JP3353055B2 - 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, it relates to the configuration of an injection frame of 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] An injection device of an electric injection molding machine using an electric motor for moving the screw forward and backward has been provided. Hereinafter, two prior arts will be described with reference to FIGS. (Prior Art 1) FIG. 7 is a schematic view of an injection device of a conventional electric injection molding machine. 7, reference numeral 101 denotes an injection device, and reference numeral 102 denotes an injection device frame. A heating cylinder 104 is fixed in front of the injection device frame 102, and an injection nozzle 103 is provided at a front end of the heating cylinder 104. The heating cylinder 104 has a hopper 105
Are arranged. A screw 106 is disposed in the heating cylinder 104 so as to be able to advance and retreat and to be rotatable, and a rear end of the screw 106 is rotatably supported by a support member 107.

A weighing motor 108 having a speed reduction mechanism is attached to the support member 107.
Rotation of the screw 1 via the timing belt 109
06. A screw shaft 111 is rotatably supported in parallel with the screw 106, and the screw shaft 1
An injection motor 113 with a speed reduction mechanism is connected to the rear end of the motor 11 via a timing belt 112 so that the screw shaft 111 can be rotated by the injection motor 113. A nut 114 fixed to the support member 107 is screwed to the front end of the screw shaft 111.
Therefore, by driving the injection motor 113 and rotating the screw shaft 111 via the timing belt 112, the nut 114 can be moved in the axial direction.

In the injection device 101 having the above-described configuration, when the measuring motor 108 is driven and the screw 106 is rotated via the timing belt 109 during the measuring process,
Resin is supplied from the hopper 105 and the heating cylinder 104
Inside, the resin is heated and melted. The screw 1
With the rotation of 06, the resin accumulates in front of the screw 106, and the screw 106 moves backward (moves rightward in the figure).

In the injection step, the injection motor 11
3 and the screw shaft 1 via the timing belt 112.
11 is rotated. At this time, the nut 114 and the support member 107 move with the rotation of the screw shaft 111 and advance the screw 106, so that the resin accumulated in front of the screw 106 is injected from the injection nozzle 103 toward the cavity.

Next, the invention filed by the present applicant as a Japanese Patent Application No. 9-308662 on November 11, 1997 (hereinafter referred to as "the prior invention") will be described with reference to FIG. . In FIG. 8, reference numeral 150 denotes a heating cylinder.
The point 1 is provided so as to be able to advance and retreat and to be rotatable as in the conventional one. The screw 151 has a screw head at the front end and the heating cylinder 1
50 extends rearward, and a bearing box 153 is provided at the rear end.
Has been fixed. 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.

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 in parallel with 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 a ball screw shaft 172 as a transmission shaft are relatively rotatably connected by these bearings.
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 step, 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. 8).

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.

Now, the above "prior invention" has solved many of the problems in the prior art of electric injection molding machines. However, in an electric injection molding machine, it is necessary to accurately measure a substantial resin reaction force. As a means for solving this problem, as shown in FIG. 9, a ball screw 178 is attached to a pressure plate 182 so as to be rotatable and immovable in the axial direction, and the ball screw 178 is fixed to a rear plate 179 via a load cell 180. The ball nut 181 is screwed. By rotating 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. And ball screw 178
Is not transmitted to the pressure plate 182, so that it is not related to the fluctuation of the rotation force, and the sliding resistance of the pressure plate 182 against 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.

[0022]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel structure of an injection frame of a molding machine capable of reducing the sliding resistance of a pressure plate and improving the screw position detection accuracy. With the goal.

[0023]

Means for Solving the Problems (1) A heating cylinder,
A screw disposed in the heating cylinder so as to be able to move forward and backward, an injection frame for fixing the heating cylinder, a ball nut fixed to the injection frame, and screwed with the ball nut to rotate relative to the screw A ball screw shaft rotatably supported, and a pressure plate that is advanced and retracted by the ball screw shaft and rotatably supports the screw. The pressure plate is separate from the constituent members of the injection frame. It was supported by a guide rod so that it could move forward and backward. (2) In the above (1), the components of the injection frame are constituted by a front plate on which a heating cylinder is fixed, a rear plate on which a ball nut is fixed, and a connecting rod for integrally connecting the front plate and the rear plate. Configured. (3) In the above (2), a ball nut is fixed to the rear plate via a load cell. (4) In the above (1), the guide rod is installed in parallel with the injection axis, one end of the guide rod is supported by the front plate, and the other end is supported by a guide rod support member disposed at the rear of the rear plate. I did it. (5) In the configuration of (4), a position sensor for measuring a distance between the guide rod support member and the pressure plate is provided.

[0024]

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 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 place in the heating cylinder 1 as in the case shown in FIG. 7 and below, 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 to heat the heating cylinder 1 and melt 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 process, 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 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 the machine frame 7 constituting the injection frame (FIG. 4). A pressure supporting the measuring motor 8 is provided along the guide rods 10. The plate 11 moves. As shown in FIGS. 1 and 2, a machine frame 7 constituting an injection frame includes a front frame 7 a covering a portion of the heating cylinder 1, a ball nut 36 and a guide rod 10 described later.
The front and rear frames 7a and 7b are integrally connected by four connecting rods 12 as shown in FIG.

A bracket 13 (FIGS. 1 and 3) for mounting a weighing motor is mounted on a side portion of the pressure plate 11, and a weighing 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. 1
Reference numeral 7 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.
Then, the ball screw shaft 30 via the bearings 20 and 21
The front end is rotatably supported. 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.

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.
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.
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.

Reference numeral 39 denotes a position sensor attached to the pressure plate 11 via a bracket, and a position sensor 40 attached to the guide rod support member 34 via a bracket. It measures the distance between them. Then, the position of the screw is detected by the position sensors 39 and 40. These position sensors 39, 40
Are a pressure plate 11 supported by a guide rod 10 not subjected to an injection pressure and a guide rod support member 34.
, There is no expansion between the members due to the injection pressure, and the distance between the members can be accurately detected.

Further, since the pressure plate 11 is supported by the guide rod 10 which does not receive the injection pressure, the sliding resistance is reduced, and the detection accuracy of the load cell 35 can be improved.

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 fixed at the front end of the spline shaft 31 is further rotated. Then ball nut 3
6, the ball screw shaft 30 is advanced, and the screw shaft 3
Is advanced to perform injection.

[0039]

(1) The configuration is as described above. That is, the pressure plate is guided by a guide rod which is different from the front plate, the rear plate and the connecting rod which constitute the injection frame, and no injection pressure is applied to the guide rod, so that the rod diameter can be reduced. Therefore, the sliding resistance is reduced, and the detection accuracy of the load cell held on the rear plate and the ball nut can be improved. (2) Since a position sensor for measuring the distance between the guide rod supporting member and the pressure plate, which is not affected by the injection pressure, is provided, highly accurate position measurement is possible.

[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 shows a known molding machine.

FIG. 8 shows a “prior invention” by the present applicant in the same electric injection molding machine.

FIG. 9 shows an example of an injection molding machine provided with a load cell for measuring a resin reaction force.

[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 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 Guide rod support member 35 Load cell 36 Ball nut 37 Lubrication plate 38 Cavity 39 Position sensor 40 Position sensor

Claims (5)

(57) [Claims] 1. A heating cylinder, a screw disposed in the heating cylinder so as to be able to advance and retreat, an injection frame for fixing the heating cylinder, a ball nut fixed to the injection frame,
A ball screw shaft screwed with a ball nut and rotatably supported relative to the screw; a pressure plate that is advanced and retreated by the ball screw shaft and rotatably supports the screw; An injection molding machine, wherein the pressure plate is supported by a guide rod different from the constituent members of the injection frame so as to be able to advance and retreat in the front-rear direction. 2. A component of the injection frame includes a front plate on which a heating cylinder is fixed, a rear plate on which a ball nut is fixed, and a connecting rod for integrally connecting the front plate and the rear plate. The injection molding machine according to claim 1, wherein: 3. The injection molding machine according to claim 2, wherein a ball nut is fixed to the rear plate via a load cell. 4. A guide rod is installed parallel to the injection axis, and one end of the guide rod is supported by a front plate,
The injection molding machine according to claim 1, wherein the other end is supported by a guide rod support member disposed at a rear portion of the rear plate. 5. The injection molding machine according to claim 4, further comprising a position sensor for measuring a distance between the guide rod support member and the pressure plate.