JP4066557B2 - Casting method - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a casting method such as die casting .
[0002]
[Prior art]
In recent years, cast products such as die cast parts have been required to have a near net shape that is closer to the final shape in order to reduce the number of cutting operations in post-processing.
On the other hand, cast products are generally shaped in advance in consideration of draft in order to facilitate product release or core removal from the product.
[0003]
For example, when a cylindrical hollow portion is provided inside a product, the shape of the core is usually provided so that the outer diameter gradually increases in the direction in which the core is removed.
In such a case, in order to realize the near net shaping, it is necessary to make the draft as small as possible.
However, when the draft angle of the hollow portion (the core punched portion) is reduced, the releasing force when the core is removed from the product is greatly increased. In addition, due to the increase in the releasing force, the product may be seized into the mold at the time of releasing.
[0004]
Therefore, the applicant, as shown in Japanese Patent Application No. 10-105812, determines the timing for casting the slide core, and the timing for opening the pair of molds after the molten metal around the slide core is solidified. A method before this was proposed earlier. As a result, the cast product weakens the force that restrains the slide core to prevent the release force from increasing, and the cast product having a hollow portion can be made into a near net shape.
[0005]
[Problems to be solved]
However, in the conventional casting method according to the above proposal, the timing of drawing out the slide core is delicate, and it is difficult to completely prevent the occurrence of defects.
That is, if the timing of pulling out the slide core is deviated, there is a possibility that the slide core breaks or that the slide core is cast out in an unsolidified state of the molten metal.
In addition, even if such a problem occurs, it is difficult to determine this at the manufacturing stage, and there is a possibility that a defective product will flow out to the subsequent process.
[0006]
The present invention has been made in view of such conventional problems, and it is intended to provide a casting method that can easily determine the occurrence of a defective product due to a shift in the drawing timing of the slide core and prevent the outflow of the defective product. It is what.
[0007]
[Means for solving problems]
According to a first aspect of the present invention, there is provided a casting apparatus having a pair of molds forming a cavity and a slide core disposed so as to be able to advance and retreat with respect to the cavity. The molten metal is filled into the cavity in a state of entering the inside,
Then, after becoming a temperature above the melt solidifies in the periphery of the slide core reaches the set temperature set in advance after the temperature of the mold or a slide core has peaked, generally the molten metal In a method of casting a cast product having a hollow portion by retracting the slide core from the cavity before the mold opening time of the pair of molds that can be released after solidification is completed ,
The pulling force acting when the slide core is withdrawn from the cavity is measured, the measured value is compared with an appropriate value having a preset upper limit value and lower limit value, and the measured value is the upper limit of the appropriate value. The quality of the cast product with respect to the shape of the hollow portion formed by the slide core is determined by determining whether or not the measured value is smaller than the lower limit value of the appropriate value. It is in the casting method characterized by determining.
[0008]
The most notable aspect of the present invention is that the pulling force acting when the slide core is withdrawn from the cavity is measured, and the measured value is compared with appropriate values having preset upper and lower limits. And determining the quality of the cast product.
[0009]
The quality of the cast product is, for example, the quality of the shape of the hollow portion formed by the slide core.
The time of solidification of the molten metal around the slide core means at least the time when the molten metal located in the cavity portion formed between the slide core and the mold facing the solidified solidified. Therefore, it does not matter whether the molten metal such as the solid part where the slide core is not located is completely solidified.
Further, the mold opening time of the mold means a time when the molten metal is completely solidified to become a cast product and can be released from the mold.
[0010]
Next, the effects of the present invention will be described.
In the casting method of the present invention, as described above, the pulling force acting when the slide core is retracted from the cavity is measured, and the measured value and an appropriate value having a preset upper limit value and lower limit value are obtained. The quality of the cast product is determined by comparison.
That is, when the measured value is at the appropriate value, it is determined that the cast product is non-defective, and when the measured value is not at the appropriate value, it is determined that the cast product is defective.
[0011]
In performing the casting, if the slide core is pulled out of timing, problems such as breakage of the slide core or casting of the slide core in the unsolidified state of the molten metal occur. The cast product cast at this time becomes a defective product.
When such a defect occurs, the quality of the cast product can be determined by comparing the measured value with the appropriate value as described above.
For this reason, it is possible to easily determine the occurrence of a defective product due to a shift in the drawing timing of the slide core, and it is possible to prevent the defective product from flowing out to the subsequent process.
[0012]
As described above, according to the present invention, it is possible to provide a casting method that can easily determine the occurrence of a defective product due to a shift in the drawing timing of the slide core and prevent the defective product from flowing out.
[0013]
Next, as in a second aspect of the present invention, the pulling force of the slide core can be measured by a pressure sensor attached to a hydraulic cylinder that moves the slide core back and forth.
That is, by measuring the hydraulic pressure of the hydraulic cylinder, the pulling force applied when the slide core is pulled out from the cavity can be indirectly measured.
Therefore, the pulling force can be measured easily and accurately.
[0014]
Next, as in the invention described in claim 3, it is preferable to issue an alarm when the measured value of the pulling force is not at the appropriate value.
As a result, the operator can be easily notified of the abnormality, and the outflow of defective products to the next process can be reliably prevented.
[0015]
Next, as in the invention described in claim 4, when the measured value of the pulling force is not the appropriate value, it is preferable to exclude the cast product.
As a result, the outflow of defective products to the next process can be prevented more reliably.
[0016]
Next, as in the invention described in claim 5, it is preferable that the casting apparatus is stopped when the measured value of the pulling force exceeds the upper limit value of the appropriate value.
When the measured value of the pulling force exceeds the upper limit value, there is a high possibility that the slide core is broken. In such a case, if the casting apparatus is continuously operated while the slide core is broken, a large amount of defective products will be cast.
According to the present invention, it is possible to reliably prevent such mass casting of defective products.
Next, as in the invention described in claim 6, the casting apparatus is provided with a hydraulic cylinder for advancing and retracting the slide core, and for measuring the temperature of the mold or the slide core. a temperature sensor, is provided with a control unit for instructing the exit timing of the slide core in the hydraulic cylinder, said control unit, and the measured temperatures T ₁ sent from the set temperature T ₀ and the temperature sensor set in advance And when the measured temperature T ₁ reaches the set temperature T ₀ , the hydraulic cylinder issues a sliding core withdrawal instruction to the hydraulic cylinder, so that the hydraulic cylinder causes the sliding core to retract from the cavity. It is preferable.
Next, as in a seventh aspect of the invention, the mold is clamped to form the cavity, and the slide core is inserted into the cavity, and the melt is filled into the cavity. A step of determining whether or not the actual temperature T ₁ has reached a peak, and determining whether or not the actual temperature T ₁ has reached a set temperature after the peak of the actual temperature T ₁ has been confirmed. It is preferable that the method includes a step of performing the step of removing the slide core after confirming that the measured temperature T ₁ has reached the set temperature T ₀ .
Next, as in the invention described in claim 8, the measured value to be compared with the appropriate value is the maximum value of the measured value of the pulling force that changes for a while from the start to the end of pulling out the slide core. Preferably there is.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments A casting method and a casting apparatus according to embodiments of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the casting method of this example is a casting apparatus 1 having a pair of molds 11 and 12 forming a cavity 2 and a slide core 3 disposed so as to be movable back and forth with respect to the cavity 2. Is used.
[0023]
Then, the molten core 88 is filled into the cavity with the slide core 3 inserted into the cavity 2 (FIG. 1). Next, after the molten metal 88 around the slide core 3 is solidified, the slide core 3 is withdrawn from the cavity 2 before the opening time of the pair of molds 11 and 12.
Thereby, the cylindrical casting 8 having the hollow portion 80 shown in FIG. 2 is cast. The hollow portion 80 is a cylindrical deep recess.
[0024]
In the casting, the pulling force acting when the slide core 3 is retracted from the cavity 2 is measured, and the measured values are compared with appropriate values having preset upper and lower limits. The quality of the casting 8 is determined.
[0025]
Below, the casting apparatus 1 of this example is demonstrated based on FIG.
The casting apparatus 1 is provided with a hydraulic cylinder 30 for moving the slide core 3 back and forth, a temperature sensor 4 for measuring the temperature of the molds 11 and 12 or the slide core 2, and the hydraulic cylinder 30. And a control unit 5 for instructing the exit timing of the slide core 3.
The control unit 5 temperatures T ₁ measurement said actual is compared with the measured temperatures T ₁ sent from the set temperature T ₀ and the temperature sensor set in advance of the slide core 3 at the time when reached the set temperature T ₀ It is configured to issue an exit instruction.
[0026]
As shown in FIG. 1, the pair of molds 11 and 12 is a die casting mold provided with an injection cylinder 15 and an injection plunger 16, and the molten metal 88 introduced into the injection cylinder 15 is caused by the injection plunger 16. The cavity 2 is configured to be pressurized and filled through the gate 17. In the molds 11 and 12, reference numeral 12 in FIG. 1 is a fixed mold, and reference numeral 11 is a movable mold.
[0027]
As shown in FIG. 1, the temperature sensor 4 provided on the mold 12 is constituted by a thermocouple and is embedded in a portion facing the slide core 3. The temperature sensor 4 is electrically connected to the control unit 5, detects the temperature of the mold 12 every moment, and sends the detected value to the control unit 5.
[0028]
As shown in FIG. 1, the slide core 3 extends downward from a hydraulic cylinder 30 provided above the molds 11 and 12, and is advanced and retracted in the vertical direction by the action of the hydraulic cylinder 30. It is provided to do. The hydraulic cylinder 30 is electrically connected to the control unit 5 and is configured to move the slide core 3 forward and backward based on instructions from the control unit 5.
[0029]
As shown in FIG. 1, a pressure sensor 31 for measuring the pulling force of the slide core 3 is attached to the hydraulic cylinder 30. The pressure sensor 31 is electrically connected to the determination unit 6 via the amplifier 32. The casting apparatus 1 has an alarm 61 that emits an alarm sound and an alarm light based on a signal from the determination unit 6.
[0030]
Next, a series of casting operations in this example will be described more specifically with reference to FIGS.
FIG. 3 is a flowchart showing a series of casting operations from mold clamping to mold opening of the molds 11 and 12 in time series. FIG. 4 is an explanatory diagram showing the transition of the measured temperature T ₁ of the mold 12 measured by the temperature sensor 4 with time on the horizontal axis and temperature on the vertical axis.
For convenience of explanation, the times corresponding to the step numbers (S1 to S10) in FIG. 3 are shown using the same numbers in FIG.
[0031]
As shown in FIG. 3, first, in step S <b> 1, the molds 11 and 12 are clamped to form the cavity 2 and the slide core 3 is inserted into the cavity 2. Next, the molten metal 88 is filled into the cavity 2 in step S2. Thus, as shown in FIG. 4, the measured temperature T ₁ of the a mold 12 toward time S1~S2 the cooling process, rapidly increase in temperature molten metal filling (S2) opportunities.
[0032]
Then, the measured temperature T ₁ is to determine whether the peaked at step S3, S4. That is, it is monitored whether or not the actually measured temperature T ₁ that has been heated after filling the molten metal starts cooling.
Next, after the peak of the actually measured temperature T ₁ is confirmed in step S4, it is determined whether or not the actually measured temperature T ₁ has reached the set temperature in steps S5 and S6.
[0033]
Then, after confirming that the actually measured temperature T ₁ has reached the set temperature T ₀ in step S4, the slide core 3 is withdrawn in step S7.
Thus, the slide core 3 can be pulled out from the cast product 8 with a small release force without destroying the solidified state of the molten metal 88 in the cavity 2.
[0034]
At this time, the pulling force of the slide core 3 is measured by measuring the hydraulic pressure of the hydraulic cylinder 30 by the pressure sensor 31 (S8). The measured value is sent to the determination unit 6 through the amplifier 32 (S9).
Thereafter, in step S10, the molds 11 and 12 are opened, and one cycle of a series of casting operations is completed.
[0035]
Further, when the determination unit 6 receives the measurement value sent in step 9 in step P1, as shown in FIG. 5, the determination unit 6 compares the measurement value with the appropriate value to determine the quality of the cast product 8. judge.
That is, in step P2, the measured value is compared with the upper limit value of the appropriate value. And when the said measured value is below the said upper limit, it progresses to step P3.
[0036]
On the other hand, when the measured value is larger than the upper limit value, it is determined that the cast product 8 cast at that time is defective, and the cast product 8 is discharged in step P4. In this case, it is determined that the slide core 3 is broken, the casting apparatus 1 is stopped in step P5, and the alarm device 61 is operated in step P6.
[0037]
In step P3, the measured value is compared with the lower limit value of the appropriate value. And when the said measured value is more than the said lower limit, it judges that casting is performed normally and complete | finishes 1 cycle.
On the other hand, if the measured value is smaller than the lower limit value, it is determined that the cast product 8 cast at that time is defective, and the cast product 8 is discharged in step P7, and the alarm device 61 in step P8. Is activated.
[0038]
The measured value of the pulling force of the slide core 3 changes for a while from the start to the end of pulling as shown by the waveforms H ₁ , H ₂ and H ₃ in FIG. Therefore, as described above, the maximum values K ₁ , K ₂ , and K ₃ are used as the measured values to be compared with the appropriate values.
Therefore, when the waveform of the measured value is the waveform indicated by H ₁ in FIG. 6, it is determined that the slide core 3 is broken. When the waveform of the measured value is a waveform indicated by H ₂ , it is determined that the slide core 3 has been pulled out in an unsolidified state of the molten metal 8. Further, when the waveform of the measurement value is a waveform indicated by H ₃ , the maximum value K ₃ is between the upper limit value and the lower limit value, so that it is determined to be normal.
[0039]
Next, the effect of this example will be described.
In the casting method of this example, as described above, the pulling force acting when the slide core 3 is withdrawn from the cavity 2 is measured, and the measured value and an appropriate value having a preset upper limit value and lower limit value are measured. And the quality of the casting 8 is determined.
[0040]
When performing the above casting, if the slide core 3 is pulled out of timing, the slide core 3 may be broken or the slide core 3 may be cast out when the molten metal 88 is not solidified. appear. The cast product 8 cast at this time becomes a defective product.
When such a problem occurs, as described above, the quality of the cast product 8 can be determined by comparing the measured value with the appropriate value.
Therefore, it is possible to easily determine the occurrence of a defective product due to the deviation of the drawing timing of the slide core 3, and it is possible to prevent the defective product from flowing out to a subsequent process in large quantities.
[0041]
The pulling force of the slide core 3 is measured by a pressure sensor 31 attached to the hydraulic cylinder 30. That is, by measuring the hydraulic pressure of the hydraulic cylinder 30, the pulling force applied when the slide core 3 is pulled out from the cavity 2 can be indirectly measured. Therefore, the pulling force can be measured easily and accurately.
[0042]
Further, since the alarm device 61 is activated when the measured value of the pulling force is not at the appropriate value, it is possible to easily notify the operator of an abnormality and to reliably prevent the outflow of defective products to the next process. it can.
Further, when the measured value of the pulling force is not at the appropriate value, the casting product 8 is excluded, so that the outflow of defective products to the next process can be prevented more reliably.
[0043]
Moreover, since the said casting apparatus 1 stops when the measured value of the said drawing force exceeds the upper limit of the said appropriate value, it can prevent mass casting of inferior goods reliably.
That is, when the measured value of the pulling force exceeds the upper limit value, there is a high possibility that the slide core 3 is broken. In such a case, if the casting apparatus 1 is continuously operated with the slide core 3 broken, a large amount of defective products will be cast.
According to this example, it is possible to reliably prevent such a mass casting of defective products.
[0044]
In the above embodiment, the pulling force of the slide core is measured using a pressure sensor. However, a strain gauge may be embedded in the slide core, and the force acting on the slide core may be directly measured.
[0045]
As described above, according to this example, it is possible to provide a casting method and a casting apparatus that can easily determine the occurrence of a defective product due to a deviation in the drawing timing of the slide core and prevent the defective product from flowing out.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a casting apparatus in an embodiment.
FIG. 2 is a perspective view of a cast product in the embodiment.
FIG. 3 is a flowchart showing a flow of casting work in the embodiment.
FIG. 4 is a diagram showing a change in mold temperature in the embodiment.
FIG. 5 is a flowchart showing a flow of non-defective product determination and subsequent processing in the embodiment.
FIG. 6 is a diagram showing a change in the pulling force of the slide core in the embodiment.
[Explanation of symbols]
1. . . Casting equipment,
11,12. . . Mold,
2. . . cavity,
3. . . Sliding core,
30. . . Hydraulic cylinder,
31. . . Pressure sensor,
5. . . Control unit,
6). . . Judgment part,
61. . . Alarm,
8). . . Castings,
80. . . Hollow part,
88. . . Molten metal,

Claims (8)

Using a casting apparatus having a pair of molds forming a cavity and a slide core disposed so as to be capable of advancing and retreating with respect to the cavity, the cavity is inserted into the cavity. Fill the inside with molten metal,
Then, after becoming a temperature above the melt solidifies in the periphery of the slide core reaches the set temperature set in advance after the temperature of the mold or a slide core has peaked, generally the molten metal In a method of casting a cast product having a hollow portion by retracting the slide core from the cavity before the mold opening time of the pair of molds that can be released after solidification is completed ,
The pulling force acting when the slide core is withdrawn from the cavity is measured, the measured value is compared with an appropriate value having a preset upper limit value and lower limit value, and the measured value is the upper limit of the appropriate value. The quality of the cast product with respect to the shape of the hollow portion formed by the slide core is determined by determining whether or not the measured value is smaller than the lower limit value of the appropriate value. The casting method characterized by determining.   2. The casting method according to claim 1, wherein the pulling force of the slide core is measured by a pressure sensor attached to a hydraulic cylinder for moving the slide core back and forth.   3. The casting method according to claim 1, wherein an alarm is issued when the measured value of the pulling force is not at the appropriate value.   The casting method according to any one of claims 1 to 3, wherein when the measured value of the pulling force is not at the appropriate value, the cast product is excluded.   The casting method according to claim 1, wherein the casting apparatus is stopped when a measured value of the pulling force exceeds an upper limit value of the appropriate value. 6. The temperature sensor according to claim 1, wherein the casting apparatus includes a hydraulic cylinder for moving the slide core forward and backward, and measures the temperature of the mold or the slide core. And a control unit for instructing the withdrawal timing of the slide core to the hydraulic cylinder. The control unit sets a preset temperature (T ₀ ) set in advance and an actually measured temperature (T ₁ ) sent from the temperature sensor. ) And when the measured temperature (T ₁ ) reaches the set temperature (T ₀ ) , the hydraulic cylinder issues a slide core withdrawal instruction to the hydraulic cylinder. A casting method characterized in that the casting is withdrawn from the cavity. 7. The method according to claim 6, wherein the mold is clamped to form the cavity, the slide core is inserted into the cavity, the molten metal is filled into the cavity, and the measured temperature (T ₁ ) And whether or not the measured temperature (T ₁ ) has reached the set temperature (T ₀ ) after the peak of the measured temperature (T ₁ ) is confirmed. And a step of retreating the slide core after confirming that the measured temperature (T ₁ ) has reached the set temperature (T ₀ ). .   The measurement value to be compared with the appropriate value according to any one of claims 1 to 7 is a maximum value of a measurement value of a pulling force that changes for a while from the start to the end of pulling out the slide core. A casting method characterized by the above.

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