JP2627047B2 - Injection molding machine molding condition setting method - 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 for setting molding conditions of an injection molding machine having a speed control area and a pressure control area during an injection process.

[0002]

2. Description of the Related Art Generally, in an injection step in a molding cycle of an injection molding machine, a speed control region for controlling a screw speed (injection speed) to fill a mold cavity with a molten resin in a heating cylinder, and a screw control region. It has a pressure control area for controlling the pressure (holding pressure) to pressurize the resin filled in the cavity. In the speed control area, feedback control of the speed is performed so that the actually measured value of the injection speed matches the preset command value, and when the screw reaches the preset switching point, the pressure is switched to the pressure control area. Then, in the pressure control region, pressure feedback control is performed so that the measured value of the holding pressure matches a preset command value.

It is important to properly set the switching point between the speed control region and the pressure control region in order to ensure a smooth molding operation and obtain a good molded product. For example, in the speed control region, as the filling of the resin progresses,
As the pressure rises, and especially at the end of filling, the pressure rises sharply.If there is an incorrect setting, the mold will be damaged by flashing, or the molded product will not release properly due to overpacking. In many cases, the molding cycle must be interrupted.

For this reason, conventionally, a switching point according to the screw position is set based on the volume of the mold cavity, the capacity of the heating cylinder, and the like, and further, by repeating the test firing, a final trial and error based on the experience and intuition of the operator is performed. Adjustments were being made.

[0005]

However, such a conventional molding condition setting method basically depends on the experience and intuition of the operator and requires repetition of test firing. In addition to an increase in man-hours and wasteful material consumption, considerable skill is required, so that the operators who can set are limited, and it is difficult to obtain high-quality molded products, and there is a problem that the quality tends to vary. By providing a pressure limiter that limits the pressure,
Injection molding machines (see, for example, Japanese Patent Application Laid-Open No. 4-278321) which prevent damage to the mold due to excessive pressure are also known, but they are not suitable for obtaining high quality and uniform molded products. It is enough.

The present invention has been made to solve the problems existing in the prior art, and can easily, quickly and accurately set an optimum switching point from a speed control area to a pressure control area, and achieve high quality and high quality. An object of the present invention is to provide a method for setting molding conditions of an injection molding machine capable of obtaining a uniform molded product.

[0007]

According to the present invention, there is provided a method for setting molding conditions of an injection molding machine, wherein a peak of an injection pressure at a switching point Sh (S1, S2...) From a speed control area Zv to a pressure control area Zp is previously determined. For example, a target value Ps having a certain allowable range is set for the value, the injection pressure in the injection process is detected, and the measured value Pd of the injection pressure at the switching point Sh becomes the target value Ps. In addition, the present invention is characterized in that a molding condition relating to a pressure changing element capable of changing the injection pressure, for example, a switching point Sh based on the screw position or a measurement end point Th (T1, T2...) Based on the screw position is corrected.

In this case, the switching point Sh is used as a pressure changing element.
Is used, when correcting the molding conditions, a predetermined constant correction amount ΔS is added to or subtracted from the switching point Sh set by the screw position in a direction in which the actual measured value Pd of the injection pressure approaches the target value Ps. Can be repeatedly performed for each molding cycle. Further, as another correction method, a correction method of adding or subtracting a predetermined constant correction amount ΔS to or from the switching point Sh set according to the screw position in a direction in which the actual measured value Pd of the injection pressure approaches the target value Ps. Is performed at least once, and from the obtained measured values of the injection pressure at the two switching points S1 and S2, the final correction amount Sr for the measured value Pd of the next molding cycle to become the target value Ps is obtained by calculation. This final correction amount S
The switching point Sh can be corrected by r.

On the other hand, the measurement end point Th is used as a pressure change element.
When correcting the molding conditions, a predetermined constant correction amount ΔT is added or added to the weighing end point Th set by the screw position in a direction in which the measured value Pd of the injection pressure approaches the target value Ps when correcting the molding conditions. The subtraction correction can be repeatedly performed for each molding cycle. Further, as another correction method, correction is performed by adding or subtracting a predetermined constant correction amount ΔT to or from the weighing end point Th set according to the screw position in a direction in which the actual measured value Pd of the injection pressure approaches the target value Ps. Is performed at least once, and from the obtained measured values of the injection pressure at the two switching points T1 and T2, a final correction amount Tr for the measured value Pd of the next molding cycle to become the target value Ps is obtained by calculation. The measurement end point Th can be corrected by the final correction amount Tr.

On the other hand, in the above setting, a quasi-target value Pm smaller than the target value Ps is set in advance, and the amount of the resin R larger than the volume of the mold cavity Ec is measured in the measuring step. Detecting the injection pressure at
The point at which the measured value Pd of the injection pressure reaches the quasi-target value Pm can be used as the switching point Sh. Further, a target amount Cs for the cushion amount is set in advance, the amount of the resin R larger than the volume of the mold cavity Ec is measured in the measuring step, and the cushion amount is detected after the end of the injection step.
The measurement end point Th can be set so that the actually measured amount Cd of the cushion amount becomes the target amount Cs. In addition,
Is the amount of screw tip after the end of the injection process.
This is the gap between the end and the injection nozzle. Therefore, by combining the above methods, both the quasi-target value Pm smaller than the target value Ps and the target amount Cs for the cushion amount are set in advance, and the mold cavity Ec is set in the measuring step.
The amount of the resin R larger than the volume of the resin is measured, and the injection pressure in the injection process is detected, and the measured injection pressure Pd
Is used as the switching point Sh, and at the same time, the cushion amount is detected after the end of the injection process, and the measurement end point Th is set so that the actual measured amount Cd of the cushion amount becomes the target amount Cs. Can be set.

[0011]

According to the method for setting molding conditions of an injection molding machine according to the present invention, the speed control area Zv and the pressure control area Zp are determined in advance.
A target value Ps having a certain allowable range with respect to the peak value of the injection pressure at the switching point Sh is set. In this case, the target value Ps is set to an optimum value based on the type of resin, the projected area of the molded product, the mold clamping force, the experience of the operator, and the like.

On the other hand, in the actual injection step, the measured value Pd of the injection pressure at the switching point Sh from the speed control area Zv to the pressure control area Zp is obtained. And the actual measured value P
d and the target value Ps are compared, and when the actual measurement value Pd is out of the allowable range of the target value Ps, a pressure change element capable of changing the injection pressure, for example, the switching point Sh (forming condition) based on the screw position. Is corrected, whereby the switching point Sh
Is changed and set so that the actual measured value Pd of the injection pressure at the time falls within the allowable range of the target value Ps. Specifically, the switching point Sh
Is added or subtracted for each molding cycle, and this correction is repeated until the actually measured value Pd falls within the allowable range of the target value Ps. Thereby, the optimum switching point Sh at which the actually measured injection pressure value Pd becomes the target value Ps is automatically set. In this case,
If the correction for adding or subtracting the preset fixed correction amount ΔS to or from the switching point Sh is performed at least once, an actual measured value of the injection pressure at the two switching points S1 and S2 is obtained, and the change in the injection pressure is obtained. Since it is estimated (for example, it can be approximated to a change in linearity), the final correction amount Sr for making the measured value Pd of the injection pressure in the next molding cycle fall within the allowable range of the target value Ps can be calculated. The final correction can be performed using the final correction amount Sr.

On the other hand, the same applies when the metering end point Th set by the screw position is corrected as a pressure variable element. In this case, the actual measured value Pd of the injection pressure is also equal to the target value Ps.
Is automatically set to be within the allowable range.

Incidentally, a quasi-target value Pm smaller than the target value Ps is set in advance, the amount of the resin R larger than the volume of the mold cavity Ec is measured in the measuring step, and the injection pressure in the injection step is detected. If the measured injection pressure Pd
Can be used as the switching point Sh, whereby the temporary switching point Sh can be initialized when the switching point Sh is unknown. Further, a target amount Cs for the cushion amount is set in advance, the amount of the resin R larger than the volume of the mold cavity Ec is measured in the measuring step, and the cushion amount is detected after the end of the injection step.
The weighing end point Th can be set so that the actually measured amount Cd of the cushion amount is equal to the target amount Cs. Thereby, the provisional weighing end point Th and the switching point Sh can be set while setting the optimal cushion amount. Can be initialized.

[0015]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings. First Embodiment First, a molding condition setting method according to a first embodiment of the present invention will be described with reference to FIGS.

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

In FIG. 3, M denotes an injection molding machine, particularly, an injection device main body Mi and a controller Mc. The injection device body Mi includes a heating cylinder 3 in the machine base 2, an injection nozzle 4 at the tip of the heating cylinder 3, a hopper 5 at the rear, and a screw 6 inserted therein. On the other hand, the drive of the screw 6 is controlled by the drive mechanism 7. The drive mechanism 7 includes a movable block 9 supported by a rail 8 so as to be slidable in the front-rear direction. A rear end of the screw 6 is rotatably connected to a front end of the movable block 9.
The movable block 9 has a built-in pressure sensor (load cell) 10 for detecting the back pressure of the screw 6, that is, the injection pressure.
An injection servomotor 11 is provided at the rear end of the machine base 2, and the rotating shaft of the servomotor 11 is connected to the rear end of the movable block 9 via a ball screw mechanism. Thus, if the injection servomotor 11 is rotated in the forward or reverse direction, the screw 6 can be moved forward or backward. Reference numeral 12 denotes a rotary encoder attached to the injection servomotor 11, which is used for detecting the position of the screw 6. On the other hand, the servo motor 1 for measuring is mounted on the movable block 9.
The drive gear 14 provided on the rotary shaft of the servo motor 13 meshes with a driven gear 15 provided at an intermediate position of the screw 6. As a result, the servo motor 1 for measuring
By rotating the screw 3 in the forward or reverse direction, the screw 6 can be rotated in the forward or reverse direction. Reference numeral 16 denotes a rotary encoder attached to the servomotor 13 for measurement.

On the other hand, the controller Mc has a computer function unit 21. The computer function unit 21 is a CPU
22, operation unit (setting unit) 23, display unit 24, storage unit 25
And an input / output unit 26. Also, the controller Mc
Has an injection servomotor control unit 27,
Injection servomotor 11 and rotary encoder 12
Connect. Furthermore, the servo motor control unit for measurement 2
The control unit 28 is connected to the servomotor 13 for measurement and the rotary encoder 16. Then, the injection servomotor control unit 27 and the measurement servomotor control unit 28
The pressure sensor 10 is connected to the input / output unit 26. Note that the output of the rotary encoder 12 is directly applied to the computer function unit 21 to obtain the screw position.

Next, a molding condition setting method according to the present invention will be described with reference to FIGS. 1 and 3 and according to a flowchart shown in FIG.

First, the speed control area Zv shown in FIG.
For example, a target value Ps having a certain allowable range with respect to the peak value of the injection pressure at the switching point Sh (S1, S2,...) Is set by the lower limit Ld and the upper limit Lu. In this case, the target value Ps (lower limit value Ld, upper limit value Lu) is set to an optimal value based on the type of resin, the projected area of the molded product, the mold clamping force, the experience of the operator, and the like. Then, the set target values Ps (lower limit Ld, upper limit Lu) are stored in the storage unit 25. Necessary molding conditions such as a measurement value (a measurement end point), an injection speed (Vs in FIG. 1), a holding pressure (Pf in FIG. 1), a switching point Sh by initial setting from the speed control area to the pressure control area, and the like are as follows. The setting is performed in the same manner as in the related art.

On the other hand, the actual molding process is started under the set molding conditions (step 31). The molding step includes a measuring step and an injection step. In the injection step, injection and filling are performed by advancing the screw 6 (step 32). At this time, the forward speed of the screw 6, that is, the injection speed V is controlled to the speed set value Vs as shown in FIG. Further, the injection pressure P increases with the progress of injection filling, and in particular, sharply increases at the end of filling. When the switching point Sh set by the screw position is reached, the control is switched to the pressure control.
In this case, the actual measured value Pd of the injection pressure at the switching point Sh is detected by the pressure sensor 10 (steps 33 and 3).
4). In FIG. 1, the switching point at this time is indicated by S1, the injection pressure is indicated by P1, and the injection speed is indicated by V1. In this case, when the measured value Pd of the injection pressure P at the switching point S1 is compared with the target value Ps, Pd <Ps. Therefore, the switching point Sh is set to a position ahead of the current position, and the measured value Pd is set.
Need to be increased. Therefore, the switching point Sh is changed and set to a switching point (Sh-ΔS) obtained by subtracting a preset fixed correction amount ΔS from the switching point Sh at the current position (steps 35 and 36). Then, when the first molding cycle is completed, the next molding cycle is similarly executed (step 3).
7). By repeating such a correction for each molding cycle,
The switching point Sh is changed forward from S1 in the order of S2 and S3. In the case of FIG. 1, at the third molding cycle, that is, at the switching point S3, the actually measured value Pd falls within the allowable range of the target value Ps. The setting of the switching point Sh is completed. If the actual measurement value Pd and the target value Ps satisfy Pd> Ps, the switching point Sh is sequentially changed and set backward. That is, in this case, a switching point (Sh + ΔS) obtained by adding a preset fixed correction amount ΔS to the switching point Sh is set (step 3).
8, 39).

Thus, at the switching point Sh (S3), if the speed control is switched to the pressure control, the target value Ps
The optimum peak value of the injection pressure falling within the allowable range is obtained. Note that the injection speed V sharply decreases immediately before reaching the switching point Sh, becomes zero when reaching the switching point Sh, shifts to pressure control, and the injection pressure P is controlled to a preset holding pressure Pf. You. In FIG. 1, V2 and P2 denote injection speed and injection pressure in the second molding cycle, respectively.
3 and P3 indicate the injection speed and injection pressure in the third molding cycle, respectively, and Qr indicates the deceleration angle.

On the other hand, as a modified embodiment of the correction method, the correction method shown in FIG. 4 may be used. First, the process of detecting the injection pressure Pd at the switching point Sh is performed according to steps 31 to 34 of the flowchart shown in FIG. 2 (step 30). Then, when the actual measured value Pd of the injection pressure at the switching point Sh is detected, the measured value Pd is compared with the target value Ps, and if Pd <Ps, the switching point Sh is changed and set forward. That is, it is set to a switching point (Sh-ΔS) obtained by subtracting a preset fixed correction amount ΔS from the switching point Sh (steps 41 and 42). Then, when the first molding cycle is completed, the next molding cycle is similarly executed (step 43). In a modified embodiment, such a correction is made at least once and the two switching points S shown in FIG.
1. The actual measured value of the injection pressure in S2 is obtained, and the final correction amount Sr for causing the measured value Pd to fall within the allowable range of the target value Ps is calculated (steps 44 and 45). Therefore, by setting the switching point (Sh-Sr) by using the final correction amount Sr, the optimum switching point Sh can be set by three molding cycles in any state (step 46). . If Pd> Ps, the switching point Sh is set backward. In this case, a point for setting a switching point (Sh + ΔS) obtained by adding a preset fixed correction amount ΔS to the switching point Sh, and a final correction amount S
r can be set in the same manner as described above except that the switching point (Sh + Sr) is set by adding r (steps 47, 48, 49, 5).
0, 51). [Second Embodiment] Next, a molding condition setting method according to a second embodiment of the present invention will be described with reference to FIGS.
This will be described according to the flowchart shown in FIG.

The second embodiment differs from the first embodiment in that the measurement end point Th is used as a pressure changing element. First, the process (step 30) for detecting the actually measured injection pressure value Pd at the switching point Sh is performed according to steps 31 to 34 of the flowchart shown in FIG. At this time, in the second embodiment, the weighing end point Th is detected and stored at the end of weighing after the start of the molding cycle.

On the other hand, as shown in FIG. 5, it is assumed that a weighing end point T1 is set as an initial setting. In this case, when the actual measured value Pd of the injection pressure at the switching point Sh is compared with the target value Ps, Pd <Ps. Therefore, the measurement end point T1 is changed to a position behind the current position, and the measured value Pd is changed. It needs to be raised. Therefore, the weighing end point Th is
A change point (Th + ΔT) obtained by adding a predetermined correction amount ΔT to the weighing end point Th at the current position is changed and set (steps 61 and 62). Then, when the first molding cycle is completed, the next molding cycle is similarly executed (step 63). If such a correction is repeated for each molding cycle, the weighing end point Th is changed from T1 to T2, T3.
In the case of FIG. 5, in the third molding cycle, that is, at the weighing end point T3, the actually measured value Pd falls within the allowable range of the target value Ps, and the weighing end point Th is set.
Is completed. Note that the actual measurement value Pd and the target value Ps are
If Pd> Ps, the weighing end point Th is sequentially changed and set forward. That is, in this case, the switching point (Th−
ΔT) is set (steps 64 and 65).

Thus, the weighing end point Th (S3)
When the control is switched from the speed control to the pressure control at the switching point Sh, the actually measured value Pd of the injection pressure falls within the allowable range of the target value Ps, and the optimum peak value of the injection pressure is obtained. Note that the injection speed V sharply decreases immediately before reaching the switching point Sh, becomes zero when reaching the switching point Sh, shifts to pressure control, and the injection pressure P is controlled to a preset holding pressure Pf. You. In FIG. 5, V1 and P1 are injection speeds and injection pressures in the first molding cycle, respectively, V2 and P2 are injection speeds and injection pressures in the second molding cycle, respectively, and V3 and P3 are respectively in the third molding cycle. Injection speed and injection pressure, Qf indicates an acceleration angle, and Qr indicates a deceleration angle.

On the other hand, as a modified embodiment of the correction method, the correction method shown in FIG. 7 may be used. First, the process of detecting the injection pressure Pd at the switching point Sh is performed according to steps 31 to 34 of the flowchart shown in FIG. 2 (step 30). When the actual measured value Pd of the injection pressure at the switching point Sh is detected, the measured value Pd is compared with the target value Ps.
h is set backward. That is, a switching point (T) obtained by adding a preset fixed correction amount ΔT to the weighing end point Th.
h + ΔT) (steps 71 and 72). Then, when the first molding cycle is completed, the next molding cycle is similarly executed (step 73). In the modified embodiment, such correction is performed at least once to obtain the actual measured values of the injection pressure at the two measurement end points T1 and T2 shown in FIG. 5, and the measured value Pd falls within the allowable range of the target value Ps. Can be obtained by calculation (steps 74 and 75). Therefore, by using this final correction amount Tr, the weighing end point (Th + T
By setting r), the optimum weighing end point Th can be set by three molding cycles in any state (step 76). If Pd> Ps, the weighing end point Th is changed forward. In this case, a switching point (Th-ΔT) is set by subtracting a preset fixed correction amount ΔT from the weighing end point Th, and a switching point (Th-Tr) is set by subtracting the final correction amount Tr. Can be set in the same manner as described above (steps 77, 78, 79, 80, 8).
1).

When the first embodiment or the second embodiment is performed, for example, when the switching point Sh is unknown, for example, after the mold is replaced with a new one, the setting method shown in FIG. The temporary switching point Sh can be initially set, thereby preventing die damage and the like caused by the incorrect setting of the switching point Sh. That is, a quasi-target value Pm smaller than the target value Ps is set in advance (step 91). Then, the molding cycle is started, and the amount of the resin R larger than the volume of the mold cavity Ec is measured in the measuring step (step 92, FIG. 9).
reference). On the other hand, in the injection step, the injection pressure is detected, and when the measured value Pd of the injection pressure reaches the quasi-target value Pm, the pressure is switched to the pressure control (pressure holding step), and the switching point Sh is detected and stored (step 93). , 94, 95, 96). Since the switching point Sh obtained from this is a provisional set value, after that,
In the same manner as in the first embodiment, a change setting by correction for the switching point Sh is performed (step 97).

If the switching point Sh is unknown,
The optimal cushion amount, the measurement end point Th, and the switching point Sh can also be initialized. In this case, FIGS. 9 and 10
As shown in (2), a quasi-target value Pm smaller than the target value Ps and a target amount Cs for the cushion amount are set in advance (step 100). And start the molding cycle,
Resin R larger than the volume of mold cavity Ec in the measuring process
Is measured (step 101, see FIG. 9). on the other hand,
In the injection process, the injection pressure is detected, and the measured injection pressure Pd
Has reached the quasi-target value Pm, the control is switched to the pressure control (pressure keeping step), and the switching point Sh is detected and stored (steps 102, 103, 104, 105). Further, after the injection step is completed, the actual measured amount Cd of the cushion amount is detected (step 105), and the actual measured amount Cd becomes the target amount Cs.
The weighing end point Th is set. That is, the measured amount Cd is compared with the target amount Cs, and if Cd ≧ (Cs + 1 molding amount), the remaining amount of the resin R is excessive, so that the next molding cycle (injection step) is performed without performing measurement. Are repeated (steps 106 and 107). On the other hand, Cd <
If (Cs + 1 molding amount), a necessary weighing value, that is, a weighing end point Th is calculated by calculation, and the weighing end point Th is initialized as a provisional value (step 108).
FIG. 9 shows a state in which the first cushion amount is the actually measured amount C1, and in the third molding cycle, the actually measured amount C3 that matches the target amount Cs is obtained. The switching point Sh is also updated in accordance with the change of the weighing end point Th (Step 109). The update of the switching point Sh may be changed each time based on the actually measured value, or may be changed by calculation from the change result of the weighing end point Th. And after this,
As in the second embodiment, a change setting by correction for the weighing end point Th is performed (step 110). In FIG. 9, E denotes a mold including a fixed mold Ea and a movable mold Eb, and C2 denotes an actual measurement in a second molding cycle. Also, in FIG.
The same parts as those in FIG. 3 or FIG. 5 are denoted by the same reference numerals.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the switching point and the measurement end point are illustrated as the pressure changing elements, but any other pressure changing element that can change the injection pressure can be used. Further, the target value may be set at a constant value. Furthermore, a type using a servomotor as a screw driving mechanism has been described as an example, but a type using a hydraulic circuit can be similarly implemented. In addition, it is possible to arbitrarily change the configuration, technique, and the like of the details without departing from the gist of the present invention.

[0031]

As described above, the present invention relates to a method for setting a molding condition of an injection molding machine having a speed control region and a pressure control region for a screw during an injection process. A target value is set with respect to the peak value of the injection pressure at the time, the injection pressure in the injection process is detected, and the injection pressure can be changed so that the measured value of the injection pressure at the switching point becomes the target value. Since the molding conditions relating to the changed element are corrected, the following remarkable effects are obtained.

[0032] Since the optimum switching point from the speed control area to the pressure control area can be automatically set, easy, quick and accurate setting is guaranteed. Can be significantly reduced.

At the point of switching from the speed control region to the pressure control region, an injection pressure having an optimum magnitude that becomes a peak is applied, so that a high-quality and uniform molded product can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a change characteristic of an injection speed and an injection pressure with respect to a screw position for explaining a molding condition setting method according to a first embodiment of the present invention;

FIG. 2 is a flowchart for explaining a molding condition setting method according to the embodiment;

FIG. 3 is a block diagram of an injection molding machine capable of implementing a molding condition setting method according to the present invention;

FIG. 4 is a flowchart for explaining a molding condition setting method according to a modification of the embodiment;

FIG. 5 is a graph showing a change characteristic of an injection speed and an injection pressure with respect to a screw position for explaining a molding condition setting method according to a second embodiment of the present invention;

FIG. 6 is a flowchart for explaining a molding condition setting method according to the embodiment;

FIG. 7 is a flowchart for explaining a molding condition setting method according to a modification of the embodiment;

FIG. 8 is a flowchart for explaining a method of tentatively setting a switching point used in the molding condition setting method according to the present invention;

FIG. 9 is a graph showing a change characteristic of an injection speed and an injection pressure with respect to a screw position for explaining a method for provisionally setting a measurement end point used in the molding condition setting method according to the present invention;

FIG. 10 is a flowchart for explaining a method for provisionally setting a weighing end point used in the molding condition setting method;

[Explanation of symbols]

 Zv Speed control area Zp Pressure control area Sh Switching point S1 Switching point Ps Target value Pd Actual measurement value Th Measurement end point T1 Measurement end point Pm Semi-target value Ec Mold cavity R Resin Cs Target quantity Cd Actual quantity

Claims (11)

(57) [Claims] In a method for setting a molding condition of an injection molding machine having a speed control region and a pressure control region for a screw during an injection step, the injection pressure peak value at a switching point from the speed control region to the pressure control region is determined in advance. In addition to setting the target value, the injection pressure in the injection step is detected, and the molding conditions relating to the pressure changing element capable of changing the injection pressure are set so that the actual measured value of the injection pressure at the switching point becomes the target value. A method for setting a molding condition of an injection molding machine, wherein the molding condition is corrected. 2. The molding condition setting method for an injection molding machine according to claim 1, wherein said target value is set with a certain allowable range. 3. The molding condition setting method for an injection molding machine according to claim 1, wherein the pressure change element is the switching point set by a screw position. 4. A correction for adding or subtracting a predetermined fixed correction amount to or from the switching point set by a screw position in a direction in which an actual measured value of an injection pressure approaches the target value when correcting molding conditions. The method according to claim 1 or 3, wherein the method is repeated for each molding cycle. 5. A correction for adding or subtracting a predetermined correction amount to or from a switching point set by a screw position in a direction in which an actual measured value of an injection pressure approaches the target value when correcting molding conditions. At least once,
From the measured injection pressure at the two switching points obtained,
4. The injection molding machine according to claim 1, wherein a final correction amount for an actual measurement value of a next molding cycle to become the target value is obtained by calculation, and the switching point is corrected by the final correction amount. Molding condition setting method. 6. The molding condition setting method for an injection molding machine according to claim 1, wherein the pressure change element is a measurement end point set by a screw position. 7. A correction for adding or subtracting a predetermined fixed correction amount to or from the weighing end point set by a screw position in a direction in which an actual measured value of an injection pressure approaches the target value when correcting molding conditions. 7. The method for setting molding conditions of an injection molding machine according to claim 1, wherein the step is repeated for each molding cycle. 8. A correction for adding or subtracting a predetermined fixed correction amount to or from the weighing end point set by a screw position in a direction in which an actually measured value of an injection pressure approaches the target value when correcting molding conditions. Is performed at least once, and from the measured injection pressure values obtained at the two switching points obtained, a final correction amount for the measured value of the next molding cycle to become the target value is obtained by calculation, and the final correction amount is used to calculate the final correction amount. 7. The molding condition setting method for an injection molding machine according to claim 1, wherein the weighing end point is corrected. 9. A quasi-target value smaller than the target value is set in advance, a resin amount larger than the volume of a mold cavity is measured in a measuring step, and an injection pressure in an injection step is detected. 2. The molding condition setting method for an injection molding machine according to claim 1, wherein a point at which an actually measured value reaches a quasi-target value is used as said switching point. 10. A target amount for a cushion amount is set in advance, a resin amount larger than the volume of a mold cavity is measured in a measuring step, and a cushion amount is detected after an injection step. 7. The molding condition setting method for an injection molding machine according to claim 1, wherein a measurement end point is set so as to be the target amount. 11. A quasi-target value smaller than the target value and a target amount for the cushion amount are set in advance, a resin amount larger than the volume of the mold cavity is measured in the measuring step, and the injection pressure in the injection step is reduced. Detecting and using the point at which the measured value of the injection pressure has reached the quasi-target value as the switching point, and detecting the cushion amount after the end of the injection step,
7. The molding condition setting method for an injection molding machine according to claim 1, wherein the measuring end point is set such that an actually measured value of the cushion amount becomes the target amount.