JP4568343B2 - Acceleration / deceleration control method for machine moving parts - Google Patents

Description

  The present invention relates to an acceleration / deceleration control method for a movable part of a machine whose position and speed are controlled by a servo motor.

In various machines such as industrial machines, the position and speed of the movable part are controlled by driving the movable part of the machine with a servo motor and controlling the speed and position of the servo motor.
For controlling the position and speed of the movable part, a control device such as a numerical control device performs acceleration / deceleration control based on the moving distance from the start point to the end point and the set speed at which the movable part starts moving. A movement command is generated, the servo motor is driven by the movement command, and the movable part is driven and controlled. In general, this acceleration / deceleration control is performed to accelerate the speed to a command speed and to decelerate and stop based on a set time constant.

  Rather than controlling the speed at a constant acceleration determined by the set time constant, the method of controlling the motor speed by changing the acceleration is an output determined by machine friction, gravity value, motor output torque performance, etc. Obtain a limited acceleration curve that represents possible acceleration as a function of speed, set a speed-acceleration curve to match or approximate the limited acceleration curve, and based on the speed-acceleration curve, A method for controlling the speed of the motor is known (see Patent Document 1).

  Furthermore, in the drive control of each joint axis of the robot, the acceleration / deceleration with respect to the coordinate value of the joint axis is stored in a table, and at the start of movement, the start point coordinate value of the joint axis and the end point coordinate of the joint axis from the target position Find the acceleration corresponding to the value from the table, set it as the acceleration at the start point and the deceleration at the end point, and select the minimum acceleration and deceleration from the set acceleration and deceleration of each joint axis, An invention in which the speed is controlled is also known (see Patent Document 2).

  Moreover, in an electric injection molding machine that drives a movable part such as a screw that injects molten resin into a mold with a motor, the injection process is divided into a plurality of stages according to the screw position, and the injection speed ( In this case, in order to control the speed of the resin flowing in the mold, the viscosity of the resin, the shape of the mold, and the resin filling state in the mold are controlled. Therefore, it is necessary to avoid sudden changes in the injection speed, so the acceleration when switching to the speed of each stage and the speed to the next stage is set for each stage, and the acceleration at each stage acceleration and deceleration is set. For example, when the resin flows through the gate of the molded product, the molding speed is rapidly reduced, and when the resin enters the product part from the gate, the molding process is performed so that the flow of the resin is not disturbed. It has been known.

  In general, a mechanism for amplifying torque and speed is provided between the motor and the machine movable part, and the machine movable part is driven via these mechanisms. For example, in an industrial machine such as an electric injection molding machine or an electric press machine, the rotational force of the motor is often increased by using an amplification mechanism such as a toggle mechanism or a crank mechanism.

JP 2002-132349 A JP-A-4-352013

  When a speed amplifying mechanism such as a toggle mechanism or a crank mechanism is used, the speed of the movable part becomes faster than the speed of the motor that drives the movable part, and the effect of shortening the machine operation cycle time can be achieved. However, there is a problem that the speed fluctuation of the movable part increases depending on the position of the speed amplification mechanism, and even if the rotational speed of the motor is constant, the speed of the movable part increases or decreases rapidly depending on the position of the speed amplification mechanism. Or the speed fluctuates greatly and a large acceleration occurs. Therefore, in order to perform optimum speed control on the movable part, it is necessary to change the acceleration and speed according to the position of the motor (position of the speed amplification mechanism).

  The invention described in Patent Document 1 described above sets acceleration as a function of speed. In addition, in the example of speed control of the injection process in the injection molding machine and the invention described in Patent Document 2, the acceleration is changed depending on the position, but the speed is controlled by changing the acceleration for each movement command. is there. Since the movement position is divided into a plurality of movement commands and the acceleration at the start and end of movement by each movement command is controlled, it is necessary to divide the movement position into a plurality of movement commands.

  Accordingly, an object of the present invention is to provide an acceleration / deceleration control method capable of changing acceleration according to the position of a motor during movement with a single movement command.

The present invention includes a speed amplification mechanism in which a speed amplification factor changes according to a position, and drives and controls a movable part of a machine via a speed amplification mechanism by a servo motor based on a movement command from a control device. An acceleration / deceleration control method for controlling the position and speed of
The acceleration corresponding to the position of the servo motor that is moving to the target position according to the movement command is obtained from the reciprocal of the speed amplification factor of the speed amplification mechanism and set in the control device in advance as an acceleration pattern. , based on the acceleration pattern, Ru deceleration control method der mechanical movable part to control the speed to change the acceleration in accordance with the position of the servomotor.
The setting of the acceleration pattern includes an aspect in which acceleration corresponding to the position of the servo motor is set and stored in a table, and an aspect in which a function indicating the relationship between the acceleration corresponding to the position is set.

The acceleration pattern is obtained by measuring the speed according to the position of the movable part driven by the servo motor via a speed amplification mechanism.

  According to the present invention, the acceleration pattern can be accelerated and decelerated at an acceleration different from the acceleration during deceleration, even during acceleration and deceleration, depending on the position of the servo motor. Deceleration control is possible. In addition, when a speed amplification mechanism such as a toggle mechanism or a crank mechanism is used, the speed and acceleration of the servo motor of the drive source are different from the speed and acceleration of the movable part driven through the speed amplification mechanism. However, by setting the acceleration pattern, it becomes easy to control the speed and acceleration of the movable part to desired ones.

  Hereinafter, an example in which the acceleration / deceleration control method for a machine movable part of the present invention is applied to drive control of a movable platen (movable part) of an electric injection molding machine will be described.

FIG. 1 is a schematic diagram of an electric injection molding machine as an embodiment to which the acceleration / deceleration control method of the present invention is applied.
A nozzle portion 2 is attached to the tip of the injection cylinder 1, and an injection screw 3 is inserted into the injection cylinder 1. The injection screw 3 is provided with a pressure sensor 5 such as a load cell that detects a resin pressure by the pressure applied to the injection screw 3, and the injection screw 3 is configured by a screw rotation servo motor M2 and includes a pulley, a belt, and the like. It is rotated via the transmission means 6. The injection screw 3 is driven by a servo motor M1 for injection via a transmission means 7 including a mechanism for converting a rotational motion such as a pulley, belt, ball screw / nut mechanism, etc. into a linear motion. It is moved in the axial direction. Reference numeral P1 is a position / speed detector that detects the position and speed in the axial direction of the injection screw 3 by detecting the position and speed of the servo motor M1, and reference numeral P2 is the position of the servo motor M2. This is a position / speed detector that detects the rotational position and speed of the injection screw 3 by detecting the speed. Reference numeral 4 denotes a hopper that supplies resin to the injection cylinder 1.

  The mold 11 is attached to the fixed platen 8 and the movable platen 9, and a toggle mechanism 13 that is an amplification mechanism for amplifying torque and speed is provided between the movable platen 9 and the rear platen 10. The movable platen 9 is provided with a projecting servo motor M3 for projecting a molded product in the mold, and a projecting pin is projected into the mold through a transmission means 16 composed of a pulley, a belt and the like. Remove the molded product from the mold. The rear platen 10 is provided with a mold opening / closing servo motor M4, and drives a ball screw 14 rotatably supported on the rear platen 10 through a transmission means 15 constituted by a pulley, a belt and the like. The ball screw 14 is screwed into a nut provided on the cross head 13a of the toggle mechanism 13, and the ball screw 14 is rotated by the rotation of the mold opening / closing servo motor M4, so that the cross head 13a integrated with the nut is left and right in FIG. The movable platen 9 is moved by expanding and contracting the link of the toggle mechanism 13 to open and close the mold and clamp the mold. P3 and P4 are position / speed detectors for detecting the rotational positions and speeds of the servo motors M3 and M4.

  The control device 30 of the injection molding machine has a CNC CPU 40 that is a microprocessor for numerical control, a PMC CPU 39 that is a microprocessor for a programmable machine controller, and a servo CPU 37 that is a microprocessor for servo control. By selecting mutual input / output, information can be transmitted between the microprocessors.

  The servo CPU 37 is connected to a ROM 35 that stores a control program dedicated to servo control that performs processing of a position loop, a speed loop, and a current loop, and a RAM 36 that is used for temporary storage of data. The servo CPU 37 can detect pressure signals from a pressure sensor 5 that detects various pressures such as injection pressure provided on the injection molding machine main body side via an A / D (analog / digital) converter 38. It is connected. Further, the servo CPU 37 has servo amplifiers 34, 33 for driving the servo motors M1, M2, M3, M4 for injection, screw rotation, product protrusion, and mold opening / closing on the basis of a command from the CPU 37. 32 and 31 are connected, and outputs from position / speed detectors P1, P2, P3, and P4 attached to the servo motors M1, M2, M3, and M4 are fed back to the servo CPU 37.

  A ROM 43 storing a sequence program for controlling the sequence operation of the injection molding machine and a RAM 44 used for temporary storage of calculation data are connected to the PMC CPU 39, and an automatic operation program for overall control of the injection molding machine is connected to the CNC CPU 40. Are connected to a ROM 45 that stores data and the like, and a RAM 46 that is used for temporary storage of calculation data.

  A molding data storage RAM 41 composed of a non-volatile memory is a molding data storage memory for storing molding conditions relating to injection molding work, various set values, parameters, macro variables, and the like.

  A CRT / MDI (manual data input device) 47 is connected to a bus 48 via a CRT display circuit 42, and can be used to select a graph display screen, a function menu, and input various data. A numeric keypad and various function keys are provided. Note that a liquid crystal display device may be used as the display device.

  With the above configuration, the PMC CPU 39 controls the sequence operation of the entire injection molding machine, and the CNC CPU 40 instructs the servo motor of each axis to move based on the operating program of the ROM 45 and the molding conditions stored in the molding data storage RAM 41. The servo CPU 37 is based on the movement command distributed to each axis and the position and speed feedback signals detected by the position / velocity detectors P1, P2, P3, and P4 as in the conventional case. Servo control such as position loop control, speed loop control, and current loop control is performed, so-called digital servo processing is performed, and drive control of each servo motor M1, M2, M3, and M4 is performed.

  The above-described configuration is the same as that of a conventional control device for an electric injection molding machine. In this embodiment, acceleration / deceleration control according to the present invention is performed in a mold closing process and a mold opening process in which a movable platen 9 is driven to open and close a mold. Apply the method. Moreover, it may be applied to the injection process.

  The movable platen 9 which is a movable part is driven by the mold opening / closing servomotor M4 via the toggle mechanism 13, so the speed and acceleration of the mold opening / closing servomotor M4 and the moving speed and acceleration of the movable platen 9 are as follows. It is not proportional but different. On the other hand, since the movable side of the mold 11 is fixed to the movable platen 9 and the purpose is to control the opening / closing and mold clamping operations of the mold 11, the position, speed, Need to control acceleration.

  Since the movable platen 9 is driven by the mold opening / closing servo motor M4, the position, speed, and acceleration of the movable platen 9 are controlled by controlling the position, speed, and acceleration of the mold opening / closing servo motor M4. Will be controlled by. However, the position, speed, and acceleration of the mold opening / closing servo motor M4 and the movable platen 9 are not proportional to each other. Therefore, even if the mold opening / closing servo motor M4 is rotated at a constant rotational speed, the speed and acceleration of the movable platen 9 are increased. Changes depending on the position of the mold opening / closing servomotor M4. Since the mold opening / closing servo motor M4 and the cross head 13a operate in a predetermined proportional relationship, if the position, speed, and acceleration of the cross head 13a are determined, the position, speed, and acceleration of the mold opening / closing servo motor M4 are also determined. become.

FIG. 2 is a diagram showing a state in which the link of the toggle mechanism 13 is fully extended. As shown in FIG. 2, the link pivot points of the toggle mechanism 13 are Q1, Q2, Q3, Q4, and the pivot points. The length of the link between them is L1, L2, L3, and L4.
3 to 5 are explanatory diagrams for analyzing the position and speed of the cross head 13a and the position and speed of the movable platen 9. FIG. FIG. 3 shows the state of the toggle mechanism 13 with the link fully extended. When the configuration of the toggle mechanism 13 is determined, each length L11, L12, shown in FIG. The angles a, b, and c are also constants that are determined. The distance XCH0 from the rear platen 10 to the cross head 13a and the distance XP0 from the rear platen 10 to the movable platen 9 are also constants. The relationship between these constants is as follows.
L2 = √ (L11 ² + L12 ² )
a = tan ^-1 (L12 / L11)
b = sin ⁻¹ (B / (L1 + L3))
c = sin ^-1 ((A + L2 * sin (ab)) / L4)
XCH0 = L2 * cos (ab) -L4 * cos (c)
XP0 = (L1 + L3) * cos (b)
Thus, the distance XCH0 from the rear platen 10 to the cross head 13a and the distance XP0 from the rear platen 10 to the movable platen 9 are also constants determined by the configuration of the toggle mechanism.

FIG. 4 shows a state when the crosshead 13a is moved by XCH from the state of FIGS. 2 and 3 in which the link of the toggle mechanism 13 is fully extended. Further, the angles of the links are set to ψ1 to ψ3 as shown in FIG.
If the distance from the position of the rear platen 10 to the crosshead 13a at this time is Y,
Y = XCH0-XCH
It becomes.
FIG. 5 shows the link (L2) between the pivot point Q1 and the pivot point Q2 and the line of the moving platen 9 in the direction of travel (the horizontal line in FIGS. 1 to 5). It is explanatory drawing for calculating | requiring angle | corner (theta) 2 which a horizontal line makes). When the point Q5 of the cross head 13a extending in the horizontal direction and intersecting the surface of the rear platen 10 is Q6, the distance between the points Q1 and Q6 is A, and the distance between the points Q6 and Q5 is Y. If the angle between the line connecting point Q1 and point Q5 and the line connecting point Q1 and point Q2 (line of link L2) is β, it is the second for the triangle formed by points Q1, Q5 and Q2. Applying the cosine theorem, the angle β is β = cos ⁻¹ ((A ² + Y ² + L ^{2 2} −L 4 ² ) / (2 * L 2 * √ (A ² + Y ² )))
As required.

Therefore, the angle θ2 is expressed as follows. The angles ψ1 to ψ3 of each link are also expressed as follows.
θ2 = (π / 2) −β-tan ⁻¹ (Y / A)
ψ2 = θ2 + a
ψ3 = sin ⁻¹ ((L1 * sinψ2−B) / L3)
ψ1 = sin ⁻¹ ((A−L2 * sin (ψ2−a)) / L4)
On the other hand, as shown in FIG.
The force applied from the crosshead 13a to the link L4 of the toggle mechanism 13 is F1,
The crosshead movement direction component of the force F1 is Fch,
The reaction force that the movable platen 9 acts on the link L3 of the toggle mechanism 13 is F3,
The moving direction component of the movable platen 9 of the reaction force F3 is Fp,
The force F1 'applied to the link L4 and the link L2 applied to the pivot point Q2 between the link L4 and the link L2 is F1',
A force F3 'applied to the link L3 and a link L1 applied to the pivot point Q3 between the link L3 and the link L1 is F3',
Then, the following relationship is established.
F3 = Fp / cosψ3
F3 '= F3 * sin (ψ2 + φ3)
F1 = Fch / cosψ1
F1 '= F1 * sin (ψ1 + ψ2-a)
= Fch * sin (ψ1 + ψ2-a) / cosψ1
Accordingly, considering the moment around the pivot point Q1 where the toggle mechanism 13 is attached to the rear platen 10, the moment Mp on the movable platen side and the moment Mch on the crosshead side are as follows.
Mp = L1 * F3 '
Mch = L2 * F1 '
Since moments are balanced and equal, Mp = Mch.
L1 * F3 '= L2 * F1'
Therefore,
L1 * Fp * sin (ψ2 + ψ3) / cosψ3 = L2 * Fch * sin (ψ1 + ψ2-a) / cosψ1
Fch / Fp = (L1 * cosψ1 * sin (ψ2 + ψ3)) / (L2 * cosψ3 * sin (ψ1 + ψ2-a))
If the movable platen 9 is moved by ΔYp when the crosshead 13a is moved by ΔYch, the kinetic energy of the crosshead 13a is transmitted to the movable platen 9,
Fch * ΔYch = Fp * ΔYp
It is.
Therefore, since the speed gain G is ΔYp / ΔYch,
G = ΔYp / ΔYch = Fch / Fp
= (L1 * cosψ1 * sin (ψ2 + ψ3)) / (L2 * cosψ3 * sin (ψ1 + ψ2-a))
Since L1, L2, and a are predetermined constants and ψ1 to ψ3 are functions of the movement amount (position) of the crosshead, the speed gain G is a function of the position of the crosshead.

  The speed gain G is a function of the angles ψ1 to ψ3. As described above, the angle ψ1 and the angle ψ3 are functions of the angle ψ2, the angle ψ2 is a function of the angle θ2, and the angle θ2 is a function of Y representing the position of the crosshead. Therefore, the speed gain G is a function of the position of the crosshead, and eventually the rotational position of the mold opening / closing servomotor M4 that drives the crosshead.

  FIG. 6 is a diagram showing the speed gain G thus obtained and the inverse 1 / G of the speed gain as the acceleration pattern with respect to the position of the crosshead 13a.

  Since the position, speed, and acceleration of the crosshead 13a and the rotational position, speed, and acceleration of the mold opening / closing servomotor M4 are in a proportional relationship, the position of the crosshead 13a represented by the horizontal axis in FIG. Since the position of the open / close servo motor M4 can be set, the rapid change in speed and large acceleration of the movable platen 9 can be suppressed by controlling the acceleration of the mold open / close servo motor M4 with this acceleration pattern.

For example, when the mold opening / closing servo motor M4 is moving at the speed Vm, the movable platen 9 is moving at G * Vm obtained by multiplying the speed Vm by the speed amplification factor G. In this state, it is assumed that the mold opening / closing servomotor M4 is accelerated by ΔVm without considering the acceleration pattern. In this case, the speed of the movable platen 9 is G * (Vm + ΔVm).
The speed of the mold opening / closing servo motor M4 is
Vm changes to (Vm + ΔVm), and the amount of change is ΔVm,
The speed of the movable platen 9 is
It changes from G * Vm to G * (Vm + ΔVm), and the amount of change is G * ΔVm,
Thus, although the mold opening / closing servomotor M4 has a speed change of ΔVm, the movable platen 9 has a speed change amount of G * ΔVm, and if the speed gain G is large, it changes greatly. That is, the acceleration of the movable platen 9 may change greatly.

On the other hand, if the mold opening / closing servomotor M4 is accelerated using the acceleration pattern (1 / G),
The speed of the mold opening / closing servo motor M4 is
Vm changes to (Vm + ΔVm / G), and the amount of change is ΔVm / G,
The speed of the movable platen 9 is
G * Vm changes to G * (Vm + ΔVm / G), and the change amount is ΔVm,
Thus, the speed change amount becomes equal to the intended change amount ΔVm. That is, the speed of the movable platen 9 can be changed with the intended acceleration.

  In the above-described example, the speed amplification factor is obtained and the acceleration pattern is obtained as its reciprocal. However, the speed of the movable platen 9 is simply measured by actually measuring the speed of the movable platen 9 relative to the position of the mold opening / closing servomotor M4 or the crosshead 13a. It is good also as a pattern and it is good also considering the reciprocal number of this speed pattern as an acceleration pattern. However, in this case, since simply taking the reciprocal value becomes negative, the speed is offset by a predetermined amount, and the reciprocal number of the (speed + offset) pattern is used as the acceleration pattern. FIG. 7 is a diagram showing an acceleration pattern that is the reciprocal of the pattern of the actual speed with respect to the position of the crosshead 13a and the (speed + offset) pattern when the acceleration pattern is obtained based on the measured speed.

  The acceleration pattern curve with respect to the position of the mold opening / closing servomotor M4 (or crosshead 13a) obtained in this way is approximated by an approximate expression, and the mold opening / closing servomotor M4 (or crosshead 13a) is positioned based on this approximate function. The acceleration may be obtained and the acceleration / deceleration of the mold opening / closing servomotor M4 may be controlled.

  In the present embodiment, the acceleration with respect to the position of the mold opening / closing servomotor M4 corresponding to the acceleration pattern curve is set in a table format as an acceleration pattern table, and the acceleration of the mold opening / closing servomotor M4 is based on the acceleration pattern table. To control. FIG. 8 shows an example of the acceleration pattern table. The acceleration pattern curve is divided into three areas, and the acceleration of each area is set and stored. When the position P of the mold opening / closing servo motor M4 is from 0 to P (0), the acceleration is a (0), the position is from P (0) to P (1), the acceleration is a (1), and the position is from P (1). When the position P (2) is exceeded, that is, when the position P (1) is exceeded, the acceleration is set to a (2), and the acceleration pattern curve is approximated in three acceleration regions.

When the mold opening / closing servomotor M4 is controlled by the acceleration pattern stored in the acceleration pattern table, an example of the movement amount for each sampling period (movement command distribution period) commanded to the mold opening / closing servomotor M4 is shown. 9 shows.
At the start of movement, the acceleration is accelerated by a (0), and the movement amount in the commanded sampling cycle starts from “0”, and the movement amount obtained from the sampling cycle time and acceleration by a (0) sequentially. The mold opening / closing servomotor M4 is commanded while increasing. Then, when the position of the mold opening / closing servomotor M4 reaches the acceleration switching point P (0) where the acceleration set in the acceleration pattern table is switched from a (0) to a (1) during this acceleration, the acceleration is a ( 1) to accelerate. In this example, the target speed commanded by accelerating at this acceleration a (1) is reached, and the movement amount commanded in the sampling period becomes constant (the movement amount corresponding to the command speed), and thereafter the acceleration a (1 ) Starts deceleration, and when the position of the mold opening / closing servomotor M4 reaches the acceleration switching point P (1) during the deceleration, the acceleration is switched to a (2), and the deceleration is stopped at the commanded target position. Thus, the amount of movement of the sampling period is determined and commanded.

  FIG. 10 is a flowchart of acceleration / deceleration control processing executed by the CNC CPU 40 of the control device (numerical control device) 30 in the present embodiment. The acceleration / deceleration control process of this embodiment will be described with reference to the acceleration pattern table shown in FIG. 8 and the movement amount for each sampling period (distribution period) shown in FIG. 9 together with this flowchart.

  When the command speed Vc and the command position Pe are commanded, for example, in the present embodiment, the mold clamping completion position is commanded as the command position Pe, and the command speed Vc in the mold closing process is commanded. The mold opening / closing servomotor M4 is driven, and the mold closing process is started. First, the CNC CPU 40 sets an index j indicating a position and acceleration reading point from the acceleration pattern table to “0”, and sets the current position P and the speed V to “0” (step S1). The acceleration a (j) (= a (0)) stored at the position indicated by the index j is read (step S2), and the processing after step S3 is executed every sampling cycle (distribution cycle).

The current position P is subtracted from the commanded target position Pe to obtain the remaining movement amount Pr (step S3), and it is determined whether the remaining movement amount Pr is "0" (step S4). A movement amount “V ² / 2a (j)” required to decelerate from V to a speed of 0 at the current acceleration a (j) is obtained, and the movement amount is larger than the remaining movement amount Pr obtained in step S3. (Step S5). When the remaining movement amount Pr is smaller than the movement amount “V ² / 2a (j)” required to decelerate at the current acceleration and become zero, the process proceeds to step S17 to start deceleration. When the movement amount Pr is larger than the movement amount “V ² / 2a (j)” required until the speed becomes zero, the process proceeds to step S6 and acceleration is performed. At first, since the speed V is “0”, the movement amount required until the speed becomes 0 is “V ² / 2a (j) = 0”, the process proceeds to step S6, and the current speed V is The read acceleration a (j) is added to obtain the accelerated speed V. It is determined whether the obtained speed V exceeds the command speed Vc. If not, the process proceeds to step S9, where the obtained speed V is multiplied by the sampling period time s, and the movement amount ΔP (= V * s) is obtained, and it is determined whether the movement amount ΔP is larger than the remaining movement amount Pr obtained in step S3. If it is not larger, the process proceeds to step S12. If it is larger, ΔP> Pr is the command position Pe. The movement amount ΔP is set to the remaining movement amount Pr (step S11). In step S12, the movement control amount of the mold opening / closing servomotor M4 is set using the movement amount ΔP as a movement command amount. (Step S12).

  Then, this commanded movement amount ΔP is added to the current position P to update the current position P (step S13). It is determined whether or not the updated current position P is larger than the position P (j) indicated by the value of the index j in the acceleration pattern table. If not, the process returns to step S3, and the processes after step S3 are executed every sampling period. To do.

  In the example shown in FIGS. 8 and 9, first, j = 0, P = 0, and V = 0. In step S2, the acceleration of a (0) is read, and in step S6, V = V + a (0 ) = A (0) speed is obtained, and in step S9, a movement amount ΔP = V * s = a (0) * s is obtained and output as shown in FIG. The movement amount increased by the acceleration from the speed 0 is output in the first sampling cycle. Thereafter, the processing after step S3 is performed, and the movement amount corresponding to the acceleration a (0) is sequentially increased and output every sampling cycle. The position P obtained by integrating the output movement amount ΔP in step S13 is the acceleration switching point P (j) (the current index j value (initially j = 0) set in the acceleration pattern table ( At first, it is determined in step S14 whether P (j) = P (0)) has been exceeded. If it has exceeded, index j is incremented by 1 (step S15), and acceleration a (j corresponding to the index j is determined from the acceleration pattern table. ) (Step S16), and the process proceeds to step S3. In the example shown in FIGS. 8 and 9, it is detected that the acceleration switching position P (0) has been reached while accelerating at the acceleration a (0), and the next (j = 1) acceleration a (1) is detected. ) Is read out, and the processes in and after step S3 are performed. From this, the velocity is increased by the acceleration a (1) in the sampling period, and the amount of movement increased by the amount of acceleration a (1) (a (1) * s) is obtained and output in step S9. become.

When it is determined that the speed V has exceeded the commanded speed Vc (step S7) by sequentially increasing the acceleration speed, the speed V is limited to the command speed Vc (step S8).
The example shown in FIGS. 8 and 9 shows a case where the speed V reaches the command speed Vc when the index j in the acceleration pattern table is “1” and the speed is increasing at the acceleration a (1). After reaching the command speed Vc, a movement amount ΔP = V * s = Vc * s corresponding to the command speed Vc is output for each sampling period.

Thus, the movement command is output, and in step S5, the remaining movement amount Pr is decelerated from the current speed V at the current acceleration a (j), and the movement amount “V” required to decelerate until the speed becomes zero. ^{When 2} / 2a (j) "or less, that is, when the remaining movement amount Pr is equal to or less than the necessary movement amount until it is decelerated at the current speed and acceleration and stopped, the process proceeds to step S17. Then, the current acceleration a (j) is subtracted from the current speed V to obtain a decelerated speed V, and the process proceeds to step S9.

  In the example shown in FIGS. 8 and 9, when the index j = 1, the acceleration a (j) = a (1), and the speed is limited to the command speed Vc to obtain the movement amount, the remaining movement amount Pr Shows an example when the amount of movement is smaller than the amount of movement required until the vehicle is decelerated at the current speed and acceleration and stopped, and the amount of movement output as a movement command is acceleration a (j) for each sampling period. = The movement amount reduced by a (1) is output.

  Further, if it is determined in step S14 that the current position P has exceeded the acceleration switching position P (j) = P (1), the index j is incremented by 1 (in this case, 2), and the acceleration is determined from the acceleration pattern table. a (j) (in this case, a (2)) is read out, and the acceleration is subsequently decelerated. When it is determined that the remaining movement amount Pr is 0 (step S4), this process is terminated.

  As described above, the present invention can change the rate of increase or decrease in speed by switching to another acceleration even while increasing the speed at a certain acceleration, or even while decelerating at a certain acceleration. In addition, the speed can be changed at a designated acceleration even when the motor is driven at a constant speed.

  When the motor speed is kept constant before the speed V reaches the command speed Vc, if the acceleration a (j) is set to “0”, the speed does not change and the current speed is maintained. Will be. In this case, the determination in step S5 is “Yes”, and in step S17, the acceleration of 0 is subtracted from the current speed V, and the movement amount is obtained without changing the speed V. However, it is determined whether the remaining movement amount can decelerate. Since it cannot be performed, the section where the acceleration is set to “0” needs to be performed in a section where the remaining movement amount is guaranteed.

In the embodiment described above, the present invention has been described as an example implemented in the mold closing process of the mold clamping mechanism of the injection molding machine. However, in the mold opening process, the same acceleration / deceleration control method of the present invention is applied and controlled. It may be. When the machine movable part (movable platen) is driven by a servo motor via a speed amplification mechanism such as a toggle mechanism, the acceleration is changed according to the position of the servo motor based on the acceleration pattern as described above. By processing, it is possible to control the speed acceleration and speed fluctuation of the machine movable part (movable platen) to the intended ones.

The present invention can also be applied to cases where acceleration / deceleration control is desired by changing the acceleration in accordance with the position of the machine movable part even when a speed amplification mechanism such as a toggle mechanism or a clamp mechanism is not used. is there.
For example, as described above, in the injection process of the injection molding machine, in order to control the flow of resin in the mold, the injection servo that drives the injection screw according to the injection screw position of the movable part that performs injection The acceleration / deceleration control of the present invention may be applied so as to perform acceleration and deceleration by changing the acceleration of the motor. In this case, depending on the viscosity of the resin, the mold shape, and the filling state of the resin in the mold, the injection screw position (servo for injection) is taken into account by increasing or decreasing the injection speed (resin filling speed in the mold). An acceleration pattern of acceleration corresponding to the motor M1) is set, and based on the pattern, the injection speed is controlled by controlling the speed of the injection servo motor M1 as in the above-described embodiment. In particular, even when the injection speed is being accelerated or decelerated at a certain acceleration, it can be accelerated or decelerated at another acceleration, so that the speed control can be made fine and optimal injection control can be performed.

It is a schematic diagram of an electric injection molding machine as one embodiment to which the acceleration / deceleration control method of the present invention is applied. It is a figure which shows the state which extended the link of the toggle mechanism in the same embodiment. It is explanatory drawing for analyzing the position and speed of the crosshead of a toggle mechanism, and the position and speed of a movable platen in the embodiment. It is explanatory drawing for analyzing the position and speed of the crosshead of a toggle mechanism, and the position and speed of a movable platen similarly. It is explanatory drawing for analyzing the position and speed of the crosshead of a toggle mechanism, and the position and speed of a movable platen similarly. In the same embodiment, it is the figure represented as a speed gain by a toggle mechanism, and an acceleration pattern. In the embodiment, the speed of the movable platen relative to the position of the crosshead of the toggle mechanism is measured to obtain a speed pattern of the movable platen, and the actual speed of the crosshead position when the reciprocal of this speed pattern is obtained as the acceleration pattern. It is a figure showing a pattern and an acceleration pattern. It is an example of the acceleration pattern table which set and memorize | stored the acceleration with respect to the position of the servomotor for mold | die opening / closing in the embodiment. FIG. 9 is an explanatory diagram for explaining an example of a movement amount for each sampling period (movement command distribution period) when the mold opening / closing servomotor is controlled with the acceleration pattern stored in the acceleration pattern table shown in FIG. 8. It is a flowchart of the acceleration / deceleration control process in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection cylinder 2 Nozzle part 3 Injection screw 8 Fixed platen 9 Movable platen 10 Rear platen 11 Mold 13 Toggle mechanism 13a Crosshead 30 Controller M1 Injection servo motor M2 Screw rotation servo motor M3 Projection servo motor M4 Type opening / closing servo motor

Claims (4)

It is equipped with a speed amplification mechanism that changes the speed amplification factor according to the position, and the movable part of the machine is driven and controlled by the servo motor via the speed amplification mechanism based on a movement command from the control device. In the acceleration / deceleration control method for controlling
The acceleration corresponding to the position of the servo motor that is moving to the target position according to the movement command is obtained from the reciprocal of the speed amplification factor of the speed amplification mechanism and set in the control device in advance as an acceleration pattern. A method for controlling acceleration / deceleration of a machine movable portion, which controls the speed by changing the acceleration according to the position of the servo motor based on the acceleration pattern. It is equipped with a speed amplification mechanism that changes the speed amplification factor according to the position, and the movable part of the machine is driven and controlled by the servo motor via the speed amplification mechanism based on a movement command from the control device. In the acceleration / deceleration control method for controlling
The controller corresponding to the position of the servo motor that is moving to the target position according to the movement command is measured in advance according to the position of the movable part and is obtained from the reciprocal of the measured speed as an acceleration pattern in advance. An acceleration / deceleration control method for a machine-movable part that controls the speed by changing the acceleration according to the position of the servo motor based on the acceleration pattern during the servo motor drive .   The acceleration / deceleration control method for a machine movable unit according to claim 1 or 2, wherein an acceleration corresponding to a position is stored in a table in the acceleration pattern.   The acceleration / deceleration control method for a machine movable unit according to claim 1 or 2, wherein the set acceleration pattern is a function indicating a relationship of acceleration corresponding to a position.

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