JPH05345337A - Electrically-driven injection molding machine - Google Patents

Abstract

PURPOSE:To conduct complete control in spite of a structure being inexpensive and compact. CONSTITUTION:In a injection step, a spline-receiving member 30 is fixed by connecting a nail 37 with a nail 39 by an actuator 36, and a nut member 15 is connected to a sleeve member 9 by applying an, excess current to an electromagnetic powder clutch 40. In this state, the rotation of a motor 5 is transmitted to the nut member 15 to advance a screw 19. In a plasticization step, a ball screw 25 is rotated through the spline-receiving member 30 with the nail 37 and a nail 11 connected each other, and the capacity of torque transmitted to the nut member 15 is controlled by the powder clutch 40. In this state, the powder clutch 40 slips and retreats while rotating the screw corresponding to the excessive back-pressure from the screw over the torque capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric injection molding machine, and more particularly to a drive device for rotating and moving a screw during plasticization and injection.

[0002]

2. Description of the Related Art Conventionally, as an injection molding machine, a plastic material is melted and weighed by reciprocating while rotating a screw, and then the rotation of the screw is stopped and the resin is advanced to inject a molten resin into a mold. The one to be filled is known as an in-line screw system, and one that uses two electric motors arranged in series in the axial direction as means for driving the screw is disclosed in, for example, JP-A-60-
No. 132721 and Japanese Patent Laid-Open No. 61-266218.

An injection molding machine (electric injection molding machine) using the electric motor includes a screw forward / backward moving motor and a screw rotating motor, and the rotating motor is connected to the screw as a male screw. The motor for forward / backward movement is connected to the portion so that it can slide only, and is connected to the female screw portion that is screwed into the male screw portion.

Then, by rotating the screw rotation motor to rotate the male screw portion and restricting the rotation of the female screw portion, the screw is retracted while rotating to melt and measure the resin. With the rotation of the screw portion stopped, the forward / backward moving motor is rotated to rotate the female screw portion, thereby moving the screw forward and injecting the resin.

[0005]

The above-mentioned conventional electric injection molding machine requires two electric motors arranged side by side in the axial direction of the screw, including a driver for driving and controlling each of these electric motors. However, the structure becomes extremely expensive and the structure becomes long in the axial direction.

Further, since it is necessary to control two electric motors for rotation and forward / backward movement, the control is extremely complicated and troublesome, and it is difficult to obtain a desired speed and pressure. Particularly, the screw is rotated. At the same time, during plasticization in which the pressure of the resin recedes, a peak of excessive pressure tends to occur.

Therefore, the present invention provides an electric injection molding machine that melts, measures, and injects resin with a single electric motor, and has an inexpensive and compact structure, but that is easy to control. With the goal.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and supports a screw (19) in a heating cylinder (17), retracts the screw while rotating, and rotates the screw. In an injection molding machine having a drive unit (U) that stops and advances, an electric motor (5) arranged in a cylindrical casing (1) and a sleeve that rotates integrally with a rotor (3) of the electric motor. The member (9), the spline receiving member (30) engaged with the spline (26) connected to the screw (19), and the male screw (25) connected to the screw (19) are screwed together. Female screw member (15) and the spline receiving member (30,
Switching means (38, 36) capable of selectively engaging the fixed member (37) such as the casing with the fixed member (1, 39) or the sleeve member (9, 11); and the sleeve member (9).
A torque control means (40) capable of controlling the torque transmitted from the female screw member (15) to the female screw member (15), and the spline receiving portion (30, 37) is fixed to the fixing member (1, 39) based on the switching means. , The screw (19) is moved forward by transmitting the rotation of the sleeve member (9) to the female screw member (15), and the spline receiving member (30, 37) is moved to the sleeve. The screw (19) is controlled by restricting the torque transmitted from the sleeve member (9) to the female screw member (15) based on the torque control means (40) in a state of being engaged with the members (9, 11). It is an electric injection molding machine characterized by being retracted while rotating.

As an example, the torque control means comprises an electromagnetic powder clutch (40).

Further, the spline (26) and the male screw (25) are formed on a single screw shaft (22), and the spline receiving member (30) engages with the boss (30a) and the spline (30a). The boss comprises a sleeve (30b) integrally provided on the boss and extending rearward, and includes the screw (19) and the screw shaft (2).
2) is connected from the hollow open portion (E) of the sleeve (30b) with a long bolt (29).

[0011]

Based on the above construction, in the injection step, the spline receiving member (3) is operated by the switching means (38, 36).
0, 11) engage the fixing members (1, 39) to prevent rotation of the screw (19) and male screw (25). In this state, the rotation of the rotor (3) of the electric motor (5) is controlled by the sleeve member (9) and the torque control means (40).
When transmitted to the female screw member (15) through the male screw member (15), the male screw (25) rapidly advances due to the screwing / rotation of the female screw member (15), and accordingly, the screw ( 1
9) also advances in the heating cylinder (17) and injects molten resin to fill the mold.

Further, in the plasticizing step, the spline receiving member (30, 1) is operated by the switching means (38, 36).
1) is engaged with the sleeve members (9, 11) to rotate the rotor (3) of the electric motor (5) to rotate the sleeve member (9),
It transmits to a male screw (25) and a screw (19) via a spline receiving member (30) and a spline (26). At the same time, by controlling the torque control means (40),
The transmission torque from the sleeve member (9) to the female screw member (15) is regulated, and the female screw member (15) rotates with a predetermined torque capacity. Therefore, in this state, based on the rotation of the screw (19), the resin is melted and conveyed in the front end direction, and the pressing reaction force by the molten resin is applied to the screw (1
9) and the pressing reaction force exceeds the predetermined torque capacity, the torque control means (40) slips to rotate the female screw member (15) relative to the male screw (25), Withdraw the screw (25) and screw (19). As a result, the screw (19) retreats while rotating, melting the resin and weighing it.

The reference numerals in the parentheses above are for comparison with the drawings, but do not limit the structure of the present invention.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a screw driving device of an electric injection molding machine according to the present invention, and FIG. 2 is a sectional view embodying the same.

The screw drive device U has a cylindrical casing 1, in which a motor core 2 is fixed, and a rotor 3 arranged facing the inner circumference of the core 2. Thus, for example, an electric hollow motor 5 having a predetermined capacity such as a three-phase basket induction motor is constructed. Also,
A sleeve member 9 is rotatably and axially immovably supported by the casing 1 and a lid portion 1a integral with the casing 1 through bearings 6 and 7. The sleeve member 9 is integrally formed with the rotor 3 by a key or the like. It is connected. The sleeve member 9 is composed of two members 9a fixed by bolts 10,
9b and extends to a length shorter than the casing 1, and has a spline-like engaging claw 11 formed on the inner diameter portion of the base end portion thereof, and bearings 12, 13 on the inner diameter portion of the distal end side. The ball nut member 15 is rotatably supported via.

On the other hand, a heating cylinder case 16 is fixed to the tip of the casing 1, a heating cylinder 17 is fixed in the case 16, and a screw 19 is rotatably supported in the cylinder 17. .. A material supply hole 20 extending to the screw 19 is formed in the case 16 and the cylinder 17, and a hopper 21 is provided so as to communicate with the supply hole 20 (see FIG. 1). A screw shaft 22 is coaxially fixed to the tip of the screw 19. A ball screw 25 is formed on the screw side of the screw shaft 22, a spline 26 is formed on the opposite side, and a through hole 27 is formed in the center of the screw shaft 22, and the through hole 27 has a base end side. A long bolt 29 is inserted into the screw 19 and screwed into a screw hole 19a formed in the screw 19 to be fixed.

A cylindrical spline boss 30a is slidably fitted into the spline 26 of the screw shaft 22, and a sleeve 30b is integrally connected to the boss 30a. Constitutes the spline receiving member 30. Further, an annular piston member 33 is rotatably and axially moved integrally with the end of the sleeve 30b via a bearing 32.
Is connected to the casing 1. The cap member 1b integral with the casing 1 has an annular cylinder portion 35 (and an end portion 35).
a) is fixed by a bolt, and the piston member 33 and the cylinder portion 35 constitute an air or hydraulic actuator 36. On the other hand, a spline-like engaging claw 37 is formed on the outer peripheral surface at one end of the sleeve 30b, and a spline-like engaging claw 39 is also formed on the inner peripheral surface of the cap member 1b which is a fixing member. The claw 37 of the sleeve 31 engages with either the fixed claw 37 or the rotary claw 11 based on the movement based on the actuator 36, thereby forming a switching dock clutch 38.

On the other hand, the ball nut member 15 is screwed into the ball screw 25 of the screw shaft 22 via balls, and these balls can circulate in the nut member 15. The nut member 15 has an end plate 15a.
At the same time, the extension member 15b is integrally fixed. Then, between the nut extension member 15b and the rotor sleeve member 9b, as shown in FIG. 2, an electromagnetic powder clutch 40 and an electromagnetic clutch 41 are arranged side by side in the axial direction. In the clutch 41, both exciting coil portions 40a and 41a are fixed to the casing 1 by positioning pins 42 and 43, respectively. The powder clutch 40 has an outer cage 40b fixed to the inner peripheral surface of the sleeve member 9b, an inner cage 40c fixed to the outer peripheral surface of the nut extension 15b, and an electromagnetic powder 40d sealed between these cages. Therefore, the amount of torque transmitted between the sleeve member 9b and the nut extension portion 15b can be adjusted as appropriate by the value of the current supplied to the exciting coil portion 40a. Therefore, the torque from the rotor sleeve member 9 to the nut member 15 can be controlled. It constitutes a torque limiter that transmits while controlling the amount to a fixed amount.

On the other hand, the electromagnetic clutch 41 assists the electromagnetic powder clutch 40, and the nut extension 1
It has a movable plate 41b supported by a ring plane 15c fixed at the end of 5b so as to be slidable only in the axial direction, and a suction rising portion 41c formed at the end of the sleeve member 9b. By exciting 41a, the movable plate 41b is attracted to the rising portion 41c, and the torque of the sleeve member 9 is transmitted to the nut member 15. When the capacity of the injection molding machine is small, the electromagnetic clutch 41 is
As shown in FIG. 1, it may be omitted. In this case, at the time of injection, an overcurrent is supplied to the coil 40a of the electromagnetic powder clutch 40 to integrally connect the sleeve member 9 and the nut member 15.

Further, the end cap member 1 of the casing
A first rotary encoder 45 is provided at b, and the encoder 45 is connected to the sleeve member 9 via gears 46 and 47. Also, the end cap member 1
A second rotary encoder 49 is arranged at b, and a gear 50 fixed to the input shaft of the encoder 49 is meshed with spline teeth 37 forming the engaging claw formed on the spline sleeve 30b. There is. Further, the heating cylinder case 16 is provided with a third rotary encoder 51, and a gear 52 fixed to the input shaft of the encoder meshes with a gear 53 fixed to the ring plate 15c. Therefore, the first encoder 45 can detect the rotation amount of the sleeve member 9 that is integral with the rotor 3 of the electric motor 5, and the second encoder 49 can detect the rotation amount of the spline receiving member 30 and thus the screw 19 that rotates integrally therewith. The third encoder 51 can detect the rotation amount of the nut member 15. The position of the screw 19 can be detected by the difference between the second encoder 49 and the third encoder 51, and the slip amount of the electromagnetic powder clutch 40 during the back pressure control is the same as that of the first encoder 45 and the third encoder 51. It can be detected by the difference from the encoder 51 of No. 3.

The first encoder 45 can be omitted by using a synchro clutch in which the switching clutch 38 can be switched at any position, and as shown in FIG. 1, the heating cylinder case in the casing 1 can be omitted. A strain gauge 55 is attached to a predetermined position from the fixed portion of 16, and the transmission torque by the powder clutch 40, that is, the back pressure pressure and the injection pressure acting on the screw 19 at the time of back pressure control are directly detected, and the closed loop method is adopted. It is also possible to control by.

Next, the operation of this embodiment will be described.

In the injection process, the actuator 36
Air (or hydraulic pressure) is supplied to the passage A of the piston member 3
3 is moved to the left in the figure. Then, in the switching dock clutch 38, the spline claw 37 engages with the fixed claw 39, the rotation of the spline receiving member 30 is blocked, and therefore, the screw shaft 22 and the screw engaged with the boss 30 a at the spline 26. The rotation of 19 is also blocked.
On the other hand, an overcurrent is supplied to the coil of the electromagnetic powder clutch 40, and the nut member 15 is integrally connected to the rotor sleeve member 9 by the powder 40d. In the case where the electromagnetic clutch 41 is provided, a current is supplied to the coil 41a, the movable plate 41b is attracted to the rising portion 41c, the nut member 15 is connected to the sleeve member 9, and the torque transmitted by the powder clutch 40 is transmitted. Supplement the shortfall of.

Then, the rotation of the rotor 3 of the electric hollow motor 5 is transmitted to the sleeve member 9 and further to the nut member 15 via the electromagnetic powder clutch 40 (and the electromagnetic clutch 41), and in this state. Since the ball screw 25 of the screw shaft 22 is prevented from rotating, the screw shaft 22 and the screw 19 rapidly move in the direction of arrow D based on the rotation of the nut member 15 in the direction of arrow C. As a result, a predetermined amount of resin melted by the rotation of the screw is injected from the nozzle and filled in the mold.

At this time, the injection speed of the screw 19 can be controlled by looking at the detection value of the first or third rotary encoder 45 or 51 and controlling the rotation speed of the nut member 15.

Next, a plasticizing step of melting and measuring a predetermined amount of resin is started. First, the valve (not shown) is switched to switch the air from the passage A to the passage B. Then, the actuator 36 moves the spline sleeve 30b to the left in the drawing, and the engagement claw 37 of the sleeve 30b is engaged with the engagement claw 11 of the rotor sleeve member 9. At the same time, the coil 41a of the electromagnetic clutch 41 is de-energized to disconnect the coil 41a and the coil 4a of the electromagnetic powder clutch 40.
The control voltage applied to 0a is reduced to a predetermined value, and the torque transmitted by the powder clutch 40 is limited to a predetermined amount.

Then, the rotation of the rotor 3 of the electric motor 5 is transmitted to the spline receiving member 30 through the engagement of the sleeve member 9 and the engaging claws 11 and 37, and further through the spline 26, the ball screw 25 and the screw 19. At the same time, the rotation of the sleeve member 9 is transmitted to the nut member 15 with the transmission torque being limited by a predetermined torque capacity by the torque limiter function based on the electromagnetic powder clutch 40. In this state, based on the rotation of the screw 19, the plastic material supplied from the hopper 21 (FIG. 1) is kneaded and sent in the distal direction, and the plastic material is heated by frictional heat and heating accompanying the kneading action. Cylinder 17
It is melted by the heating of the heater.

The molten resin is stored in the tip of the screw 19, and the screw 19 exerts a return pressing force in the direction opposite to the arrow D by the pressure from the resin. The return pressing force (back pressure) acting on the screw 19 acts as rotation resistance on the nut member 15 rotating together with the ball screw 25, and the rotation resistance based on the back pressure exceeds the transmission torque capacity of the electromagnetic powder clutch 40. Further, the clutch 40 slips, and relative rotation occurs between the nut member 15 and the ball screw member 25. As a result, the screw 19 is rotated at a predetermined number of revolutions and retracts so that the resin pressure does not become higher than a predetermined value.

The position of the screw 19 is detected based on the difference between the second rotary encoder 49 and the third rotary encoder 51, that is, the relative rotation amount between the ball screw 25 and the nut member 15, and the molten resin is measured. To do. At this time, since the back pressure acting on the screw 19 is regulated by the torque limiter function of the electromagnetic powder clutch 40 so as not to exceed a predetermined value, the resin pressure becomes a constant pressure at which a peak does not occur during the back pressure control. Retained. Further, the strain cage 55 or the Kistler sensor (not shown) may directly detect the back pressure acting on the screw 19 to directly control the control voltage of the electromagnetic powder clutch 40. Further, even if the performance of the electromagnetic powder clutch 40 deteriorates due to aging, it can be easily dealt with by current correction by the NC control device.

Then, the screw 19 is rotated and retracted, the resin is melted and measured to a predetermined amount, and then the resin is injected in the injection step described above.

When replacing the screw 19, as shown in FIG. 2, the long bolt 29 is rotated from the hollow open portion E of the sleeve 31 and the annular piston member 33, and the tip of the bolt is screwed into the screw hole of the screw. It is easily performed by removing from 19a.

It has already been stated that the electromagnetic clutch 41 is not required when the injection molding machine has a sufficient torque capacity for the electromagnetic powder clutch 40, but the electromagnetic powder clutch 40 also controls the transmission torque of the hysteresis clutch and the like. Of course, it may be replaced with other possible means. Further, the actuator 36 is not limited to pneumatic pressure or hydraulic pressure,
Of course, a solenoid may be used, and the electromagnetic clutch 41 may be replaced with a hydraulic clutch controlled by a valve. Further, the ball screw 25 and the nut member 15
Is not limited to one that interposes a hole, but may be another screw device such as a static pressure screw device.

[0034]

As described above, according to the present invention,
Since one electric motor that operates both during injection and during plasticization is sufficient, it is not necessary to arrange two electric motors side by side in the axial direction, and the axial dimension can be made compact by that amount, and the cost can be reduced. Can be planned.

Further, by controlling one electric motor in a rotating state and switching the switching means and controlling the torque control means, both the injection control and the plasticization control can be performed, and the control becomes simple. In particular, at the time of plasticizing, the torque control means cuts the screw back pressure so that it does not exceed a predetermined value, so that it is possible to prevent peak pressure from occurring.
The pressure can be flattened.

Further, when an electromagnetic powder clutch is used as the torque control means, the torque transmission capacity from the sleeve member to the female screw member can be controlled easily and accurately, and the electromagnetic powder clutch deteriorates due to long-term use. However, the current value can be easily corrected, and the reliability can be improved.

When the rear side of the spline receiving member is opened, the long bolt can be operated from the opening to very easily connect and disconnect the screw and the screw shaft, and the screw can be easily replaced. be able to.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an electric injection molding machine according to the present invention.

FIG. 2 is a sectional view showing a specific example of an electric injection molding machine according to the present invention.

[Explanation of symbols]

 1 casing (fixing member) 3 rotor 5 electric motor (hollow motor) 9 sleeve member 15 female screw member (nut member) 19 screw 22 screw shaft 25 male screw (ball screw) 29 long bolt 30 spline receiving member 30a boss 30b sleeve 36 switching Means (actuator) 38 Switching means (switching claw dock clutch) 40 Torque control means (electromagnetic powder clutch) E Hollow opening U Drive device

Claims (3)

[Claims] 1. An injection molding machine having a driving device for supporting a screw in a heating cylinder, retreating while rotating the screw, and stopping the rotation and advancing the screw, an electric motor arranged in a cylindrical casing. A sleeve member that rotates integrally with the rotor of the electric motor; a spline receiving member that engages with a spline that is connected to the screw; and a female screw that is screwed into a male screw that is connected to the screw. Member, switching means for selectively engaging the spline receiving member with the fixing member such as the casing or the sleeve member, and torque control means for controlling the torque transmitted from the sleeve member to the female screw member. And rotating the sleeve member with the female member in a state in which the spline receiving portion is engaged with the fixing member based on the switching means. The screw to move the screw forward and to restrict the torque transmitted from the sleeve member to the female screw member based on the torque control means while the spline receiving member is engaged with the sleeve member. As a result, the electric injection molding machine is characterized in that the screw is retracted while rotating the screw. 2. The electric injection molding machine according to claim 1, wherein the torque control means is an electromagnetic powder clutch. 3. The spline and the male screw are formed on a single screw shaft, and the spline receiving member is composed of a boss engaging with the spline and a sleeve provided integrally with the boss and extending rearward, The electric injection molding machine according to claim 1, wherein the screw and the screw shaft are connected from a hollow opening portion of the sleeve with a long bolt.