
FIG. 6 is a flowchart showing a procedure for automatically calculating the mold protection set value in the injection molding machine of the present invention. 1-5 is a figure which shows the touchscreen screen in the said injection molding machine, and becomes a figure which changed the screen in order from FIG. The automatic calculation procedure of the mold protection set value by the method of the present invention will be described below.

  First, the injection molding machine 100 is activated and the touch panel 108 is operated to display a mold protection menu (FIG. 1). Then, the automatic mold protection switch B1 is set to “ON” (reference S1, FIG. 1). Next, the calculation degree is selected from three switches B2 of “low”, “medium”, and “high” (reference S2, FIG. 1).

  When the calculation degree is selected and input on the touch panel 108, an overall value (clamping start position) is set according to the selected calculation degree. Here, the overall value is the mold clamping start position, and indicates the distance from the zero point. As will be described later, the control upper limit torque is determined by multiplying the automatically searched upper limit torque by a predetermined coefficient according to the selected calculation degree.

For example, if the calculation degree is “low”, the overall value is set to 0.4 mm.
For example, when the calculation degree is “medium”, the overall value is set to 0.3 mm.
For example, if the calculation degree is “high”, the overall value is set to 0.2 mm.

When the calculation degree is set to “low”, the mold clamping start position (overall value) increases, so that it becomes insensitive to mold temperature change. Since the necessary frequency of mold thickness adjustment again until it becomes stable after continuous molding becomes extremely small, it is suitable for molding large parts.
When the calculation degree is set to “medium”, it is a general setting. Occasionally, the mold thickness may need to be adjusted again due to the influence of the mold temperature change.
When the calculation degree is set to “high”, the mold clamping start position (overall value) becomes small, so that it becomes sensitive to the mold temperature change. Although it is necessary to adjust the mold thickness again until it becomes stable after continuous molding, it is suitable for molding small parts.

  The protection time is, for example, actual mold closing time + 0.2 seconds. The initial value of the protection time is, for example, 10 seconds.

For example, when the calculation degree is “low”, the offset value is set to 10.0%.
For example, when the calculation degree is “medium”, the offset value is set to 5.0%.
For example, when the calculation degree is “high”, the offset value is set to 2.0%.

  The calculation degree is selected from three switches of “low”, “medium”, and “high” (reference S2, FIG. 1). In FIG. 1, the calculation degree is set to “high”. When the fully automatic button on the touch panel 108 is pressed and the mold closing button is pressed, the automatic mold function starts. In consideration of the case where the start position is not the mold opening limit position, the mold opening / closing operation is performed twice (reference S3). The mold is closed at the initial torque setting value P41, and the initial mold closing time T1 is measured (reference S3).

  In the present invention, the initial torque setting value P41 is set to 20% or more and 35% or less of the rated output of the driving device. Hereinafter, in the present invention, the ratio of the output to the rated output of the drive device is referred to as the rated output ratio regardless of whether the percentage is expressed as a percentage. In this embodiment, the torque initial set value P41 is set to 35.0% as the rated output ratio of the drive device (FIG. 1). This is because the number of searches for finding the control upper limit torque is minimized and there is no risk of damage to the mold. The following description is based on the numerical values in the screen transition diagrams of the touch panel 108 shown in FIGS.

  In FIG. 1, the mold was closed when the torque initial setting value P41 was 35.0%, and the actually measured initial mold closing time T1 was 0.85 seconds (reference S3).

  Since the initial mold closing time T1 is obtained (reference S3), the mold is closed with the latest torque obtained by halving the previous torque, and the latest mold closing time is actually measured (reference S4).

  The latest torque P42 obtained by halving the previous torque P41 is 35.0% / 2 = 17.5% (FIG. 2). In FIG. 2, the mold was closed at the latest torque P42 of 17.5%, and as a result, the latest mold closing time T2 measured was 0.86 seconds.

  Since the latest mold closing time T2 is obtained (reference S4), it is next determined whether or not the condition that the latest mold closing time is increased at a rate exceeding 10% when the previous mold closing time is used as a reference is satisfied. Judgment is made (reference S5). When the condition of code S5 is satisfied, the process proceeds to step S6, and when the condition of code S5 is not satisfied, the process returns to step S4.

  In FIG. 2, since the latest mold closing time T2 is 0.86 seconds, it does not increase at a rate exceeding 10% based on the previous mold closing time T1 (0.85 seconds in FIG. 1). Is not satisfied, the process returns to step S4.

In FIG. 2, since the condition of the code S5 is not satisfied, the process returns to the step of the code S4. The latest torque P43 obtained by halving the previous torque P42 is 17.5% / 2 = 8.8% (FIG. 3). Here, for the convenience of display, it is rounded off to the second decimal place. Note that the second decimal place may be rounded up and displayed, and the second decimal place may be rounded down.
In FIG. 3, the mold was closed when the latest torque P43 was 8.8%, and as a result, the measured latest mold closing time T3 was 1.01 seconds.

  Next to the step S4, it is determined whether or not the condition S5 is satisfied. In FIG. 3, since the latest mold closing time T3 is 1.01 seconds, it increases at a rate of more than 10% with reference to the previous mold closing time T1 (0.86 seconds in FIG. 2). Since it satisfy | filled, it progresses to the step of code | symbol S6.

  In FIG. 3, since the condition of symbol S5 is satisfied, the difference between the rated output ratio of the previous torque and the latest torque is within 3%, and the latest mold closing time is 10% when the initial mold closing time is used as a reference. It is determined whether or not a condition for increasing at a rate within the range is satisfied (reference S6). When the condition of code S6 is satisfied, the process proceeds to step S8, and when the condition of code S6 is not satisfied, the process proceeds to step S7.

  In FIG. 3, since the difference of the rated output ratio of the latest torque P43 with respect to the previous torque P42 is 17.5% −8.8% = 8.7%, the condition of the sign S6 is not satisfied. Proceed to

In FIG. 3, since the condition of symbol S6 is not satisfied, the mold is closed with the latest torque obtained by increasing the previous torque by 3%, and the latest mold closing time is actually measured (sign S7). The latest torque P44 obtained by increasing the previous torque P43 by 3% is 8.8% + 3.0% = 11.8% (FIG. 4). Here, for the convenience of display, it is rounded off to the second decimal place.
In FIG. 4, the mold was closed at the latest torque P44 of 11.8%, and as a result, the measured latest mold closing time T4 was 0.88 seconds.

  After step S7, it is determined whether or not the condition of code S6 is satisfied (code S6). In FIG. 4, the difference in the rated output ratio of the latest torque P44 relative to the previous torque P43 is within 3%. In addition, since the latest mold closing time T4 increases at a rate within 10% when the initial mold closing time T1 (0.85 seconds in FIG. 1) is used as a reference, the condition of symbol S6 is satisfied. The process proceeds to step S8.

  In FIG. 4, since the condition of the symbol S6 is satisfied, the control upper limit torque of the mold opening / closing control is determined by multiplying the searched latest torque by a predetermined coefficient (reference S8).

For example, when the calculation degree is “low”, the searched latest torque is multiplied by 2.0 to obtain the control upper limit torque of the mold opening / closing control.
For example, when the calculation degree is “medium”, the searched latest torque is multiplied by 1.5 to obtain the control upper limit torque of the mold opening / closing control.
For example, when the calculation degree is “high”, the searched latest torque is multiplied by 1.2 to obtain the control upper limit torque of the mold opening / closing control.

  In FIG. 1, since the calculation degree is set to “high”, the searched latest torque P44 is multiplied by 1.2 to obtain the control upper limit torque P45 of the mold opening / closing control (reference S8). That is, the control upper limit torque P45 of the mold opening / closing control obtained by multiplying the searched latest torque P44 by 1.2 is 11.8% × 1.2 = 14.2% (FIG. 5). Here, for the convenience of display, it is rounded off to the second decimal place.

  According to the present embodiment, the boundary determination of the control upper limit torque is made, and the accuracy of the boundary determination is improved. Furthermore, since the mold opening / closing operation is performed with the control upper limit torque obtained by multiplying the calculated upper limit torque by a predetermined coefficient, a safer and more stable mold opening / closing operation can be performed.

  As described above, the present invention is not limited to the embodiment described above. Each item of mold protection can be changed to any value. Thus, it goes without saying that the present invention can be modified as appropriate without departing from the spirit of the present invention.

100 Injection molding machine with automatic mold protection function,
107 control means (control circuit),
108 touch panel,
200 mold (movable mold and fixed mold),
210 fixed type,
220 Movable type,
P41 Initial torque setting value, previous torque,
P42, P43, P44 Latest torque,
Control upper limit torque of P45 type opening / closing control,
T1 initial mold closing time,
T2, T3, T4 Latest mold closing time

Claims (5)

  In an injection molding machine that performs mold opening / closing control of a movable mold and a fixed mold by a control means, this is a method of automatically calculating the control upper limit torque of the drive unit in mold opening / closing control. Measure the time, then measure the latest mold closing time by closing the mold with the latest torque halved from the previous torque, and the latest mold closing time when the previous mold closing time is used as a reference is over 10% Repeat the process of measuring the latest mold closing time by closing the mold with the latest torque, which is half the previous torque until it increases in proportion, and then the difference in rated output ratio between the previous torque and the latest torque is within 3% And when satisfying the condition that the latest mold closing time increases at a rate within 10% when the initial mold closing time is used as a reference, the latest torque is multiplied by a predetermined coefficient, and when the condition is not satisfied, 1 of rated output ratio of torque The process of measuring the latest mold closing time by closing the mold with the latest torque increased in the range of 3% or less above is repeated to automatically search for the latest torque satisfying the above conditions, and multiply the searched latest torque by a predetermined coefficient. A mold protection set value automatic calculation method for an injection molding machine, characterized in that the control upper limit torque of mold opening / closing control is determined.   2. The mold protection set value automatic calculation method for an injection molding machine according to claim 1, wherein the initial torque set value is 20% or more and 35% or less.   2. The mold protection set value automatic calculation method for an injection molding machine according to claim 1, wherein the initial torque set value is 35%.   The injection according to any one of claims 1 to 3, wherein a calculation degree is selected and input by a touch panel provided in the injection molding machine, and the predetermined coefficient is multiplied according to the selected and calculated calculation degree. Mold protection setting automatic calculation method for molding machines.   An injection molding machine characterized by causing the mold protection set value automatic calculation method according to any one of claims 1 to 4 to function.

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