JP2000190362A - Electric injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the breakage of a pressure plate or the like due to a moment load to a screw shaft or the like by arranging an injection motor for transmitting rotation within a heating cylinder to advance/retreat freely a screw shaft, and a transmission shaft for converting rotational movement to linear movement and having a limited advance/retraction amount in the axial direction on the same shaft. SOLUTION: A gear 23 meshed with an annular gear 25 via an intermediate gear 24 is secured to the output shaft 8a of a measuring motor 8, and the annular gear 25 is secured to the outer circumference of the intermediate shaft 18. A hollow 38 is formed of a hollow shaft 18, a bearing holder 17, a pressure plate 1 and bracket 13, and a motor flange 14. The injection motor 9 is provided with a rotor of a hollow rotor shaft 26 fitted and secured therein, and an annular retraction limitation stopper 32 forming an advance/retraction quantity limitation device is provided at the front part of a spline shaft 31, and an extendible quantity limitation device 33 is provided at the rear part thereof. Thus a distance from the spline axial core to the stopper is made short a moment load is prevented from generating on the screw shaft and ball screw shaft, and the breakage of relative members can be prevented.

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. In particular, the present invention relates to a stopper for restricting a retreat limit and a forward limit of a transmission shaft driven by rotation of an injection motor in an injection molding machine.

[0002]

2. Description of the Related Art In an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure, filled into a cavity space in a mold apparatus, and cooled and solidified in the cavity space to form a molded product. You can get it.

Such an injection molding machine has a mold clamping device and an injection device. The mold clamping device has a fixed platen and a movable platen. The mold closing cylinder advances and retreats the movable platen to close, close, and clamp the mold. The mold can be opened.

On the other hand, the injection device is provided with a heating cylinder for heating and melting the resin supplied from the hopper and an injection nozzle for injecting the molten resin, and a screw is rotatable in the heating cylinder and movable back and forth. It is arranged in. Then, the screw is moved forward, the resin is injected from the injection nozzle, and the screw is moved backward to measure the resin.

[0005] By the way, the applicant of the present invention
An invention filed on Japanese Patent Application No. 9-308662 (hereinafter referred to as "prior invention") will be described below with reference to FIG. In FIG. 7, reference numeral 150 denotes a heating cylinder, and a screw 151 is disposed in the heating cylinder 150 so as to be able to advance and retreat and to be rotatable as in the conventional cylinder. And the screw 151
It has a screw head at the front end, extends backward in the heating cylinder 150, and has a bearing box 1 at the rear end.
53 is fixed. Further, a spiral flight 154 is formed around the screw 151, and the flight 15
A groove is formed between the four.

A hopper is fixed to the heating cylinder 150 (not shown). The resin supply port from the hopper is formed at a position corresponding to the rear end of the screw groove when the screw 151 is placed at the forefront in the heating cylinder 150. Therefore, when the screw 151 is rotated during the measuring process, the resin in the form of pellets is supplied from the inside of the hopper, and the resin enters the heating cylinder 150 and is advanced in the groove of the screw.

[0007] A heater (not shown) is provided around the heating cylinder 150, and the heating cylinder 150 is heated by the heater to melt the resin in the screw groove.
Therefore, when the screw 151 is rotated, the screw 151 retreats due to the resin pressure, and one shot of the melted resin accumulates in front of the screw head.

Next, during the injection step, the screw 151
When the is advanced without rotating, the resin accumulated in front of the screw head is injected from the injection nozzle 152 and is filled in the cavity space of the mold. A driving unit 155 for rotating or moving the screw 151 forward or backward is provided behind the heating cylinder 150. Drive unit 1
55 includes a metering motor 157 movably disposed with respect to the frame 156 and an injection motor 158 fixed to the frame 156. The injection motor 158 and the screw 151 are disposed on the same axis. I have.

A guide bar 159 extending parallel to the screw 151 is provided on the frame 156.
The weighing motor 157 moves along 9. For this purpose, a support plate 160 is slidably disposed with respect to the guide bar 159, and a weighing motor 157 is attached to the support plate 160. A driving pulley 161 is fixed to the output shaft of the weighing motor 157, and a driven pulley 163 is fixed to the outer periphery of the box body 162 of the bearing box 153. The driving pulley 161 and the conventional pulley 163 are fixed.
A timing belt 164 is stretched between them. The drive box pulley 161, the driven pulley 163, and the timing belt 164 form the bearing box 15
Transmission means for connecting the motor 3 and the weighing motor 157 is configured.

On the other hand, the injection motor 158
The rotor 166 is rotatably supported by a frame 156. The stator 165 is fixed to the stator 165 and the rotor 166 is disposed on the inner peripheral side of the stator 165. For this purpose, a hollow rotor shaft 167 is fitted into and fixed to the rotor 166, and both ends of the rotor shaft 167 are supported by bearings 168 and 169 in the frame 156.
It is supported by.

Further, bearings 170 and 171 are provided in the bearing box 153, and the screw 151 and the ball screw shaft 172 as a transmission shaft are connected to each other by these bearings so as to be relatively rotatable.
Nut 173 fixed to the vehicle via a load cell 177
And a screw portion 174 formed on the ball screw shaft 172 are screwed together. The rotational movement is converted to a linear movement by the screw portion 174 of the ball screw shaft.

Therefore, in the measuring step, when the measuring motor 157 is driven, the rotation of the measuring motor 157 is sequentially transmitted to the driving pulley 161, the timing belt 164, the box body 162 and the screw 151, and the screw 151 rotates. The resin moves to the front of the screw head. In this case, since the screw 151 and the ball screw shaft 172 are relatively rotatably connected via the bearing box 153, the rotation transmitted to the box main body 162 is not transmitted to the ball screw shaft 172, but the heating cylinder 150 The pressure of the resin inside is transmitted to the ball screw shaft 172 via the bearing box 153. Therefore, the ball screw shaft 172 moves backward while rotating, and accordingly, the screw 151 moves backward. When the screw 151 is retracted, a back pressure is applied to the screw 151 against the pressure of the resin.

On the other hand, in the injection motor 158, by supplying a current of a predetermined frequency to the stator 165, the screw 151 can be advanced without rotating. Therefore, the hollow rotor shaft 16
7, an annular locking member 175 is fixed, and a spline 176 formed on the inner circumference of the locking member 175 and a spline formed on the outer circumference of the rear part of the ball screw shaft 172 are engaged. The spline 176 forms a rotation transmitting unit that transmits the rotation of the injection motor 158.

Therefore, in the injection process, when the injection motor 158 is driven, the rotation of the injection motor rotates the rotor shaft 167, the locking member 175 and the ball screw shaft 17.
2 sequentially. Since the ball nut 173 is fixed to the frame 156, the ball screw shaft 17
2 rotates and advances, and advances the screw 151. At this time, the radiation output applied to the timing belt 164 is transmitted to the load meter 177 via the bearing box 153 and detected. The ball screw shaft 172 moves forward and backward by a stroke S in the axial direction.
(FIG. 7).

As described above, the rotation of the injection motor 158 is performed without the intervention of the speed reduction mechanism, the pulley, or the like.
2, the mechanical efficiency can be increased and the inertia can be reduced. However, in the electric injection molding machine, the injection is performed by driving the motor to advance the screw, but it is necessary to prevent the tip of the screw from colliding with the tip of the heating cylinder even if the screw is advanced too much by mistake. .

As a means for solving this problem, for example, as shown in FIG. 8, a ring-shaped stopper 181 is provided on a pressure plate 178 for advancing a screw, and a valve nut 184 is provided on a front plate 180 to which a heating cylinder 179 is fixed. There is a configuration in which the screw 183 is prevented from moving forward over a certain stroke.

With such a configuration, even if the pressure plate 178 attempts to move until the screw collides with the heating cylinder due to a malfunction of the controller or the like, the pressure plate 178 and the screw are moved by the stopper 18.
1 is prevented from being advanced by a valve nut 184 fixed to the front plate 180, and the screw is stopped before the cylinder collides with the cylinder, which is safe.

However, when such a stopper is provided, since the ring-shaped stopper 181 is provided at a position distant from the axis of the screw 183, even if the pressure plate 178 is slightly inclined, the stopper 181 and the valve nut As a result, the pressure plate 178 and the ball screw 182 were subjected to excessive stress. Further, the pressure plate 178 is inclined even by a slight dimensional difference between the stopper 181 and the valve nut. As a result, a moment load is applied to the screw shaft or the ball screw shaft, causing mechanical damage.

[0019]

In the above-described electric injection molding machine, a moment is applied to the screw shaft or the ball screw shaft when the electric injection motor interferes with the stroke limit, and the pressure caused by the moment load is increased. The purpose is to prevent damage to plates and the like.

[0020]

SUMMARY OF THE INVENTION A heating cylinder, a screw disposed in the heating cylinder so as to be movable forward and backward, an injection motor for moving a screw shaft forward and backward, and a rotatable relative to the screw in the heating cylinder. And a transmission shaft having a rotation transmitting unit for transmitting the rotation of the injection motor and a movement direction conversion unit for converting the rotational movement into a linear movement, wherein the injection motor and the transmission shaft are on the same axis. The transmission shaft is disposed inside the rotor constituting the injection motor, and moves back and forth in the axial direction, and a movement limit means for limiting the movement in the axial direction is provided on the transmission shaft. In the above configuration, the transmission shaft includes a ball screw portion and a spline portion, and the movement amount limiting means includes a forward limit stopper provided at a rear end of the spline portion and a retreat limit stopper provided at a front portion of the spline portion. The front end of the nut and the step of the spline nut are configured to be in contact with each other.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given with reference to FIGS. The basic technical idea that the present invention is an electric injection molding machine is an extension of the electric injection molding machine according to the prior invention described with reference to FIG. However, the present invention relates to a stopper which further improves this and restricts a retreat limit and a forward limit of a transmission shaft driven by rotation of an injection motor in an injection molding machine.

FIG. 1 is a cross-sectional view of an injection molding machine according to the present invention, and FIG. 2 is an external side view of the injection molding machine according to the present invention. FIG. 3 is a sectional view taken along the arrow A in FIG. 4 is a sectional view taken along the arrow C of FIG. 1, FIG. 5 is a sectional view taken along the arrow D of FIG. 1, and FIG. 6 is a sectional view taken along the arrow E of FIG. 1 and 2, 1
Denotes a heating cylinder.
Similar to the prior art described below, a screw (see FIG. 7) is provided so as to be able to advance and retreat and rotate freely.
The screw and the screw shaft 3 extend rearward in the heating cylinder 1, and the rear end of the screw shaft 3 is fixed to a screw support plate 4 (see FIG. 6).

A resin supply port 5 is formed at a set location in the heating cylinder 1 as in the case of FIG. 7 and the following figures, and a hopper (FIG. 2) is fixed on the resin supply port 5. The resin supply port 5 is formed at a position corresponding to the last end of a groove formed by flight of the screw when the screw is placed at the forefront in the heating cylinder 1. Therefore, when the screw shaft 3 is retracted while rotating during the measuring step, pellet-shaped resin is supplied from the resin supply port 5.

A heater (not shown) is provided around the heating cylinder 1, thereby heating the heating cylinder 1 and melting the resin in the groove of the screw 2. Therefore, when the screw 2 is rotated, the screw 2 retreats due to the resin pressure, and one shot of molten resin accumulates in front of the screw head.

Next, when the screw shaft 3 is advanced without rotating during the injection step, the molten resin accumulated in front of the screw head is injected from the injection nozzle and filled in the cavity space in the mold. .

By the way, behind the heating cylinder 1, there is a drive unit 6 for rotating and moving the screw 2 forward and backward. The drive unit 6 includes a weighing motor 8 movably disposed with respect to the machine frame 7 and an injection motor 9 fixed to the machine frame 7, and the injection motor 9 and the screw shaft 3 are coaxial. It is arranged on the line.

A plurality of guide rods 10 extending in parallel with the screw 2 are provided on the machine frame 7 (FIG. 4), and the pressure plate 11 supporting the measuring motor 8 moves along the guide rods 10. . As shown in FIGS. 1 and 2, the machine frame 7 includes a front frame 7 a that covers the heating cylinder 1 and a ball nut 3 that will be described later.
6 and a rear frame 7b supporting the guide rod 10. The front and rear frames 7a and 7b are
As shown in the figure, the two connecting rods 12 are integrally connected.

A motor mounting bracket 13 (FIGS. 1 and 3) is mounted on the side of the pressure plate 11, and the measuring motor 8 is mounted on the bracket 13 via a motor flange 14. A bearing box 16 is rotatably mounted in the pressure plate 11 via bearings 15a and 15b. 17
Is a bearing holder, which holds one bearing 15b. The bearing box 16 includes an annular hollow shaft 18 fixed to the rear of the screw support plate 4 and a bearing retainer 19. The front end of the ball screw shaft 30 is rotatably supported via bearings 20 and 21. Numeral 22 denotes a bearing holder, which allows the bearing 20 to hold the bearing holder 1
9 is held.

The output shaft 8a of the measuring motor 8 in FIG.
Gear 23 is fixed to the intermediate gear 24.
Through the ring gear 25. Ring gear 25
Is fixed to the outer periphery of the hollow shaft 18, and one end of the hollow shaft 18 is bolted to the rear end of the screw support plate 4. Reference numeral 38 denotes a hollow portion, which includes a hollow shaft 18, a bearing holder 17, a pressure plate 11, and a bracket 1.
3, formed with the motor flange 14, and the gears 23, 24, 25 are housed in the cavity.

The injection motor 9 has a stator and a rotor. A hollow rotor shaft 26 is fitted and fixed to the rotor. Both ends of the hollow rotor shaft 26 are bearings 27,
At 28, a spline nut 29 is rotatably supported within the motor frame, and a spline nut 29 is fixed within the hollow rotor shaft 26.
A spline shaft 31 fixed to the rear end of the ball screw shaft 30 is slidably engaged with the spline nut 29.
Reference numeral 32 denotes an annular retreat limit stopper provided at a front part of the spline shaft 31 and constituting an advance / retreat amount limiting device, and reference numeral 33 denotes a forward limit stopper provided at a rear end of the spline shaft 31. Since the front and rear stoppers 32 and 33 are provided, it is possible to prevent the spline shaft 31 from coming into contact with these stoppers in the front and rear stroke limits and to prevent further stroke. The forward end stopper 33 is provided with the spline nut 2.
9 and is stopped by engaging with the stepped portion 29a provided on the base member 9.

Reference numeral 34 denotes a guide rod supporting member for supporting the rear end of the guide rod 10, to which the injection motor 9 is fixed. 35 is a rear frame 7b and a ball nut 3
6, a load cell fixed to a flange 36a provided at the rear end, and an oil supply plate 37 having an oil supply port is fixed to an upper portion of the load cell 35. Eventually, the guide rod 10 penetrates the rear frame 7b, and is supported by the guide rod support member 34 by being tightened with the screw 10a.

With the above configuration, in the measuring step,
When the weighing motor 8 is driven, its rotation is transmitted from the output shaft 8a to the gears 23, 24, and 25, and the rotation of the ring gear 25 rotates the bearing box 16. The bearing box 16 is composed of the bearings 20 and 21 and the ball screw shaft 3.
This rotation is transmitted to the screw shaft 3 via the screw support plate 4 because it is freely rotatable with respect to 0.

In the injection step, the hollow rotor shaft 26 is rotated by the rotation of the injection motor 9, and the spline shaft 3 is rotated.
Then, the ball screw shaft 30 integrally fixed to the front end of the spline shaft 31 is rotated. Then, the ball screw shaft 30 is advanced by the ball nut 36, and the screw shaft 3 is advanced to perform injection. At this time, the backward limit stopper 32 contacts the front end of the spline nut 29 to limit the backward stroke, and the forward limit stopper 33 contacts the step 29a of the spline nut 29 to limit the forward stroke.

[0034]

(1) Since the advance / retreat control device is provided coaxially with the transmission shaft in this way, the distance of the advance / retreat control device from the axis of the transmission shaft is shortened. Therefore, the generation of the moment load can be minimized, and the damage of the related members can be prevented. (2) Since a spline nut is provided inside the rotor of the injection motor and the stepped portion 29a is provided with a stopper for forward movement and a stopper for backward movement at the rear end of the ball screw shaft, the distance from the spline shaft center to the stopper is provided. And the moment load is prevented from being generated on the screw shaft or the ball screw shaft at the time of the stroke limit interference. (3) The structure is extremely simple because the advancing / retreating means has a contact structure between the stopper provided at the front and rear ends of the spline shaft and the front and rear ends of the spline nut.
This is a major contributor to compact molding machines.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an injection molding machine embodying the present invention.

FIG. 2 is an external side view of the same.

FIG. 3 is an A sectional view of FIG. 1;

FIG. 4 is a sectional view taken along the line C in FIG. 1;

FIG. 5 is a sectional view taken along the line D in FIG. 1;

FIG. 6 is a sectional view taken along the line E in FIG. 1;

FIG. 7 is a “prior invention” by the present applicant with an electric injection molding machine.
Is shown.

FIG. 8 shows a known molding machine provided with a stopper for restricting advance and retreat.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating cylinder 2 Screw 3 Screw shaft 4 Screw support plate 5 Resin supply port 6 Drive unit 7 Machine frame 7a Front frame 7b Rear frame 8 Metering motor 9 Injection motor 10 Guide rod 11 Pressure plate 12 Connecting rod 13 Motor mounting Bracket 14 Motor flange 15a, 15b Bearing 16 Bearing box 17 Bearing holder 18 Hollow shaft 19 Bearing retainer 20 Bearing 21 Bearing 22 Bearing retainer 23 Gear 24 Intermediate gear 25 Annular gear 26 Rotor shaft 27 Bearing 28 Bearing 29 Spline nut 29a Step 30 Ball Screw shaft 31 Spline shaft 32 Backward limit stopper 33 Forward limit stopper 34 Guide rod support member 35 Load cell 36 Ball nut 37 Oil plate 38 Cavity

Claims (2)

[Claims] 1. A heating cylinder, a screw disposed in the heating cylinder so as to be able to move forward and backward, an injection motor for moving a screw shaft in and out, and a rotatably connected relative to a screw in the heating cylinder, A transmission shaft for transmitting the rotation of the injection motor and a transmission shaft having a movement direction conversion unit for converting the rotational movement into a linear movement, wherein the injection motor and the transmission shaft are arranged on the same axis, An electric injection molding machine, wherein the transmission shaft is located inside a rotor constituting an injection motor, and moves forward and backward in the axial direction, and an advance / retreat amount limiting means for limiting the axial movement is provided on the transmission shaft. . 2. The power transmission shaft comprises a ball screw portion and a spline portion, and the movement amount limiting means includes a forward limit stopper provided at a rear end of the spline portion and a retreat limit stopper provided at a front portion of the spline portion. 2. The electric injection molding machine according to claim 1, wherein the front end of the nut and the step portion of the spline nut are configured to abut.