JP3288028B2 - Injection device of electric injection molding machine - Google Patents

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 an injection device of an electric 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] Fig. 7 shows a system disclosed by the present applicant as Japanese Patent Application No. 9-308662 on November 11, 1997 (hereinafter referred to as "Japanese Patent Application No. 9-308662").
(Referred to as "first invention"). In FIG.
Is a heating cylinder, in which a screw 151 is disposed inside the heating cylinder 150 so as to be able to advance and retreat and to be rotatable. The screw 151 has a screw head at the front end, extends rearward in the heating cylinder 150, and has a bearing box 153 fixed at the rear end. A spiral flight 154 is formed around the screw 151, and a groove is formed between the flights 154.

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.

In the electric injection molding machine according to the above-mentioned "prior invention", it is necessary to accurately measure a substantial resin reaction force. As a means for solving this problem, as shown in FIG. 8, a ball screw 178 is attached to the pressure plate 182 so as to be rotatable and immovable in the axial direction, and the ball screw 178 is attached to the rear plate 179.
There is known one that is screwed into a ball nut 181 fixed via a through hole. Rotate the ball screw 178,
The screwing position of the ball screw 178 is changed in the axial direction, and the pressure plate 182 for pressing the injection screw is moved along the guide rod 183. A ball screw 178 is rotatably supported on the pressure plate 182 by a bearing. Since the rotational force of the ball screw 178 is not transmitted to the pressure plate 182, the rotational force is not related to the fluctuation of the rotational force, and the sliding resistance of the pressure plate 182 with respect to the guide rod 183 is always constant. Since the sliding resistance does not fluctuate, the substantial resin reaction force can be accurately measured by the load cell 180 that detects the resultant force of the sliding resistance and the substantial resin reaction force.

However, in such a configuration, the pressure plate 182 slides while being guided by the guide rod 183. However, since the guide rod 183 receives an injection thrust, the guide rod 183 must be enlarged. Therefore, the sliding resistance at the guide rod 183 becomes large. Further, since the guide rod 183 is extended by the injection, the position of the pressure plate 182, that is, the accuracy of detecting the position of the screw is reduced.

As described above, the load cell 180 detects the resultant force of the substantial firing force and the frictional resistance of the guide portion of the pressure plate 182. However, in this structure, (1) Since the injection motor is arranged on the pressure plate 182, the pressure plate 182 receives the reaction force of the rotation torque of the injection motor. (2) There is a problem that the detection of the load cell 180 is adversely affected due to a change in frictional resistance of the guide portion at the time of acceleration / deceleration of the injection motor and at the time of high output.

[0019]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a structure in which a pressure plate of an injection screw is slidably supported by a guide rod. An object of the present invention is to provide an injection mechanism of an electric injection molding machine capable of always maintaining a constant value of a sliding resistance acting on the injection screw and capable of accurately measuring a substantial resin reaction force acting on an injection screw by a load cell. . It is another object of the present invention to improve the detection accuracy of the load cell by preventing the guide portion from being affected by the torque fluctuation of the injection motor, that is, by preventing the friction resistance from fluctuating.

[0020]

Means for Solving the Problems (1) Front plate 7a
A heating cylinder 1 attached to a front plate 7a of a machine frame 7 including a rear plate 7b and a screw 2 rotatably and advancing and retracting in the heating cylinder 1 constitutes the machine frame 7. Rear plate 7b
, A guide rod 10 having one end fixed to the front plate 7a and the other end penetrating the rear plate 7b, and the screw 2 supported slidably by the guide rod 10. And a ball screw shaft 30 rotatably supported by the pressure plate 11, and the ball screw shaft 30 is driven and attached to the other end of the guide rod 10. . (2) In the above (1), the machine frame 7 includes a front plate 7a on which a heating cylinder is fixed, a rear plate 7b on which a ball nut is fixed, and a connecting rod for integrally connecting the front plate and the rear plate. And 12. (3) In the above (1) and (2), the rear plate 7b
, A ball nut 36 is fixed via a load cell 35. (4) In the above (1) and (2), the guide rod 10 for guiding the pressure plate 11 is installed in parallel with the ball screw shaft 30, one end of the guide rod 10 is fixed to the front plate 7a, and The end was fixed to the injection motor 9 via a motor frame support member 34, and was configured with a gap a between the rear frame 7b and the motor frame support member 34.

[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.

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 B in FIG. 1, FIG. 5 is a sectional view taken along the arrow C in FIG. 1, and FIG. 6 is a sectional view taken along the arrow D in 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 place in the heating cylinder 1, and a hopper is provided 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 an injection nozzle and is filled into a cavity space in a mold (not shown). Is done.

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 machine frame 7 constituting an injection frame.
A motor 8 for measurement, which is movably disposed with respect to the motor, and a motor 9 for injection fixed to the machine frame 7. The motor 9 for injection and the screw shaft 3 are arranged on the same axis.

A plurality of guide rods 10 extending in parallel with the screw 2 are disposed on a machine frame 7 constituting an injection frame. A pressure plate 11 supporting a measuring motor 8 moves along the guide rods 10. I do. As shown in FIG. 1, the machine frame 7 constituting the injection frame includes a front frame 7a covering a portion of the heating cylinder 1, and a rear frame 7b supporting a ball nut 36 and a guide rod 10 described later. 7a and 7
b is integrally connected by four connecting rods 12.

A weighing motor mounting bracket 13 is mounted on the side of the pressure plate 11, and the weighing motor 8 is mounted on the bracket 13 via a motor flange 14.
Is installed. A bearing box 16 is rotatably mounted in the pressure plate 11 via bearings 15a and 15b. Reference numeral 17 denotes 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. Reference numeral 22 denotes a bearing holder, which holds the bearing 20 between the bearing holder 19 and the bearing 20.

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. 38 is a hollow shaft 18, bearing holder 1
7, a cavity formed by the pressure plate 11, the bracket 13, and the motor flange 14, in which the gears 23, 24, and 25 are housed.

Next, 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 rotatably supported in the motor frame by bearings 27 and 28,
A spline nut 29 is fixed in the hollow rotor shaft 26, and a spline shaft 31 fixed to the rear end of the ball screw shaft 30 is slidably engaged with the spline nut 29. The forward / backward movement of the spline shaft 31 is restricted by a backward limit stopper 32 and a forward limit stopper 33.

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 constituting an injection frame
And a flange 36a provided at the rear end of the ball nut 36
An oil supply plate 37 having an oil inlet is fixed to the rear of the load cell 35.
After all, the guide rod 10 penetrates the rear frame 7b and is tightly supported by the guide rod support member 34 with the screw 10a.

In FIG. 1, a guide rod support member 34 for mounting the motor frame of the injection motor 9 disposed at the rear of the rear plate 7b is fixed to the front plate 7a via the guide rod 10. That is, the guide rod 10
Is fixed to the guide rod support member 34 for mounting the motor frame of the injection motor 9 disposed at the rear portion thereof through the rear plate 7b with a screw 10a. The guide rod support member 34 is attached to the oil supply plate 37 attached to the rear plate 7b at a further interval a.

[0033]

As described above, the rear frame 7b is integrated with the front plate 7a via the connecting rod 12, but the injection motor 9 is guided by the rear end of the guide rod 10 for guiding the pressure plate 11. Since the guide rod is fixed via the rod support member 34, the guide rod does not receive torque fluctuations of the injection motor 9. Therefore,
The detection accuracy of the load cell 35 can be improved.
Also, the rear frame 7b and the motor frame support member 34
Are separated with an interval a. For this reason, even if a torque fluctuation or the like occurs in the injection motor 9, the guide portion is not affected by the fluctuation, so that the detection accuracy of the load cell 35 is further improved as compared with the related art.

In particular, the magnitude of the sliding resistance acting between the pressure plate 11 and the guide rod 10 is always kept at a constant value, and the substantial resin reaction force acting on the screw 2 is accurately measured by the load cell 35. be able to.

[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 injection molding machine according to the present invention.

FIG. 3 is a cross-sectional view of FIG.

FIG. 4 is a sectional view taken in the direction of the arrow B;

FIG. 5 is a sectional view taken in the direction of arrow C;

FIG. 6 is a sectional view taken along the arrow D in FIG.

FIG. 7 is a sectional view of a prior application filed by the present applicant.

FIG. 8 is a sectional view of a known technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating cylinder 2 Screw 3 Screw shaft 4 Screw support plate 5 Resin supply port 6 Drive section 7 Machine frame 7a Front plate 7b Rear plate 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 Ring gear 26 Rotor shaft 27 Bearing 28 Bearing 29 Spline nut 30 Ball screw shaft 31 Spline shaft 32 Backward limit stopper 33 Forward limit stopper 34 Motor frame support member 35 Load cell 36 Ball nut 37 Lubrication plate 38 Cavity 39 Position sensor 40 Position sensor

Claims (4)

(57) [Claims] 1. A heating cylinder (1) mounted on a front plate (7a) of a machine frame (7) comprising a front plate (7a) and a rear plate (7b); A screw (2) arranged rotatably and advancing and retracting, a ball nut (36) attached to a rear plate (7b) constituting a machine frame (7), and one end to a front plate (7a). A guide rod (10) which is fixed and the other end of which penetrates the rear plate (7b); and a pressure plate (1) which advances and retreats the screw (2) slidably supported by the guide rod (10).
1), and a ball screw shaft (3) screwed with a ball nut (36) and rotatably supported by the pressure plate (11).
0), and an injection motor (9) for driving the ball screw shaft (30) and attached to the other end of the guide rod (10). 2. The machine frame (7) integrally connects the front plate (7a) to which the heating cylinder is fixed, the rear plate (7b) to which the ball nut is fixed, and the front plate and the rear plate. The injection device of an electric injection molding machine according to claim 1, wherein the injection device is constituted by a connecting rod (12). 3. A load cell (3) is attached to the rear plate (7b).
3. The injection device for an electric injection molding machine according to claim 1, wherein a ball nut (36) is fixedly provided via (5). 4. A guide rod (10) for guiding the pressure plate (11) is installed parallel to the ball screw shaft (30), and one end of the guide rod (10) is fixed to the front plate (7a). The other end is fixed to the injection motor (9) via the motor frame support member (34), and is configured with a space (a) between the rear frame (7b) and the motor frame support member (34). The injection device for an electric injection molding machine according to claim 1, wherein: