JPH0512136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for setting molding conditions for an injection molding machine that can automatically set molding conditions.

Conventional technology When creating a new product using an injection molding machine, a new mold is installed, a test run is performed, parameters for injection molding conditions such as injection speed and injection pressure are set, and the optimum values are determined using a trial and error method. I had made a choice. Therefore, the conventional method required a skilled person to set the parameters, and the parameters were set over a long period of time based on the experience of the skilled person. Also, a method is known in which initial conditions are set in advance by incorporating a program, but even in this case, the parameter values of injection molding conditions vary depending on mold conditions and external conditions.
It was very difficult to set the optimum value.

Problems to be Solved by the Invention The present invention improves the above-mentioned drawbacks of the prior art, and improves the molding conditions at least by controlling the temperature of each heating zone of the mold, nozzle, and heating cylinder by setting the resin material of the molded product. The object of the present invention is to provide a method for setting molding conditions for an injection molding machine that automatically sets the cushion amount, injection speed, and injection pressure.

Means for Solving the Problems The present invention provides an injection molding machine that performs injection by driving a servo motor. The molding conditions obtained through experience as conditions for molding a good product in accordance with the time from the start of injection to the set maximum injection pressure and the injection amount during that time, at least the cushion amount, injection speed, and injection pressure. The value is stored in a storage device in the control device of the injection molding machine, and when the resin material is input to the control device when setting molding conditions, the control device stores the value stored in the storage device. The set temperature of the mold, nozzle, and each heating zone is read and automatically set. When the temperature of the mold, nozzle, and each heating zone reaches the set temperature, the mold is automatically opened and the injection is performed for the set number of times. Thereafter, after the mold is clamped, injection is performed at the predetermined command injection speed, the time and injection amount until the set maximum injection pressure is detected, and at least the injection amount is adjusted according to the detected time and injection amount. The values of the amount, injection speed, and injection pressure were read from the storage device, and the read values were automatically set as molding conditions.

Function When the resin material of the molded product is input, the set temperature of the mold, nozzle, and each heating zone for the resin material stored in the storage device is read out and automatically set, and the temperature of the mold, nozzle, and each heating zone is read out and automatically set. When the temperature of the heating zone reaches the set temperature, injection is performed the set number of times with the mold open. After a so-called purge is performed and the mold is then clamped, injection is performed at a predetermined command speed, and the time from the start of injection at which the maximum injection pressure is detected and the injection amount during that time are detected, and this time and injection amount are measured. cushion amount, injection pressure,
The injection speed is read from the storage device, and the read value is automatically set as the set value. As a result, by simply setting the resin material of the molded product, the mold, nozzle, temperature of each heating zone, cushion amount, injection pressure, and injection speed are automatically set to suit the resin material and mold used. Ru.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 and 2 are molds, 3 is a movable plate, 4 and 5 are fixed plates, and the fixed plate 5 and movable plate 3 are equipped with the metal molds mentioned above. Molds 2 and 1 are fixed. Reference numeral 6 denotes a ball screw fixed to the movable plate 3, which is driven by a servo motor M3 to connect a gear 8 and a nut 7 having a gear that meshes with the gear 8.
The ball screw screwed into the nut 7 is moved in the left-right direction in FIG. 1, and the movable platen 3 is moved to open and close the mold. 11 is a heating cylinder, 12 is a nozzle provided at the tip of the heating cylinder, and each heating zone of the heating cylinder 11,
Temperature sensors S1 to Nozzle 12 and molds 1 and 2
S6 is provided. 15 is a heating cylinder 11
A spline shaft is provided on the screw shaft of the inner screw, and a gear 13 having a spline groove is engaged with the spline shaft 15, and the servo motor M1
The gear 13 is rotated by the drive of the gear 14, thereby rotating the screw.
Further, a ball screw 17 is connected to the spline shaft 15 of the screw shaft via a thrust bearing 16.
A nut 18 having a gear is screwed into the ball screw 17, and the rotation of the servo motor M2 rotates the nut 18 via the gear 19, moving the ball screw 17 to the left in FIG. People are starting to do this. Note that P1 to P3 are position detectors provided in the servo motors M1 to M3.
30 is a control device, 31 is a central processing unit (hereinafter referred to as
32 is a ROM that stores the control program of the control device 30, 33 is a RAM for arithmetic processing, etc., and 34 is resin data such as the temperature of the heating cylinder etc. determined by the resin material, the amount of cushioning, and the injection amount. A bubble memory stores a table of parameter values such as pressure and injection speed, 35 is a manual input device, 36 is an input circuit, and position detectors P1 to P
3. Signals from A-D converters 23 to 28 that convert signals from temperature sensors S1 to S6 into digital signals and drive current detectors of drive circuits 21 and 22 of servo motors M2 and M3 are input. 37
is an output circuit, and a control device (not shown) that controls the temperature of drive circuits 20 to 22 of each servo motor M1 to M3, and each heating zone of the mold, nozzle, and heating cylinder.
It outputs an output signal to.

In the above-described configuration, the operation of this embodiment will be explained along with the operation flow shown in FIG. 2A and B.

First, new molds 1 and 2 are mounted on the movable platen 3 and fixed platen 5, and the resin material of the product to be manufactured using the molds 1 and 2 is selected and inputted from the manual input device 35 (step 101). Then, the CPU 31 selects each heating zone and nozzle 1 of the heating cylinder 11 stored in the bubble memory 34 in correspondence with the selected resin material.
2. Read the temperatures T ₁ to _{T 6} of the molds 1 and 2, and check the read set temperatures T ₁ to _{T 6} and the temperature sensor S at each point.
The temperatures measured at steps 1 to S6 and inputted after A-D conversion are compared with S ₁ to S ₆ (steps 103 to 108), and the temperature at each temperature measurement point S1 to S6 is determined to be the set temperature T ₁ to T. ₆
Wait until it exceeds.

In addition, in FIG. 2, the step of comparing the temperatures measured by the temperature sensors S3 to S5 and the set temperatures _T3 to _T5 is omitted.

In this way, the temperature of each heating zone of the mold, nozzle, and heating cylinder is controlled, and when all of them reach the set temperature, the CPU 31 sets the index N to zero (step 109), and controls the motor through the output circuit 37. M
1 at a constant speed to rotate the screw (step 110). As the screw rotates, the resin of the material becomes plasticized, and as the molten material increases, the screw is pushed back by the reaction force, but the CPU 31 controls the drive current of the servo motor M2 to control the torque of the servo motor M2. (step 111), and move the screw rearward while applying constant back pressure. Then, the position of the screw is detected by the signal from the position detector P2 of the servo motor M2, and the screw is moved backward until the position reaches the maximum weighing point _L0 of this injection molding machine (step 112), and the screw is moved back until the position reaches the maximum weighing point L0 of the injection molding machine. When L ₀ is reached,
The drive of the servo motor M1 is stopped, and the servo motor M2 is driven to move the screw forward and perform injection (step 113). In this case, the injection is not injection into a mold, but is a simple injection (so-called purge). Then, 1 is added to the index N (step 114), so that the value of the index becomes a constant value N ₀ , for example, 3
(Step 115), perform the discard shots from Step 110 above. Next, when a certain number of throw-offs are completed, the servo motor M3 is driven to perform the mold clamping process (step 116), and the servo motor M1 is driven at a constant speed as described above, and the torque control of the servo motor M2 is controlled. and then move the screw back to the maximum weighing point L ₀ and weigh (step
117 to 119), when the maximum weighing point _L0 is reached, the drive of the servo motor M1 is stopped, and the timer T and the counter C that counts the number of output pulses to the servo motor M2 are reset and started (step 120,
121). At the same time, the servo motor M2 is driven at a commanded speed, for example, half of the maximum speed, to move the screw forward and perform injection (step 122).
Then, it is determined whether the drive current _I2 of the servo motor M2 has reached the drive current value _i0 that occurs when the injection pressure reaches the maximum (step 123). That is, when the mold is filled with molten resin, the advance of the screw is stopped, but the servo motor M2 tries to advance the screw further, so that the drive current increases and the injection pressure increases. Therefore, the drive current value _i0 is set as the maximum injection pressure generation drive current. When this value is reached, the value T ₀ of the timer T and the value C ₀ of the counter C at that time are stored (step
124). As a result, the value T ₀ of the timer T indicates the time from injection until the maximum injection pressure is reached, that is, the filling completion time, and the value C ₀ of the counter C indicates the injection amount (filling amount) up to that time. Next, the drive current _I2 of the servo motor M2 is set to the value of the drive current _i1 necessary for the primary pressure holding, and the timer T is reset and started again. Wait until t ₁ is reached (steps 125, 126),
Next, set the drive current _I2 of the servo motor M2 to the secondary holding current _i2 , reset the timer T again,
The pressure is held until the second pressure holding time _t2 is reached (steps 127 and 128), and when the second pressure holding time _t2 has elapsed, the drive of the servo motor M2 is stopped and the servo motor M3 is driven. to open molds 1 and 2,
Take out the product (steps 129, 130). on the other hand,
The CPU 31 calculates the cushion amount A and the injection pressure B stored in the table of the bubble memory 34 corresponding to the time T ₀ until the maximum injection pressure detected by the timer T and counter C, and the injection amount C ₀ during that time. ,
The injection speed D is read and set in the RAM 33 (step 131). In other words, time T ₀ is the time when molds 1 and 2
It shows the time required to fill the molding material into the cavity, and the injection amount C ₀ means the filling amount (cavity volume). The cushion amount A, which is the amount of molten resin left in the heating cylinder when the injection is completed and the mold is filled with resin, needs to be large if the injection amount (filling amount) _C0 is large. Since it is known from experience, the cushion amount A is stored in the above table as a value approximately proportional to the injection amount C ₀ .

Furthermore, by dividing the injection amount C ₀ by the time T ₀ , the injection amount per unit time (C ₀ /T ₀ ) can be obtained, and this injection amount per unit time is inversely proportional to the flow resistance of the molding material. . This flow resistance is one of the important factors representing the cavity shape. Moreover, this flow resistance, injection speed, and injection pressure have the following relationship.

Injection pressure ∝ (flow resistance) × injection speed As a result, it means that the flow resistance can be determined from the injection amount C ₀ and time T ₀ , and the degree of proportionality between injection speed and injection pressure increases depending on the size of flow resistance. As can be seen from the formula, the allowable injection speed that keeps the injection pressure within the allowable range is found. Once either the optimum injection speed or the injection pressure is determined, the other will be determined based on the relationship among the injection pressure, flow resistance, and injection speed described above. Therefore, since the injection pressure B and injection speed D are empirically known to be approximately suitable for the injection amount C ₀ and time T ₀ , the servo motor is operated at a predetermined speed (for example, 1/2 the maximum speed). The suitable injection pressure B and injection speed D corresponding to the injection amount C ₀ and time T ₀ obtained when the maximum injection pressure is detected when driving and injecting are stored in the table above based on experiment and experience. Then, the injection pressure B and injection speed D corresponding to the detected injection amount C ₀ and time T ₀ are read and set. Then, the servo motor M2 is driven again to dump the remaining material in the heating cylinder, and then the servo motor M3 is driven to perform the mold clamping process (steps 132 and 133). Then, the servo motor M1 is driven again to rotate the screw, the screw is retreated while applying back pressure by controlling the torque of the servo motor M2, and a metering process is performed.
When the value obtained by adding _C0 and the value of the set cushion amount A obtained from the table of the bubble memory 34 is reached, the servo motor M1 is stopped and the metering is stopped (steps 134 to 136). Next, the servo motor M2 is driven to advance the screw at the set injection speed D to perform injection, and the drive current I ₂ of the servo motor M2 is
When the current value reaches the current value corresponding to the set injection pressure B, the value of the drive current _I2 is changed to the current value _i1 corresponding to the first holding pressure, and the timer T is reset and started (steps 137 to 139). Then, timer T is the first
When the next pressure holding time _t1 is reached, the drive current _I2 of the servo motor M2 is converted to the second pressure holding current _i2 , and the timer T is reset and started again (step
140, 141). When the timer T elapses the second holding pressure time _t2 , the servo motor M2 is stopped, the servo motor M3 is driven, the mold is opened, and the product is taken out (steps 142 to 144). Then, the product is inspected (step 145), and if it is suitable, production of the product is started under the molding conditions set above (step 145).
146). However, if the product has insufficient or excessive material, sink marks, or warpage, the molding conditions are reset by operating the manual input device to increase or decrease molding conditions such as the amount of cushioning and injection pressure (step 147). , the process from step 132 onwards is performed again to select and set parameters for molding conditions for an optimal product.

Effects of the Invention According to the present invention, when using a new mold, by simply setting the resin material to be used, the temperature of each heating zone of the mold, nozzle, and heating cylinder can be set to a temperature suitable for the resin material to be used. After that, after purging, test firing is performed once, and from the time until the maximum injection pressure obtained by the test firing and the injection amount injected during that time, at least the cushion amount of the molding conditions is determined from the table stored in the storage device. , injection speed,
Since the injection pressure value is automatically determined and set, the mold, nozzle,
Since the temperature of each heating zone is set to a value suitable for the resin material, and the cushion amount, injection speed, and injection pressure are automatically set to almost appropriate values, test injections are performed 2 to 3 times. Just by manually modifying the molding conditions, you can easily set the optimal cushioning amount, injection speed, and injection pressure.
Various temperature settings, cushion amount, injection speed,
There is no need to spend much time setting the injection pressure and other molding conditions. In addition, since the device automatically sets molding conditions such as various temperatures, cushioning amounts, injection speeds, and injection pressures, even unskilled workers can easily set molding conditions, instead of relying on the experience and intuition of experts. There is less need to rely on it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 (a) and (b) are operational flows of the same embodiment. 1, 2... Mold, M1-M3... Servo motor, 11... Heating cylinder, S1-S6... Temperature sensor.

Claims (1)

[Claims] 1. In a method of setting molding conditions in an injection molding machine that drives a servo motor to perform injection, the set temperature of each heating zone of a mold, nozzle, and heating cylinder and a predetermined command injection speed are set for each resin material. When performing injection at The value of is stored in the storage device in the control device of the injection molding machine, and when the resin material is input to the control device when setting molding conditions, the control device stores the value stored in the storage device. The set temperature of the mold, nozzle, and each heating zone is read and automatically set. When the temperature of the mold, nozzle, and each heating zone reaches the set temperature, the mold is automatically opened and the injection is performed for the set number of times. Then, after the mold is clamped, injection is performed at the predetermined command injection speed, the time and injection amount are detected until the set maximum injection pressure is detected, and at least A method for setting molding conditions in an injection molding machine, comprising reading values of a cushion amount, injection speed, and injection pressure from the storage device, and automatically setting the read values as molding conditions. 2. The method for setting molding conditions in an injection molding machine according to claim 1, wherein the injection pressure is detected by detecting the drive current of a servo motor that moves the screw forward and performs injection.