JPH0447917A - Driving mechanism in injection molder - Google Patents

Abstract

PURPOSE:To promote the equalization of time-average utilization of equipments and realize the utilization of general-purpose motors and easy constitution of machines consisting of movable part by a method wherein the transmission objects of driving means are changed over through a first and a second gears by a first and a second transmitting means. CONSTITUTION:In a metering and back pressure applying process, a clutch 42 is turned ON and a screw 40 is rotated through the rotation of a motor 48 so as to accumulate molten resin in a cylinder 50, resulting in shifting a stand 54 on members 56a and 56b by means of the pressure of said resin. At this time, a clutch 42a is turned OFF, resulting in transmitting no rotation of the motor 49 to a gear 45. In an injecting and dwelling process, the clutch 42 is turned OFF and the clutch 42a is turned ON so as to synchronize the rotation of the motor 48 through gears 44 and 43 the clutch 42a and a gear 45 with the rotations of motors 60a and 60b through gears 68a and 68b at both the sides of a gear 45. Thus, the advancing force of the metering and injecting stand 54 is obtained under the condition that the rotations of the two motors 60a and 60b and the rotation of the motor 48 are summed up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive mechanism for suitably performing the steps of metering, back pressure, injection and pressure holding in a plastic injection molding machine.

[Prior art] Conventionally, in the metering, back pressure, injection and pressure holding processes of an electrically driven injection molding machine, the metering process is executed by a first motor, and the back pressure, injection and pressure holding processes are performed by a first motor. The process is executed by another second motor.

An example of this prior art is shown in FIG.

That is, in the metering/back pressure process, the metering/injection screw 2 is connected to the motor 6 via the coupling 4, and as the motor 6 rotates, the metering/injection screw 2 rotates and the resin is metered. It will be done. The rotation of the motor 6 is controlled by a feedback signal obtained by a position detector 10 attached to the motor 6 to a specified rotation speed via a controller (not shown).

Then, the metering/injection screw 2 rotates to measure the resin, the molten resin is accumulated in the metering/injection cylinder 12, and the resin pressure of the accumulated molten resin causes the metering/injection screw 2, the coupling 4, A force acts to move the motor 6 and the metering/injection table 14 backward, causing the cylinder table 20 to move backward as a whole.

At this time, each ball screw 30a is connected to two ball screws 24a and 24b mounted under the measuring/injection table 14 via couplings 28a and 28b of two motors 26a and 26b, 30b, a force is exerted to prevent the metering/injection table 14 from retreating. That is, back pressure can be applied by rotating the two motors 26a and 26b synchronously. The rotations of the two motors 26a, 26b are synchronously controlled with torque specified by a controller (not shown) by feedback signals obtained from respective position detectors 32a, 32b attached to these motors.

In the injection molding machine, in the injection/holding process, the molten resin accumulated in the metering/injection cylinder 12 during the metering/backpressure process is clamped in advance by moving the metering/injection screw 2 forward. The resin mold 36 is filled with the resin.

At this time, since the metering/injection screen L-2 has a backflow prevention ring attached to its tip, it will not be reversed due to backflow caused by the filling pressure of the molten resin. At this time, the motor 6, which is connected to the metering/injection screw 2 through the coupling 4, does not need to rotate, and a controller (not shown) is activated by the feedback signal obtained from the position detector 10 attached to the motor 6. Since the motor 6 does not need to be controlled to a specified rotation speed via the motor 6, the motor 6 is in a controlled-out, ie, free state.

Now, in order to move the metering/injection screw 2 forward, for the same reason as explained in the metering/back pressure process above, the two motors 26a and 26b are synchronized, and the two motors 26a and 26b are connected to each other via the respective couplings 28a and 128b. The ball screws 30a and 30b that are engaged with each other are rotated in synchronization, and the weighing and injection table 14 is advanced with respect to the two ball screws 24a and 24b that are attached under the weighing and injection table 14. Two motors 26a,
26b should be rotated in synchronization. At this time, the rotation of the two motors 26a, 26b is controlled by a feedback signal obtained from each position detector 32a, 32b, according to a preset forward speed pattern of the metering/injection screw 2 from a controller (not shown), i.e. , are synchronously controlled at a specified rotation speed corresponding to the injection pattern.

In this way, the molten resin accumulated in the metering and injection cylinder 12 can be injected and filled into the resin mold. However, simply injecting and filling in this way tends to cause problems such as pulling when the resin mold and resin are cooled, and molding defects are likely to occur. Therefore, after injection and filling, pressure is continued to be applied to the molten resin injected and filled into the resin mold 36 in order to prevent the above-mentioned problems. In other words, holding pressure is applied. this is,
Two ball nuts installed under the weighing/injection table 14) 24 a.

24b to the metering and injection table 14 via respective ball screws 30a, 30b which are coupled via respective couplings 28a, 28b to two motors 26a, 26b.
This is achieved by rotating the two motors 26a and 26b synchronously so as to exert a force that moves the motor forward. The rotation of the two motors 26a, 26b is controlled by the feedback signals obtained from the respective position detectors 32a, 32b attached to these motors, and the forward movement pattern of the metering/injection screw 2 is set in advance by a controller (not shown), that is, It is controlled in synchronization with a specified torque corresponding to the holding pressure pattern.

[Problem to be solved by the invention] When an injection molding machine is electrically driven in this way, it is difficult to measure and
In the back pressure, injection and pressure holding processes, the metering process is performed by the motor 6, and the back pressure, injection and pressure holding processes are performed by the other motors 26a and 26.
I am doing it with b.

In this case, the following may be considered as an example of the motor capacity required in each of the above steps.

Metering...28kW Back pressure...8kW Injection...
・40kW Holding pressure...90kW In this example, the metering process is performed by motor 6, and the back pressure, injection, and pressure holding processes are performed by other motors 26a and 26b.The motor capacity is selected as follows. I can think of things.

Measuring motor capacity: 28kW Back pressure/Injection/
Pressure holding motor capacity: 90 kW (45 kW x 2) Also, in this example, the required power supply capacity for the entire motors 6.26a and 26b and the motor control power converter is assumed to have an overall efficiency of 80%. If stipulated, the following may be considered:

Motor power supply capacity: 147.50kW Motor control power converter power supply capacity: 140.63kW If the above is collectively expressed in a systematic diagram, it is as shown in Figure 4, and if expressed over time, it is as shown in Figure 4. It will look like Figure 5.

Looking at the motor here, the minimum/maximum required capacity...36/90 kW installed capacity
...126kW, and looking at the power converter for motor control, the minimum/maximum required capacity...45/112.5kW, and the installed capacity...147.5kW. In other words, about 1/3 to 2/3 of the installed capacity is always in a dormant state on a time-average basis. This means that the equipment is not being utilized effectively and is not economical.

Also in FIG. 3, motor 6.26a.

26b is directly coupled to the drive, but in this case, considering the motors 6.26a, 26b, it can be seen as follows.

Measuring motor: 28kW, 40Orpm Back pressure/injection/pressure holding motor: 45kW, 400rpm The following are generally considered as standard (general purpose) motor rating ranges.

Rated capacity...0.5kW~15kW Rated rotation speed...
-1000 rpm to 3000 rpm The following are generally considered as the range of industrial standard motor ratings.

Rated capacity: 0.75kW to 55kW Rated rotation speed:
...1500 rpm to 1800 rpm The above configuration has a simple mechanical configuration and is inexpensive, but
It greatly depends on various conditions of back pressure, injection, and holding pressure processes.
This makes it impossible to select a motor from a range of industrial standard motors, resulting in increased costs.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and its purpose is to promote leveling of the time-averaged usage of equipment and improvement of efficiency, and to enable the use of general-purpose motors.
Furthermore, it is an object of the present invention to provide a drive mechanism for an injection molding machine that allows the movable part mechanism to be easily constructed and is manufactured at a low cost as a result.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the drive mechanism in the injection molding machine of the present invention includes: a metering/injection screw; a first drive mechanism fixed to a displaceable metering/injection table; a first drive means for rotationally driving a shaft; a first gear connected to the first drive shaft; and a second drive means fixed to the weighing/injection table.
a second drive means for rotationally driving the drive shaft of the meter; a second gear connected to the second drive shaft;
a first transmission means that connects the injection screw and the first drive shaft as necessary and transmits the rotational driving force of the first drive shaft to the metering/injection screw via the first gear; disposed between the first gear and the second gear, connects the first drive shaft and the second drive shaft as necessary, and transfers the rotational driving force of the first drive shaft to the second drive shaft. a second transmission means for transmitting data to the shaft; and a displacement means connected to the second drive shaft and displacing the metering/injection table toward the metering/injection screw based on the rotational driving force of the second drive shaft. It is characterized by comprising the following.

[Function] In the injection molding machine of the present invention configured as described above, the drive mechanism transmits data to the drive means through the first and second gears during the metering/back pressure and injection/pressure holding processes. using the first and second transmission means;
The maximum required capacity/installed capacity and the utilization rate of the minimum/maximum required capacity/installed capacity of the power converter for controlling the drive means in terms of time are leveled, and the versatility of the drive means used is achieved. Furthermore, for movable parts other than the metering/injection cylinder and the metering/injection screw, a lightweight, easy-to-configure injection table and displacement means are used. This simplifies the configuration of the movable part mechanism and allows the use of a general-purpose motor.

[Example] Next, a preferred example of a drive mechanism in an injection molding machine according to the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1a and 1b show an injection molding machine to which the drive mechanism of the injection molding machine of this embodiment is applied.

This injection molding machine consists of a metering/injection screw 40 that processes metering, injection, and pressure holding processes, and a clutch 42 connected to this screw. The clutch 42 includes a motor 48 connected via a gear 43 and a gear 44 disposed within a gear box 52. Furthermore, a metering and injection cylinder 50 is provided which engages the metering and injection screw 40 and in which resin is accumulated.

These components are arranged on a movable weighing/injection table 54, which has sliding members 56a, 56
b, and is configured to move on the base 58.

Furthermore, a clutch 42a connected to a gear 43 and a gear 45 are provided on the metering/injection table 54. Also,
Couplings 46a, 46b and ball screws 64a, 64b connected thereto, the ball screw 64a
, 64b are screwed into two ball nuts (62a, 62b) fixed to the metering/injection cylinder 50.

Gears 68a and 68b are connected to the couplings 46a and 46b via shafts, respectively, and these gears 68
a and 68b are connected to drive shafts of motors 60a and 60b.

The motors 48, 60a, 60b are provided with a position detector 72 for controlling the rotation speed or torque specified by a controller (not shown) via a feedback signal.
．． 72a and 72b are provided.

Further, a cylinder stand 74 is fixed to the base 58, and the measuring/injection cylinder 50 is mounted on the cylinder stand 74 with a ball screw 64a screwed into the ball holes 62a and 62b.
, 64b.

Note that a resin molding die 80 is attached to a fixing member (not shown) at the tip of the metering/injection cylinder 50.

The operation in the above configuration will be explained below.

In the metering/back pressure process, the metering/injection screw 40 is coupled to a motor 48 via a clutch 42 and gears 43,44;
In the ON state, both end shafts are connected. Therefore, when the motor 48 rotates, the metering/injection screw 40 rotates, and the resin is metered. The rotation of the motor 48 is controlled by a feedback signal obtained from an attached position detector 72 to a rotation speed specified by a controller (not shown).

Then, the metering/injection screw 40 rotates to measure the molten resin, and the molten resin is accumulated in the metering/injection cylinder 50, and the metering/injection screw: L-40 is caused by the resin pressure of the accumulated molten resin. , the gear box 52 and the weighing/injection table 54 are moved backward, and the weighing/injection table 54 moves on the sliding members 56a, 56b provided on the base 58. In this case, the two motors 60a and 5Qb are attached to the metering/injection table 54, and in the metering/back pressure process, the clutch 42a is OFF and the shafts at both ends are separated, so the motor 48 rotates. is not transmitted to gear 45. This cylinder stand 74 on the t1 base 58
62a, 6
2b to two motors 60a160b with respective gears 6
8a, 68b through respective ball screws 64a, 64b connected via respective couplings 46a, 46b, a force is exerted to prevent said metering/injection table 54 from retreating. That is, two motors 60a, 60b
Back pressure can be applied by rotating synchronously on both sides of gear 45 through respective gears 68a, 68b. Is the rotation of the two motors 60a and 60b controlled by the attached position detectors? The torque is controlled by a feedback signal obtained by 2a and 72b to a torque specified by a controller (not shown).

In the injection/pressure holding process of an injection molding machine, the molten resin accumulated in the metering/injection cylinder 50 during the metering/backpressure process is transferred to the resin that has been clamped in advance by moving the metering/injection screw 40 forward. The inside of the molding die 80 is filled.

At this time, since a backflow prevention ring is attached to the tip of the metering/injection tube 'J, -40, it will not be reversed due to backflow due to the filling pressure of the molten resin. Measurement·
Injection screw 40, clutch 42, gear 43 and gear 4
In this case, the motor 48 coupled via the motor 48 does not need to rotate, and the feedback signal obtained by the position sensor 72 attached to the motor 48 allows the motor 48 to rotate at a specified rotation speed via a controller (not shown). The motor 48 does not need to be controlled, and the motor 48 may be controlled out, that is, in a free state. As a result,
Both end shafts can be separated with the clutch 42 in the OFF state.

Here, in order to advance the metering/injection screw 40,
For the same reason as explained in the weighing and backpressure process above,
The two motors 60a and 60b are rotated. That is,
Each gear 68a168b and couplings 46a, 46
Each ball screw 64a, 6 connected via b
4b, two ball nuts attached to the inside of the cylinder stand 74 on the base 58) 62
The two motors 60a and 60b may be rotated so as to exert a force that moves the metering/injection unit 54 forward from the motors 60a and 62b. At this time, the motor 48 is in a free state, so the clutch 42a is turned on to connect both ends, and the rotation of the motor 48 is transferred to the two motors 6 through the gear 44, gear 43, clutch 42a1 and gear 45.
Both sides of the gear 450 are rotated in synchronization with the rotation of the gears 0a and 60b through the gears 68a and 68b, respectively. Therefore, the force for advancing the metering/injection table 54 is obtained by the sum of the rotations of the two motors 60a and 60b and the rotation of the motor 48. In this case, two motors 60a,
The rotation of 60b is caused by position detectors 72 attached to each
a,? With the feedback signal obtained by 2b,
Further, the rotation of the motor 48 is controlled by a feedback signal obtained from a position detector 72, and the metering/injection screw 4 is controlled in advance by a controller (not shown).
The rotation of the motor 48 is performed via the gears 44, 43, clutch 42a, and gear 45 at the rotation speeds specified for the two motors 60a and 60b and the motor 48, respectively, corresponding to the forward speed pattern of 0, that is, the injection pattern. The rotation of the two motors 60a, 60b is transmitted through the gears 68a, 6, respectively.
Both sides of gear 450 are controlled to be synchronized with the rotation via gear 8b.

In this way, the molten resin accumulated in the metering and injection cylinder 50 can be injected and filled into the resin mold. However, simply injecting and filling in this way tends to cause problems such as pulling when the resin mold and resin are cooled, and molding defects are likely to occur. Therefore, injection,
After filling, the molten resin is injected into the resin molding mold 80 and pressure is further continued to be applied to the filled molten resin in order to prevent the above-mentioned problems. In other words, holding pressure is applied. The two motors 6 are connected to pole nuts 62a and 62b attached to the inside of the cylinder stand 74 on the base 58.
0a, 5Qb so as to exert a force to advance the metering/injection table 54 through respective ball screws 64a, 64b which are connected to respective gears 68a, 68b and respective couplings 46a, 46b. Motor 60a, 6
This can be achieved by rotating 0b. At this time, as in the case described above, the motor 48 is in a free state, so the clutch 42 is in an OFF state and both ends of the shaft are separated, and the clutch 42a is in an ON state and both ends are connected. The rotation of the motor 48 via the gear 44, the gear 43, the clutch 42a1 and the gear 45 is rotated on both sides of the gear 45 in synchronization with the rotation of the two motors 60a160b via the respective gears 68a and 68b. As a result, the force that moves the metering/injection table 54 forward is
This is obtained by the sum of the rotations of the two motors 60a and 60b and the rotation of the motor 48. In this case, the rotation of the two motors 60a, 60b is
Each position detector 72a, ? The feedback signal obtained by 2b also causes the motor 48
The rotation of the position sensor 72 attached to the motor 48
Based on the feedback signal obtained, the two motors 60a, 60b and motor 4 are activated in response to the forward pressure cover turn of the metering/injection screw 40, that is, the pressure holding pattern, which is preset by a controller (not shown).
Gear 4 of the rotation of motor 48 with the torque specified in each 8
4, gear 43, clutch 42a, rotation via gear 45, rotation of two motors 60a, lOb, each gear 6
Both sides of the gear 45 are controlled to be synchronized with the rotation via the gears 8a and 68b.

Two motors 60a, 60b and motor 4 used in the present invention
As an alternative to 8, a hydraulic motor can also be used. Also, gear 43, gear 44, gear 45, gear 68
As an alternative to a and 68b, it can also be constructed using a boolean, two groups of pulleys, and a belt.

In the embodiments described above, the following motor capacities are considered necessary for each process.

Metering...28kW Back pressure...8kW Injection...
40kW Holding pressure: 90kW In this embodiment, the processes of metering, injection, and holding pressure are performed by one motor 48, and the processes of back pressure, injection, and holding pressure are performed by the other two motors 60a and 60b.
The motor capacity can be selected as follows.

Motor capacity for metering, injection, and pressure holding: 30 kW Motor capacity for back pressure, injection, and pressure holding: 60 kW (2 units of 30 kW x 2) In addition, the motors 48, 60a, 60b, and
Assuming that the overall efficiency of each of these power converters for motor control is defined as 80%, the following power supply capacity is considered necessary for these motor control power converters.

Motor power supply capacity: 112.50kW Motor control power converter power supply capacity: 140.63kW The above information is summarized in Figure 2. Note that the time course is the same as in FIG. 5.

Looking at the motor here, the minimum/maximum required capacity...36/90 kW installed capacity
...90kW, and looking at the power converter for motor control, the minimum/maximum required capacity...45/112.5kW, and the installed capacity...112.5kW. As a result, the equipment capacity will no longer be idle on a time-average basis. In addition, the equipment utilization rate has increased from 31/76% to 40/100.
%, and the installed capacity can be reduced to about 3/4.

We will consider the motors 48, 60a and 60b in such a case, and also consider the gears 44, 43, 45, and 6.
Considering 8a and 68b, the following can be considered from the above contents.

Measuring motor: 30kW, 1500rpm Back pressure/injection/pressure holding motor: 30kW, 1500rpm Total gear ratio of gears 44 and 43: 4/15 Gear ratio of gears 43 and 45: 1 /1 Gear ratio of gear 45, gears 68a, 68b...1/1 Gear ratio of gears 68a, 68b...4/15 And the standard (general purpose) motor rating range is generally as follows. I can think of things.

Rated capacity...0.5kW~15kW Rated rotation speed...
- 11,000 rpm to 3,000 rpm The following are generally considered as the range of industrial standard motor ratings.

Rated capacity: 0.75kW to 55kW Rated rotation speed:
...1500 rpm to 1800 rpm With the above configuration, the motor selection can be made from the range of industrial standard motors without depending greatly on the various conditions of the back pressure, injection, and pressure holding processes due to the plastic injection molding conditions. You will be able to choose.

In addition, in the weighing/backpressure, injection/holding/backpressure, and injection/holding processes of injection molding machines, the movable parts other than the metering/injection cylinder and metering/injection screw are replaced with sliding members, ball screws, and ball nuts. By configuring this, it is possible to easily configure the mechanism of movable parts other than the metering/injection cylinder and the metering/injection screenie.

[Effects of the Invention] As described above, according to the drive mechanism in the injection molding machine of the present invention, the minimum/maximum required capacity and installed capacity of the motor and the minimum/maximum required capacity and installed capacity of the motor control power converter can be improved. The usage rate over time has been leveled, improving equipment utilization efficiency and making it possible to use general-purpose motors. By constructing the movable parts of the mechanism other than the metering/injection cylinder and the metering/injection screenie with, for example, a sliding member, a ball screw, or a pole nut, there is an advantage that the structure of the mechanism of the movable parts can be simplified. Further, by selecting the gear ratio, it is possible to use a desired general-purpose electric motor, and the manufacturing cost can be reduced.

[Brief explanation of the drawing]

FIG. 1a is a plan view showing the configuration of an embodiment of the drive mechanism in the injection molding machine of the present invention, FIG. 1 is a side view of the embodiment shown in FIG. 1a, and FIG. Figure 3a is a plan view showing the configuration of the drive mechanism in a conventional injection molding machine, and Figure 3a is a diagram used to explain the power required for the drive mechanism in such an injection molding machine Figure 4 is a side view of the drive mechanism in an injection molding machine. Figure 4 is a diagram used to explain the required power of the drive mechanism in a conventional injection molding machine. Figure 5 is a diagram showing the required power of the drive mechanism in an injection molding machine over time. It is a figure provided for explanation. 40...Measuring/injection screw 42.42a...Clutch 43.44.45...Gears 46a, 46b...Coupling 48...Motor 50...Measuring/injection cylinder 52...Gear Box 54...Measuring/injection table 56a, 56b...Sliding member 58...Base 60a, 60b...Motor 62a, 62b...Pole nut 64a, 64b...Ball screw 68a, 68b... Gear 72.72a, 72kl" position detector 74...Cylinder stand 80...Resin molding mold FIG, 2

Claims (1)

[Claims] (1) A metering/injection screw, a first drive means fixed to a displaceable metering/injection table and rotationally driving a first drive shaft, and a first gear connected to the first drive shaft. , said weighing・
a second drive means fixed to the injection table and rotationally driving a second drive shaft; a second gear connected to the second drive shaft;
a first transmission means that connects the injection screw and the first drive shaft as necessary and transmits the rotational driving force of the first drive shaft to the metering/injection screw via the first gear; disposed between the first gear and the second gear, connects the first drive shaft and the second drive shaft as necessary, and transfers the rotational driving force of the first drive shaft to the second drive shaft. a second transmission means for transmitting data to the shaft; and a displacement means connected to the second drive shaft and displacing the metering/injection table toward the metering/injection screw based on the rotational driving force of the second drive shaft. A drive mechanism in an injection molding machine, comprising: and.