JPH0471766A - Method for controlling die clamping force in die casting machine - Google Patents

Abstract

PURPOSE:To carefully control die clamping force by measuring the die clamping force, comparing with the preset value, calculating the average value in the prescribed times at the time of exceeding the permissible range and correcting the deviation quantity to correct the die clamping force. CONSTITUTION:The die clamping is executed with the block 4 and extension of a tie bar is detected with the block 5 and operation is executed with the block 6 to obtain the die clamping force. This is compared with the preset value with the block 8 and in the case of being in the permissible range, casting is executed. In the case of being out of the permissible range, it is judged whether the die clamping force data are the prescribed times or not, with the block 11. Generally, three - four times are good. The average value and the deviation value are obtd. with the blocks 12, 13 are after casting, adjustment of the preset value is executed with the block 16. As the judgement of die clamping force correction is executed at each casting, always this can be kept to in the permissible range and quality control of the casting is sufficiently executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold clamping force control method for a toggle link type die casting machine.

[Prior Art] The mold clamping force of a toggle link die-casting machine changes as the mold thickness changes due to a change in mold temperature during operation of the die-casting machine. When the mold temperature rises, the mold clamping force may increase due to thermal expansion of the mold, or a situation may occur where the mold cannot be clamped. On the other hand, when the mold temperature decreases, the mold contracts and the mold clamping force decreases. In order to prevent this, appropriate mold clamping force control is required.

Conventionally, the mold clamping force of a toggle link type dice card machine is controlled by a die height device. To adjust the mold clamping force, the mold clamping force is determined by detecting changes in the elongation of the tie bars with a measuring device, etc., and the casting operator constantly monitors this, and if an abnormality is discovered, the casting operation is stopped. The adjustment was made by rotating the tie bar nut and adjusting the die height device, which required a lot of time and manpower. Therefore, from the viewpoint of speeding up this adjustment work and saving labor, a tie bar elongation detector, a die height device, and a microcomputer are combined to automatically adjust the die height device and control the mold clamping force of the toggle type die casting machine. method has been adopted. Regarding this automatic mold clamping force control method for a toggle link type die casting machine, there is, for example, Japanese Patent Publication No. 5G-55860.

[Problems to be Solved by the Invention] A type of toggle link type die casting machine that combines a conventional tie bar elongation detector, die height device, and microcomputer, such as the mold clamping force control method disclosed in Japanese Patent Publication No. 58-55860 mentioned above. The clamping force control method uses a control method that immediately corrects the mold clamping force when the measured value of the mold clamping force falls outside of the allowable range value, which is the standard for determining whether or not to correct the mold clamping force. Some methods employ a control method in which the mold clamping force is corrected when the actual value of the mold clamping force exceeds the allowable range value a predetermined number of times in succession.

In such conventional mold clamping force control methods, in the case of the former control method in which the mold clamping force is immediately corrected when the actual measured value deviates from the allowable range value even once, the mold clamping force is corrected immediately during operation of the toggle link type die casting machine. The actual value of the clamping force may be within the allowable range due to sudden fluctuations, such as foreign objects caught between the stationary mold and the movable mold, rather than changes in the mold clamping force due to changes in mold thickness due to temperature changes. Since the mold clamping force is corrected even if it deviates from the above, there is a strong possibility that the correction will be made even though it should not be corrected, resulting in excessive correction. This is not a desirable control method from the viewpoint of protection of the mold and work safety, but is a problem with automatic mold clamping force control methods. In addition, in the case of the latter control method in which correction is made only when the actual mold clamping force value deviates from the allowable range value a predetermined number of times in a row, overcorrection due to the aforementioned sudden fluctuation factors can be prevented, but the correction This caused the inconvenience that the mold clamping force could not be properly controlled due to the delay.

Incidentally, the temperature increase in a die-casting mold is generally caused by heat transfer from the molten metal to the mold. If the temperature of the mold rises too much, the molten metal may seize the mold, and it takes time to cool the cast product, which increases cycle time, reduces productivity, changes the solidification state, and causes shrinkage. A nest may occur. For this reason, the mold is cooled externally by passing cooling water into the mold or by spraying a cooling liquid (generally also used as a mold release agent in many cases) directly onto the mold surface. Therefore, thermal expansion of the mold occurs during the casting cycle from a low mold temperature at the beginning of casting to an appropriate mold temperature.

b. When the cycle time is shortened (especially likely to occur when not fully automatic operation).

When the temperature of the molten metal rises when replenishing the molten metal to the C1 holding furnace.

d. When the supply and demand balance of coolant changes and the amount of coolant decreases.

e. When the cooling liquid decreases due to clogging of the nozzle of the mold's 4-cooling device.

f. When the amount of cooling liquid is decreased to increase the mold temperature.

Furthermore, shrinkage of the mold due to heat occurs under the following conditions.

a. When cycle time is increased.

b. When the temperature of the molten metal drops when replenishing the molten metal to the holding furnace.

When the supply and demand balance of C1 coolant fluctuates and the amount of coolant increases.

d. When the nozzle clogging of the mold's 4-cooling device is cleared.

e. If there is a crack in the mold, the movement of the moving core installed in the mold is poor, or the product cannot be extruded completely, we will temporarily stop casting to correct this. When the mold temperature drops during the interruption.

f. When the amount of cooling liquid was increased because the mold temperature rose too much.

In addition to the above-mentioned expansion and contraction due to the temperature of the mold, the mold clamping force changes due to the following factors.

a. When a foreign object gets caught between the molds.

b. When the mold is filled with molten metal, if paris occurs, the actual casting area increases and the mold opening force during casting increases.
The measured mold clamping force increases.

C1 Generally, the mold clamping force is determined by directly detecting the elongation of the tie bar, but errors in the measurement of the mold clamping force may rarely occur due to mechanical malfunctions of moving parts such as springs of the detection device.

Therefore, when correcting the mold clamping force, it is necessary to take into account that various steady and unsteady factors that affect the variation of the mold clamping force as described above may occur singly or multiple phenomena may occur simultaneously. It is important to correct the mold clamping force with good sensitivity and without overcorrecting.

The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to prevent the mold clamping force from changing due to mold temperature changes in a method for automatically controlling the mold clamping force of a toggle link type die casting machine. In addition to changes in mold clamping force caused by changes in thickness, for example, changes in mold clamping force caused by foreign objects such as burrs or flash during casting should be avoided as much as possible, and the mold When correcting the clamping force, if the actual value of the mold clamping force deviates from the actual value, calculate the deviation amount between the set value and the average value of the mold clamping force data stored in the buffer for a predetermined number of times, including the actual value. By correcting the mold clamping force by correcting the amount of deviation, the mold clamping force can be automatically controlled quickly and with little error in response to changes in the mold clamping force. As a result, it is possible to improve the product yield during fully automatic operation of the die-casting machine and ensure the safety of the casting operation.

[Means for Solving the Problems] In order to achieve the above object, the mold clamping force control method for a toggle link type die casting machine according to the present invention measures mold clamping force, and combines the measured value with a predetermined mold clamping force. If the measured value exceeds the upper and lower allowable ranges that are used as the basis for determining whether or not to correct the mold clamping force, the measured value that exceeds the allowable range will be included. The method calculates the average value of consecutive predetermined mold clamping times, and corrects the deviation amount between this average value and the set value to correct the mold clamping amount so that the mold clamping force is within the allowable range. be.

If the measured value exceeds the allowable range immediately after starting operation or immediately after correcting the mold clamping force, and before reaching the specified number of mold clamping times, the value will be corrected using the average measured value of the number of mold clamping times after starting operation or after correction. The mold clamping force is controlled by correcting the clamping amount of the mold appropriately.

[Operation] The mold clamping force control method of the present invention configured as described above measures the mold clamping force at the time when the casting cycle of the die casting machine is started and the mold is clamped, calculates the mold clamping force, and calculates the mold clamping force. After storing the value in the buffer, it is determined whether the measured mold clamping force exceeds the tolerance range that is the criterion for mold clamping force correction, and if it exceeds it, it is stored in the buffer. Processing is performed to obtain the average value of the mold clamping force data for a predetermined number of times. Then, this average value is compared with the set value, and the die height device is adjusted to correct the amount of deviation, thereby controlling the mold clamping force of the toggle link type die casting machine. If the mold clamping force data stored in the buffer is not enough for a predetermined number of times, calculate the average value using only the data stored in the buffer at that time, and calculate the deviation between this average value and the set value. It works in the same way as above.

[Example] To explain the example based on the flowchart of the drawing, after setting the mold clamping force in block 1 in the drawing,
After clearing the buffer in block 2, the cycle of the control method of the present invention starts in block 3, and mold clamping is performed in block 4.

Next, in block 5, the elongation of the tie bars during mold clamping is detected. In block 6, the mold clamping force is calculated from the measured values of the blocks. In block 7, the mold clamping force data obtained by the calculation in block 6 is stored in a buffer. Next, in block 8, the mold clamping force stored in the buffer is within the predetermined mold clamping force set value, that is, the upper and lower limit tolerance ranges for determining whether or not to correct the mold clamping force. Compare and judge whether or not. The result of the comparative judgment in this block 8 is YES.
When , that is, if the mold clamping force is within the allowable range of the set value, the process proceeds directly to block 9, where casting is performed, the mold is opened in block 10, and then returns immediately after the start to block. The mold clamping in step 4 is performed, and the same process as described above is performed. On the other hand, if the result of the comparative judgment in block 8 is NO, that is, if the currently measured mold clamping force stored in the buffer is outside the allowable upper and lower limits, the process proceeds to block 11, where further processing is performed. It is determined whether the mold clamping force data stored in the buffer including the measured mold clamping force value exceeds a predetermined number of times.

The predetermined number of times in this case depends on the usage conditions of the die-casting machine in the foundry, but the inventor has confirmed that good correction can generally be made about 3 to 4 times.

If this predetermined number of times is too large, it is effective when the mold clamping force fluctuates due to sudden factors or when the mold clamping force fluctuates due to various fluctuation factors occurring or disappearing. However, if the mold clamping force fluctuates only due to stationary factors, the amount of correction will be small and convergence to the set value will tend to be slow.

On the other hand, if this predetermined number of times is small, it may be effective if the mold clamping force fluctuates only due to steady factors, or if the mold clamping force fluctuates due to sudden factors or various fluctuation factors. If the mold clamping force fluctuates due to the appearance or disappearance of the mold, there is a tendency for over-correction.

Here, if it is determined that the mold clamping force is equal to or more than the predetermined number of times, in the next block 12, the average value of the mold clamping force for the predetermined number of times is determined by going back and including the value of the mold clamping force measured this time. That is, it counts from the mold clamping force data stored in the buffer last, extracts a predetermined number of times, and calculates the average value. The average value of the mold clamping force determined in block 12 is compared with the set value in block 13 to determine the amount of deviation between the two. and block 1
After casting is performed in step 4, the mold is opened in block 15, and the die height is adjusted in block 16 to correct the mold clamping force by the amount of deviation obtained in block 13 so that the deviation between the average value and the set value is eliminated. The device is calibrated. Thereafter, in block 17, the mold clamping force data stored in the buffer is cleared.

On the other hand, if it is determined in block 11 that the mold clamping force data stored in the buffer including the mold clamping force measured this time does not exceed the predetermined number of times, the process advances to block 18 and the data is stored in the buffer. The average value is calculated by including the mold clamping force data of only the number of times and the mold clamping force data measured this time. Then, in block 13, the determined average value of the mold clamping force and the set value are compared to determine the amount of deviation between the two. Thereafter, the processing proceeds to block 14, block 15, block 16, and block 17 in the same manner as described above.

[Effects of the Invention] As described above, the mold clamping force control method for a toggle link type die casting machine according to the present invention automatically corrects the mold clamping force to a predetermined value by the processing procedure explained in the embodiment, and furthermore, this processing Since the procedure is repeated according to the casting cycle, the required mold clamping force can be maintained within the set range at all times. In particular, in order to prevent excessive correction, if the tolerance range that is used as the criterion for mold clamping force correction is exceeded, correction is performed for each casting. The product yield is improved because the correction is performed more quickly than when the correction is made when the deviation is outside the permissible range. In addition, since the correction is to correct the deviation amount between the average value and the set value for a predetermined number of times of the mold clamping force data stored in the buffer, it is possible to control the mold clamping force in a fine grained manner, thereby improving the quality of the cast product. It has the effect of ensuring sufficient management.

FIG.

Applicant's agent: Patent attorney Takehiko Suzue

Claims (1)

[Claims] 1. A mold clamping force control method for a toggle link die casting machine that uses a die height device to automatically adjust the clamping force of a mold, in which the clamping force is measured; The value is compared with a predetermined mold clamping force setting value, and when the measured value exceeds the upper and lower tolerance ranges, it is determined whether or not to correct the mold clamping force. The clamping force of the mold is calculated by calculating the average value of the continuous predetermined number of mold clamping times, including the measured value, and adjusting the deviation amount between this average value and the set value so that the clamping force is within the allowable range. A mold clamping force control method for a toggle link type die casting machine, which is characterized by correcting. 2.Claim 1: If the permissible range is exceeded after the start of operation or before reaching the predetermined number of times of mold clamping after correction, the correction is made using the average measured value of the number of times of mold clamping after the start of operation or after correction.
A mold clamping force control method for a toggle link die-casting machine as described in .