JPH0780886A - Electrically-driven injection molding machine - Google Patents

Abstract

PURPOSE:To improve a linearly feeding means in an injection molding machine and provide a mold clamping unit whose size is small in a forward and backward direction and an injection unit. CONSTITUTION:In an electrically-driven injection molding machine, each of linearly feeding means 6 for converting a rotational motion into a linear motion is constituted of a ball screw nut mechanism. Two ball screws 9a, 9b having thread parts 11a, 11b whose leads are different butt against each other at their top ends and are joined together. A nut corresponding to each of the thread parts is screwed on the thread parts 11a, 11b, respectively. A moving platen 4 is joined to a stationary platen 3 by a plurality of linearly feeding means, whereby a two-platen type mold clamping unit 1 is formed. The ball screw nut side having a smaller lead is connected to a motor 14 for lockup, and the ball screw nut side having a larger lead is connected to a motor 18 for feeding a mold.

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.

[0002]

2. Description of the Related Art An injection molding machine comprises a mold clamping unit and an injection unit. In an electric injection molding machine, an electric motor drives these units and touches a nozzle.

The mold clamping unit is usually a three-platen type in which a moving platen is arranged between a stationary platen and a rear platen, and the moving platen is guided by a tie bar connecting the stationary platen and the rear platen so that it can be moved back and forth. . The moving platen and the rear platen are connected by a mold clamping mechanism, and in the case of an electric type, the rotation of the mold clamping motor is converted into a linear motion by a ball screw nut mechanism (a linear feed device), which is directly or by a crosshead and a toggle. It is transmitted to the moving platen via a link to open and close the mold.

The same applies to the injection unit, which is usually a three-plate type, in which the moving plate is guided by the tie rods and the ball screw nut mechanism (linear feed device) connected to the rear plate is moved forward and backward by the injection motor. Then, the injection operation is performed. In the nozzle touch device, the nozzle touch motor drives the ball screw nut mechanism (linear feed device) to move the injection unit back and forth with respect to the mold clamping unit.

In these cases, the ball screw in any of the ball screw nut mechanisms is composed of a single screw, and the feed speed of the linear feed device and the pressure (clamping force, injection pressure, touch pressure) given by the feed are The adjustment is performed by adjusting the rotation speed and torque of the motor. Therefore, the feed speed and pressure are limited by the maximum rotation speed and torque of the adopted motor, and cannot be exceeded. Therefore, the motor is selected based on the larger one of the required rotation speed and torque, and in view of the function of the injection molding machine, an unnecessarily large and expensive motor is used.

Such an inconvenience is caused by JP-A-64-2486.
The problem can be solved to some extent by properly using the leads of the ball screw as disclosed in Japanese Patent Laid-Open No. 16 and Japanese Patent Laid-Open No. 63-242618, but the ball screw provided with two different lead screw portions is special and less versatile. Very expensive.

Further, since the 3 platen type clamping unit and the 3 plate type injection unit are 3 platens or 3 plates, the front and rear dimensions are large, and the injection molding machine is difficult to be enlarged as a whole and is processed with high precision. Since a plurality of long tie bars and tie rods (usually four) are used, the injection molding machine is expensive.

[0008]

SUMMARY OF THE INVENTION The present invention is an improvement of a linear feeder in an injection molding machine, and an improved electric feeder provided with a mold clamping unit and an injection unit having small front-rear dimensions. An object is to provide an injection molding machine.

[0009]

[Means for Solving the Problems]

[Invention of Claim 1] An electric injection molding machine provided with a linear feed device for converting rotational motion into linear motion. The linear feeding device is composed of a ball screw nut mechanism, and two ball screws having threaded portions with different leads are joined by abutting their tips. A corresponding nut is screwed into the threaded portion of each ball screw. [Invention of Claim 2] This invention relates to an electric injection molding machine equipped with a two-platen type mold clamping unit.

The moving platen is connected to the stationary platen by a plurality of linear feeding devices each composed of a ball screw nut mechanism.

In each ball screw nut mechanism, two ball screws each having a thread portion with a different lead are joined together by abutting their tips, and a nut corresponding to each thread portion is screwed.

The ball screw nut side with a small lead is connected to the lockup motor, and the ball screw nut side with a large lead is connected to the mold feed motor. [Invention of Claim 3] The present invention relates to an electric injection molding machine including a two-platen injection unit.

The moving plate is connected to the stationary plate by a plurality of linear feeding devices each composed of a ball screw nut mechanism.

In each ball screw nut mechanism, two ball screws each having a threaded portion with a different lead are joined together by abutting their tips, and a nut corresponding to each threaded portion is screwed.

The ball screw nut side with a small lead is connected to the injection pressure motor, and the ball screw nut side with a large lead is connected to the injection feed motor. [Invention of Claim 4] An electric injection molding machine in which an injection unit is connected to a mold clamping unit by a nozzle touch device using a linear feed device composed of a ball screw nut mechanism.

In the ball screw nut device, two ball screws each having a threaded portion having a different lead are joined together by abutting their tips, and nuts corresponding to the respective threaded portions are screwed together.

The ball screw nut side with a small lead is connected to the touch pressure motor, and the ball screw nut side with a large lead is connected to the unit feed motor.

[0018]

The structure in which the ball screw of the ball screw nut mechanism in the linear feed device is formed by abutting and joining two tips provided with threaded portions having different leads reduces the cost of the linear feed device and also requires the required rapid feed.・ Achieve high pressure comfortably. The configuration in which the mold clamping unit and the injection unit are of the two-platen type and the two-plate type reduces the front-back dimension of each unit.

[0019]

【Example】

[Clamping Unit] FIG. 1 shows a two-platen type clamping unit 1 in an injection molding machine. The injection molding machine includes the mold clamping unit 1 and the injection unit 2 of FIG. 2, and their operations are managed by a control device provided in the injection molding machine, as in the conventional case.

In the mold clamping unit 1 (FIG. 1), a stationary platen 3 and a moving platen 4 are erected parallel to each other, and the two platens 3 and 4 are parallel to each other. They are connected by linear feeders 6 and 6 (Fig. 3A). As shown in the figure, the tie bars 5 and 5 and the linear feeding devices 6 and 6 for mold clamping are arranged on diagonal lines of the stationary platen 3 and the moving platen 4, respectively.

The stationary platen 3 is fixed to the base 7, and the moving platen 4 is in the front-rear direction (left and right in the figure).
It is possible to move to. Reference numeral 8 is a mold. The mold clamping linear feeding device 6 is composed of a ball screw mechanism, and two ball screws 9 (a, b) are supported by the coupling member 10 with their tips abutted against each other. The coupling member 10 is fitted into the tie bar 5 and is movable back and forth without interfering with the mold 8 and has a screwing portion 12. The threaded portion 12 has a threaded portion 11 (a, a) of the ball screw 9 (a, b).
b) are screwed together. The screw portion 11a of the ball screw 9a has a small lead, and the screw portion 1 of the ball screw 9b
1b has a large lead. The threaded portion 12 of the coupling member 10 includes female threads corresponding to the threaded portions 11 (a, b), and corresponds to a ball nut.

The ball screw 9a is rotatably supported at a fixed position on the stationary platen 3, and a pulley 13a is fixed to a portion projecting forward from the stationary platen 3. Similarly, the ball screw 9b is rotatably supported by the moving platen 4 at a fixed position, and the pulley 13b is fixed to a portion protruding rearward from the moving platen 4.

The two ball screws 9 (a, b) are
The stationary platen 3 and the moving platen 4 are arranged in a straight line like a ball screw in the mold clamping unit 1 by the pivotal support and the support by the connecting member 10. On the other hand, a lockup servomotor 14 and a lockup brake 15 are attached to the stationary platen 3, and an output shaft 16 thereof and the pulley 1 are attached.
The timing belt 17 is wound around 3a. A servo motor 18 for feeding the mold and a feed stopping brake 19 are attached to the moving platen 4, and a timing belt 21 is wound around its output shaft 20 and the pulley 13b. The servo motor 14,
18 is placed under the control of a control device provided in the injection molding machine.

The mold clamping operation is performed as follows in the mold clamping process of the injection molding cycle. In the mold open state, the mold feeding servomotor 18 is driven and the ball screw 9b is rotated. At this time, since the coupling member 10 is fitted into the tie bar 5, the screwing portion 12 as a ball nut cannot rotate, the ball screw 9b moves the screwing portion 12 forward, and the moving platen 4 moves. Advance. The moving platen 4 is advanced to the mold touch position, and the mold touch position is determined by the control device.

The moving platen 4 is advanced at a high speed because the lead of the screw portion 11b of the ball screw 9b is large. However, the torque required for the die feed motor 18 is small enough to overcome the initial inertia when the moving platen 4 is moved. Moving platen 4
The required torque is even smaller because it is only against the sliding resistance during the movement.

At the die touch position, the servo motor 18 for feeding the die is stopped and at the same time, the feed stop brake 19 is operated to prevent the ball screw 9b from rotating in the reverse direction.
Then, the lockup motor 14 is driven and the ball screw 9a is driven and rotated. Thereby, the coupling member 1
0 is pulled forward, and the tie bar 5 connecting the stationary platen 3 and the moving platen 4 is slightly stretched to give a predetermined mold clamping force to the mold 8 (lock-up). The lockup force is maintained by operating the lockup brake 15. The lead of the ball screw 9b is made extremely small so that a large mold clamping force can be obtained with a motor having a small torque.

In the mold opening, first, the lockup brake 15 is released, and the lockup servomotor 14 reverses the ball screw 9a to move the moving platen 4 back to the mold touch position. Then,
The feed stop brake 19 is released, the mold feed servomotor 18 is rotated in the reverse direction, and the moving platen 4 is retracted to the mold open position.

With the above construction, the ball screws 9a and 9b in the mold clamping linear feed device 6 are joined by the joining member 10, so that the ball screw 9a and 9b are provided in the same manner as a conventional single ball screw having threaded portions with different leads. To function. Further, since the stationary platen 3 and the rear platen 4 are directly coupled to each other as the mold clamping linear feeding device 6, the number of the tie bars 5 can be reduced, and moreover, the two platen type mold clamping unit 1 can be obtained. . In the mold clamping operation method, the servo motors 14 and 18 may be operated simultaneously. [Injection Unit] The injection unit 2 (FIG. 2) has the same structure as the mold clamping unit 1.

A stationary plate 22 and a moving plate 23 are erected parallel to each other, and both plates 22 and 23 are
Are connected by two tie rods 24 which are parallel to each other and two linear feeders 25, 25 for injection (Fig. 3B).
The tie rod 24 and the linear feeders 25, 25 for injection are arranged on diagonal lines of the stationary plate 22 and the moving plate 23, respectively, as shown in the figure. The stationary plate 22 is fixed to the base 7, and the moving plate 23 is movable in the front-rear direction (left and right in the drawing).

A cylinder assembly 26 is mounted on the stationary plate 22, a screw sleeve 27 is rotatably supported on the front surface of the moving plate 23, and a base portion of a screw 28 mounted on the cylinder assembly 26 is attached to this. ing.

The linear feeder 25 for injection is composed of a ball screw mechanism, and two ball screws 29 (a, b) are supported by the connecting member 30 with their tips abutting each other. The coupling member 30 is fitted into the tie rod 24 and is movable back and forth without interfering with the screw 28 and the screw sleeve 27.
The threaded portion 31 (a, b) of (a, b) has a threaded portion 32 screwed together. The screw portion 31a of the ball screw 29a has a small lead, and the screw portion 3 of the ball screw 29b is
1b has a large lead. The threaded portion 32 of the coupling member 30 includes female threads corresponding to the threaded portions 31 (a, b), and corresponds to the ball nut of the ball screw 29 (a, b).

The ball screw 29a is rotatably supported by the stationary plate 22 at a fixed position, and the pulley 33a is provided at a portion projecting forward from the stationary plate 22.
Is fixed. Similarly, the ball screw 29b is rotatably supported at a fixed position on the moving plate 23, and the pulley 33b is fixed to a portion protruding rearward from the moving plate 23.

Also, two ball screws 29 (a, b)
Are arranged in a straight line like a ball screw in the injection unit 2 by the support of the stationary plate 22 and the moving plate 23 and the support of the coupling member 30. On the other hand, the stationary plate 22 has a servo motor 34 for injection pressure and an injection pressure brake 35.
Is attached to the output shaft 36 and the pulley 33a.
The timing belt 37 is wound around. A servo motor 38 for injection feed and a feed stop brake 39 are attached to the moving plate 23, and an output shaft 40 thereof and the timing belt 41 on the pulley 33b.
Is hung around. In addition, the screw sleeve 27
A pulley 42 is fixed to the output shaft 44 and an output shaft 44 of a measuring servomotor 43 attached to the moving plate 23 and is linked with a timing belt 45.
The injection pressure servo motor 34, the injection feed servo motor 38, and the weighing servo motor 43 are placed under the control of a control device provided in the injection molding machine.

The injection operation is performed as follows in the measurement / injection process of the injection molding cycle. The measuring servomotor 43 is driven and the screw 28 is rotated to perform the measurement. The injection feed servomotor 38 is rotated in the reverse direction. The force for pushing back the screw 28 by the pressure of the resin fed with the measurement and the servomotor 3 for injection feeding.
By the reverse rotation of 8, the moving plate 23 retracts and reaches the screw back position. The reverse rotation of the injection feed servomotor 38 is such that the screw 28 is resisted to some extent by the force to be pushed back to give a so-called back pressure.

When the measurement is completed, the injection feed servomotor 38 is rotated in the normal direction and the ball screw 29b is rotated.
On the other hand, the coupling member 30 as a ball nut cannot be rotated because it is inserted into the tie rod 24, and the ball screw 29
b moves forward. As a result, the moving plate 23 is advanced, and the screw 28 is fed from the screw back position to the filling completion position in this embodiment. The position where the filling is completed is determined by the control device. At the filling completion position, the injection feed servomotor 38 is stopped and the brake 38 is operated to prevent the ball screw 29b from rotating in the reverse direction.

Then, the injection pressure servomotor 34 is rotated in the normal direction and the ball screw 29a is rotated. As a result, the ball screw 29a draws the connecting member 30 as a ball nut, further advances the screw 28, and performs packing with a high injection pressure.

Moving plate 2 to the filling completion position
3 is advanced at high speed because the lead of the screw portion 31b of the ball screw 29b is large. However, the torque required for the injection feed motor 38 is small enough to overcome the resistance until the cavity of the mold is filled with the resin. The moving plate 23 is advanced after the filling position at a low speed but a large pressure because the lead of the ball screw 29a is small, and the pressure is maintained by this pressure.
The holding pressure is maintained by operating the injection pressure brake 35.

When the holding pressure is completed, the injection pressure brake 35 is released, the injection pressure servomotor 34 is reversed, and the ball screw 29a is reversed, so that the moving plate 23 is retracted to the filling position via the coupling member 30. Next, the metering servomotor 43 is driven, the feed stop brake 39 is released and the injection feed servomotor 38 is rotated in the reverse direction to give back pressure, the ball screw 29b is reversed, and the moving plate 23 is retracted. To be done. As a result, the screw 28 returns to the screw back position.

With the above structure, the linear feeder for injection 2
The ball screws 29a and 29b in FIG.
By being coupled with, it functions in the same manner as a conventional single ball screw having threaded portions with different leads. Further, since the stationary plate 22 and the moving plate 23 are directly coupled to each other as the linear feeding device 25 for injection, the number of the tie rods 24 can be reduced, and the two-plate type injection unit 2 can be obtained. In the injection operation method, the servo motors 34 and 38 may be operated simultaneously.

FIG. 4 is a second embodiment and relates to the mold clamping unit 1. The linear feeding device 6 for clamping the mold of the clamping unit 1 in the first embodiment is adopted in a mode in which the ball screw is driven, whereas the linear feeding device 6 for clamping in the second embodiment is adopted. It is adopted in a mode in which the ball nut is driven.

The same members as those in the first embodiment are designated by the same reference numerals, and the same structure will not be described in detail. The mold clamping linear feeding device 6 is composed of a ball screw mechanism, and the two ball screws 9 (a, b) are the screw parts 1
The tips other than 1 (a, b) are butted against each other and are non-rotatably supported by the coupling member 10. The threaded portion 12 of the coupling member 10 of the first embodiment is the ball nut 12 (a, b) in the second embodiment.

The ball nut 12a is rotatably supported by the stationary platen 3 at a fixed position so that the ball nut 1a
The moving platen 4 is rotatably supported at a fixed position by 2b. Further, the two ball screws 9 (a, b) are aligned in a straight line like one ball screw in the mold clamping unit 1 by the pivotal support by the stationary platen 3 and the moving platen 4 and the connecting member 10 at the abutting portion. It is located in.

A pulley 13a is fixed to the ball nut 12a at a portion of the stationary platen 3 projecting forward, and a pulley 13b is fixed to a portion of the ball plate 12b projecting to the rear of the moving platen 4. . On the other hand, a servo motor 14 for lockup is attached to the stationary platen 3, and the timing belt 1 is attached to the output shaft 16 and the pulley 13a.
7 is hung around. Further, a die feed servomotor 18 is attached to the moving platen 4, and a timing belt 21 is wound around its output shaft 20 and pulley 13b. The servomotors 14 and 18 are placed under the control of a control device provided in the injection molding machine.

The mold clamping operation is similar to that of the first embodiment, except that the ball nut is driven. When the die feed servomotor 18 is driven, the ball nut 12b moves the screw portion 11b of the ball screw 9b forward or backward, and the moving platen 4 moves forward or backward. When the lockup servomotor 14 is driven, the ball screw 9a is moved forward or backward by the rotation of the ball nut 12a, and the moving platen 4 is moved forward or backward.

The moving platen 4 is fed (forward / backward) at a high speed due to the large lead of the screw portion 11b of the ball screw 9b, but the required torque is small, and the lock-up operation is performed by the ball screw 9a. Although the lead of the screw portion 11a is extremely small and the speed is low, a large mold clamping force can be obtained with a motor having a small torque, as in the case of the first embodiment.

Also in this embodiment, the ball screws 9a and 9b in the mold clamping linear feeding device 6 are joined by the joining member 10 so that the ball screw 9a and 9b of the conventional die are provided with screw portions having different leads. Same function as ball screw, stationary platen 3 and moving platen 4
It is also the same that the number of the tie bars 5 can be reduced by directly connecting the two to each other as the linear feeding device 6 for mold clamping, and the two platen type mold clamping unit 1 can be obtained.

Further, in the second embodiment, the connecting member 10
It is possible to reduce the dimension in the front-rear direction of the coupling portion (the screwing portion 12 in the first embodiment) in (1) and reduce the wasted space in the mold clamping unit 1. Also with respect to the injection unit 2 of the first embodiment, the second of the mold clamping unit 1
Similar to the embodiment, the ball screw nut mechanism of the injection linear feeder 25 can be a ball nut drive type.

[Nozzle Touch Device] FIG. 5 relates to an injection molding machine using a linear feed device having a ball screw nut mechanism as the nozzle touch device in the third embodiment. The nozzle touch device 50 employs a touch linear feed device 51. In the ball screw nut mechanism of the linear feed device 51 for touch, two ball screws 53 (a, b) having screw parts 52 (a, b) with different leads are joined by abutting their tips, and the respective screw parts are connected. The structure is such that nuts 54 (a, b) corresponding to 52 (a, b) are provided.

The mold clamping unit 1 and the injection unit 2 are arranged on the base 7 so as to face each other, and the nozzle touch device 50 is arranged below the base 7. The injection unit 2 is movable back and forth on the base 7, and is connected to the nozzle touch device 50 by a connecting member 55 extending downward.

The front ball nut 54a of the nozzle touch device 50 is located below the base 7 in the mold clamping unit 1.
The front stay 56 fixed to the side is pivotally supported so as to rotate at a fixed position, and the screw portion 52a of the ball screw 53a is screwed to this. The rear ball nut 54b is screwed into the screw portion 52b of the rear ball screw 53b, and the rear end of the ball screw 53b rotates at a fixed position on the rear stay 57 fixed to the injection unit 2 side below the base 7. Is pivotally supported.

An intermediate stay 5 is further provided under the base 7.
8 is provided, and a cylindrical slider 59 is attached to this so as to be slidable in the front-rear direction. Slider 59
, The tip ends of both ball screws 53 (a, b), that is, the opposite sides of the screw parts 52 (a, b) are butted against each other and are non-rotatably attached. Also, the rear ball screw 52
The front end portion of b penetrates the connecting member 55 projecting downward from the injection unit 2 in the front-rear direction. Two ball screws 5
3 (a, b) are front, rear and middle stays 56,
The nozzle touch device 50 is arranged in a straight line like a ball screw by being supported by 57 and 58.

The front ball screw 54a is interlocked with a touch pressure motor 60 fixed to the base 7, and the rear ball nut 54b is interlocked with a unit feed motor 61 attached to the nut itself. Further, the rear ball nut 54b includes a flange 62,
Two guide bars 63 are arranged in the front-rear direction between the flange 62 and the connecting member 55 of the injection unit 2, and a touch pressure spring 64 is attached to the ball screw 53b. The touch pressure servomotor 60 includes a touch pressure brake 65, and the unit feed motor 61 includes a feed stop brake 66.

The nozzle touch device 50 operates as follows. When the injection unit 2 is in the retracted position, the unit feed motor 61 is driven to drive the ball nut 54 at the rear.
b is rotated, the touch pressure spring 64, the connecting member 5
The injection unit 2 is sent forward via 5. In this case, since the touch pressure brake 65 for the front ball screw 53b is activated, the rear ball screw 53
b cannot be rotated via the slider 59.

The nozzle at the tip of the cylinder assembly 26 is
When the touch position where the die contacts the sprue bush is reached, the unit feed motor 61 is stopped and the feed stop brake 66 is activated. The touch position is detected from a touch sensor, a limit switch, or the rotation amount of the motor 61 (in the case of a servo motor).

Then, the touch pressure motor 60 is driven to rotate the front ball nut 54a. As a result, the injection unit 2 is pulled further forward together with the rear ball screw 53b and the rear ball nut 54b. Actually, since the nozzle is in contact with the sprue bush, only the rear ball nut 54b moves forward,
The touch pressure spring 64 is compressed.

As a result, touch pressure is applied between the abutting nozzle and the sprue bush. The touch pressure motor 60 is stopped at a position where the spring 64 is compressed by a predetermined amount. At the same time, the injection pressure brake 65 is operated to maintain the injection pressure. The stop position is detected by detecting the position of the ball nut 54b with respect to the connecting member 55 with a limit switch or by the rotation amount of the motor 60 (in the case of a servo motor).

To release the nozzle touch, first, the touch pressure brake 65 is released and the touch pressure motor 60 is rotated in the reverse direction to release the touch pressure. Next, touch pressure brake 6
5 is operated to reverse the unit feed motor 61. As a result, the rear ball nut 54b moves rearward, and the injection unit 2 is moved to the retracted position via the guide rod 63.

As described above, the linear feeder for touch 51
The ball screws 53a and 53b in 1 are connected by a slider 59 as a connecting member, so that the ball screws 53a and 53b function similarly to a conventional single ball screw having screw portions with different leads.

FIGS. 6A and 6B show another embodiment of the linear feeding device 6, which is a structure for reducing the dimension in the front-rear direction. In (a), the tip of one ball screw 9a is inserted into the tip of the other ball screw 9b. In (b), the axes of the one ball screw 9a and the other ball screw 9b are displaced so that they do not interfere with each other.

The above is an embodiment, and the present invention is not limited to the illustrated specific configuration. The linear feed device that uses a ball screw nut mechanism in which the tips of two ball screws are butted against each other can also be used in other parts of an injection molding machine such as an eject device. The means for interlocking the linear feeding device and the motor may be a sprocket and a chain.

The transition point from high speed / low torque to low speed / high torque relating to the linear feeder can be set arbitrarily. In the embodiment, each linear feeding device is driven by two motors (servo motors), but the output of one motor may be switched by a clutch for use.

[0062]

Since two ordinary ball screws are used in combination, it is possible to obtain a linear feed device having screw portions with different leads at a low price. By using the linear feeder to connect the stationary platen and moving platen of the mold clamping unit or the stationary plate and moving plate of the injection unit, the two platen type mold clamping unit and the two plate type injection unit can be achieved with a simple structure. Therefore, the front-rear dimension of the injection molding machine can be shortened, high-precision finishing and expensive tie bars and tie rods can be shortened, and the number of them can be reduced. As a result, the cost of the injection molding machine can be reduced.

Normal high speed which is not special for linear feeders
By combining a low-torque motor and a low-speed / high-torque motor, it is possible to obtain the necessary feed speed and pressure at a low price without waste.

[Brief description of drawings]

FIG. 1 is a cross-sectional front view (a mold clamping unit, a first embodiment).

FIG. 2 is a cross-sectional front view (injection unit).

FIG. 3 is a front view.

FIG. 4 is a front view showing a section (a mold clamping unit, a second embodiment).

FIG. 5 is a front view showing a section of a nozzle touch device in section.

FIG. 6 is a sectional front view showing another example of the linear feeding device.

[Explanation of symbols]

 1 mold clamping unit 2 injection unit 3 stationary platen 4 moving platen 5 tie bar 6 linear feeder for mold clamping 7 base 8 mold 9 (a, b) ball screw 10 coupling member 11 (a, b) screw part 12 screwing part 13 (a, b) Pulley 14 Servo motor for lock up 15 Brake device for lock up 16 Output shaft 17 Timing belt 18 Servo motor for die feed 19 Feed stop brake 20 Output shaft 21 Timing belt

Claims (4)

[Claims] 1. A linear feed device for converting a rotary motion into a linear motion is constituted by a ball screw nut mechanism, and two ball screws each having a screw part with a different lead are joined together by abutting their tips, and each screw part is connected. An electric injection molding machine having a structure in which a nut corresponding to is screwed. 2. A two-platen type mold clamping unit in which a moving platen is connected to a stationary platen by a plurality of linear feed devices composed of a ball screw nut mechanism, and in each ball screw nut mechanism, the ball screw is a lead. Two screws with different screw parts are joined together by abutting the tips, and the nuts corresponding to each screw part are screwed together. The ball screw nut side with a small lead is connected to the lockup motor and the ball with a large lead is connected. An electric injection molding machine characterized in that the screw nut side is connected to a mold feed motor. 3. A two platen type injection unit in which a moving plate is connected to a stationary plate by a plurality of linear feed devices composed of a ball screw nut mechanism, and the ball screw has different leads in each ball screw nut mechanism. Two threaded parts are joined together with their ends abutted, and nuts corresponding to each threaded part are screwed together. The ball screw nut side with the small lead is connected to the injection pressure motor, and the ball screw nut with the large lead is connected. An electric injection molding machine whose side is connected to an injection feed motor. 4. An injection unit is coupled to a mold clamping unit by a nozzle touch mechanism using a linear feed device composed of a ball screw nut mechanism, and in the ball screw nut mechanism, the ball screw is provided with two screw portions having different leads. Are connected with their ends abutted, and nuts corresponding to each screw part are screwed together.The ball screw nut side with a small lead is connected to the touch pressure motor, and the ball screw nut side with a large lead is connected to the unit feed motor. An electric injection molding machine characterized by being used.