Speed-up mechanism for an injection molding machine

Abstract

A speed-up mechanism for an injection molding machine is disclosed, which has a front fixed plate having a through hole at the center; a rear fixed plate arranged parallel with the front fixed plate, and the rear fixed plate having at least one through hole; at least two guide bars parallel to each other arranged between the front fixed plate and the rear fixed plate in an equal distance; a movable plate slidably arranged on the guide bars between the front fixed plate and the rear fixed plate, and capable of moving toward and away; a rotatry power source fixed on one side of the movable plate for providing rotatry power, the rotatry power source comprising a transmission device; a fixed nut mounted on the rear fixed plate; at least one ball screw having two threads in opposite directions at two ends, the front end is engaged with the transmission device for generating a radial rotation, the rear end is engaged with the fixed nut and through the rear fixed plate to generate an axial movement for the ball screw during the rotation; and at least one movable nut engaged with the front end of the ball screw to move along the ball screw during the rotation of the ball screw, the outside of the movable nut is connected to the movable plate to drive the movable plate in the axial direction during the rotation of the ball screw.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an injection molding machine and, more particularly, to a speed-up mechanism for an injection molding machine.

[0003] 2. Description of the Related Art

[0004] In recent years, in order to generate more accurately injected product, the injection molding machine needs high respondence and high performance to achieve high accurately injected products and high cycle molding requirements. The prior art injection molding machine utilizes a servomotor to drive a ball screw, the ball screw and a fixed nut linearly relatively move to operate a mold clamping process. However, the relative movement between the ball screw and the fixed nut generates high abrasion, which causes the injection molding machine incapable of high respondence and high rate performance.

[0005] Therefore, it is desirable to provide an improved injection molding machine to obviate the aforementioned problems.

SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide a speed-up mechanism for an injection molding machine to improve the injecting speed. The speed-up mechanism is easy to manufacture, to assemble, and the speed-up mechanism is capable of high respondence and high performance.

[0007] To achieve the objective, the speed-up mechanism of the present invention includes: a front fixed plate having a through hole at the center; a rear fixed plate arranged parallel with the front fixed plate, and the rear fixed plate having at least one through hole; at least two guide bars parallel to each other arranged between the front fixed plate and the rear fixed plate in an equal distance; a movable plate slidably arranged on the guide bars between the front fixed plate and the rear fixed plate, and capable of moving toward and away; a rotatry power source fixedly attached on one side of the movable plate for providing rotatry power, the rotatry power source comprising a transmission device; a fixed nut mounted on the rear fixed plate; at least one ball screw having two threads in opposite directions at two ends, the front end is engaged with the transmission device for generating a radial rotation, the rear end is engaged with the fixed nut and through the rear fixed plate to generate an axial movement for the ball screw during the rotation; and at least one movable nut engaged with the front end of the ball screw to move along the ball screw during the rotation of the ball screw, the outside of the movable nut is connected to the movable plate to drive the movable plate in the axial direction during the rotation of the ball screw.

[0008] Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a side sectional view, of the speed-up mechanism for an injection molding machine of the present invention.

[0010] FIG. 2 is a top view of the speed-up mechanism for an injection molding machine of the present invention.

[0011] FIG. 3 is a partial magnify drawing of the elements of the speed-up mechanism for an injection molding machine of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] Please refer to FIG. 1 and FIG. 2. FIG. 1 is a side sectional view of the speed-up mechanism for an injection molding machine of the present invention. FIG. 2 is a top view of the speed-up mechanism for an injection molding machine of the present invention. The speed-up mechanism of the present invention comprises: a front fixed plate 8 having a through hole at the center; a rear fixed plate 4 arranged parallel with the front fixed plate 8, and the rear fixed plate 4 having at least one through hole; two guide bars 7, 7′ parallel to each other arranged between the front fixed plate 8 and the rear fixed plate 4 in an equal distance; a movable plate 1 slidably arranged on the guide bars 7, 7′ between the front fixed plate and the rear fixed plate, and capable of moving toward and away; a rotatry power source 2 fixed on one side of the movable plate 1 for providing rotatry power, the rotatry power source 2 comprising a transmission device; a fixed nut 5 mounted on the rear fixed plate 4; a ball screw 3 having two threads in opposite thread directions at two ends, the front end is engaged with the transmission device for generating a radial rotation, the rear end is engaged with the fixed nut 5 and through the rear fixed plate 4 to generate an axial movement for the ball screw 3 during the rotation; and a movable nut 6 engaged with the front end of the ball screw 3 to move along the ball screw 3 during the rotation of the ball screw 3, the outside of the movable nut 6 is connected to the movable plate 1 to drive the movable plate 1 in the axial direction during the rotation of the ball screw 3.

[0013] The rotatry power source 2 may be a servomotor, an induction motor, or an oil pressure motor. The transmission device comprises a timing belt 11 and a conical constrictive ring 12. And an output shaft of the rotatry power source 2 further comprises a driving wheel 13. Furthermore, the front of the ball screw 3 is connected to a transmission rod 16, and the transmission rod 16 further comprises a driven wheel 14. So the rotatry power from the driving wheel 13 of the rotatry power source 2 is transmitted to the driven wheel 14 via the timing belt 11 and a conical constrictive ring 12 of the transmission device 10. In additional, the transmission device 10 may be a gear combination.

[0014] Please refer to FIG. 3. FIG. 3 is a partial magnify drawing of the elements of the speed-up mechanism for an injection molding machine of the present invention. The front fixed plate 8 and the rear fixed plate 4 are used as a support frame for the speed-up mechanism of the present invention, and two guide bars 7, 7′ are arranged between the front fixed plate 8 and the rear fixed plate 4 to guide the movable plate 1 toward and away. The driving wheel 13 of the rotatry power source 2 fixed on the movable plate 1 forces the ball screw 3 to rotate via the driven wheel 14, the timing belt 11, the conical constrictive ring 12 of the transmission device 10. Then the fixed nut 5 mounted on the rear fixed plate 4 transmits the rotation force to move the movable plate 1 toward and away so an injecting screw 17 carries injection, pressure holding, and back-pressure for the injection molding machine.

[0015] The present invention can also be applied to a large-scale injection molding machine. However, one single ball screw may not bear the retaining pressure of injection, the number of the ball screw can be plurality. And the plurality of the ball screws can be driven by a plurality of electric motor via a gear combination.

[0016] The main objective of the present invention is to utilize the rotatry power source 2 fixed on the movable plate 1 to rotate the ball screw 3, then the ball screw 3 drives the fixed nut 5 mounted on the rear fixed plate 4 to rotate. So the ball screw 3 generates an axial velocity V35 and an acceleration A35 relative to the fixed nut 5. Furthermore, due to the rotation of the ball screw 3, the movable nut 6 generates an axial velocity V63 and an acceleration A63. Since the thread 32 of the movable nut 6 is opposite to the thread 31 of the fixed nut 5. The axial Velocity V35 and the axial Velocity V63 of the movable nut 6 are acting on the transmission rod 16 at the same direction. Therefore, the movable plate 1 moving on two guide bars 7, 7′ has a axial Velocity V65: V63+V35=V65 and an acceleration A65: A63+A35=A65, relative to the fixed nut 5 to speed-up injecting screw 17 of the injection molding machine.

[0017] The present invention provides a screw type speed-up mechanism driven by the rotatry power source, which cause the movable plate to drive the injection screw to perform pressure holding and measuring movement due to the relative velocity between the screw and the fixed nut 5 and the movable nut 6. The speed-up mechanism for an injection molding machine of the present invention obtains a first velocity and a first acceleration from the relative movement between the ball screw and the fixed nut, and further obtains a secondary velocity and a secondary acceleration from the relative movement between the ball screw and the movable nut. Therefore, the speed-up mechanism of the present invention is capable of high respondence and high performance.

[0018] The present invention utilizes a power unit to drive the speed-up mechanism; the speed-up mechanism speeds up the injecting screw due to two relative axial velocities and acceleration generated by the threads on two ends of the screw and the fixed nut and the movable nut. Therefore, the present invention achieves high acceleration and high performance and overcomes the high abrasion disadvantage of the prior art injection molding machine.

[0019] Although the present invention has been explained in relative to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.

Claims

1. A speed-up mechanism for an injection molding machine, the mechanism comprising: a front fixed plate having a through hole at the center; a rear fixed plate arranged parallel with the front fixed plate, and the rear fixed plate having at least one through hole; at least two guide bars parallel to each other arranged between the front fixed plate and the rear fixed plate in an equal distance; a movable plate slidably arranged on the guide bars between the front fixed plate and the rear fixed plate, and capable of moving toward and away; a rotatry power source fixed on one side of the movable plate for providing rotatry power, the rotatry power source comprising a transmission device; a fixed nut mounted on the rear fixed plate; at least one ball screw having two threads in opposite thread directions at two ends, the front end is engaged with the transmission device for generating a radial rotation, the rear end is engaged with the fixed nut and through the rear fixed plate to generate an axial movement for the ball screw during the rotation; and at least one movable nut engaged with the front end of the ball screw to move along the ball screw during the rotation of the ball screw, the outside of the movable nut is connected to the movable plate to drive the movable plate in the axial direction during the rotation of the ball screw.

2. The speed-up mechanism as claimed in claim 1, wherein when the rotatry power source rotates the ball screw in a predetermined direction relatively to the fixed nut on the rear fixed plate via the transmission device cause the movable nut to rotate in the opposite direction to drive the movable plate on the guide bars.

3. The speed-up mechanism as claimed in claim 1, wherein the threads on the two ends of the ball screw have the same lead or different leads.

4. The speed-up mechanism as claimed in claim 1, wherein the rotatry power source is a servomotor.

5. The speed-up mechanism as claimed in claim 1, wherein the rotatry power source is an induction motor.

6. The speed-up mechanism as claimed in claim 1, wherein the rotatry power source is an oil pressure motor.

7. The speed-up mechanism as claimed in claim 1, wherein the front of the ball screw is connected to a transmission rod.

8. The speed-up mechanism as claimed in claim 2, wherein the transmission device comprises a timing belt and a conical constrictive ring, and a output shaft of the rotatry power source further comprises a driving wheel, the transmission rod connected to the front end of the ball screw further comprises a driven wheel, so the rotatry power from the driving wheel of the rotatry power source is transmitted to the driven wheel via the timing belt and a conical constrictive ring of the transmission device.

9. The speed-up mechanism as claimed in claim 2, wherein the transmission device is a gear combination.

10. A speed-up mechanism for an injection molding machine, the mechanism comprising: a front fixed plate having a through hole at the center; a rear fixed plate arranged parallel with the front fixed plate, and the rear fixed plate having at least one through hole; at least two guide bars arranged between the front fixed plate and the rear fixed plate in an equally distance; a movable plate slidably arranged on the guide bars between the front fixed plate and the rear fixed plate, and capable of moving toward and away; a fixed nut mounted on the rear fixed plate; a ball screw having two threads in opposite directions at two ends, the front end is engaged with a transmission device for generating a radial rotation, the rear end is engaged with the fixed nut and through the rear fixed plate to generate an axial movement for the ball screw during the rotation; and a movable nut engaged with the front end of the ball screw to move along the ball screw during the rotation of the ball screw, the outside of the movable nut is connected to the movable plate to drive the movable plate in axial direction during the rotation of the ball screw.

11. The speed-up mechanism as claimed in claim 10, wherein the threads on the two ends of the ball screw have the same lead or different leads.

12. The speed-up mechanism as claimed in claim 10, wherein the front of the ball screw is connected to a transmission rod.

13. The speed-up mechanism as claimed in claim 10, wherein the transmission device comprises a timing belt and a conical constrictive ring, and a output shaft of the rotatry power source further comprises a driving wheel, the transmission rod connected to the front end of the ball screw further comprises a driven wheel, so the rotatry power from the driving wheel of the rotatry power source is transmitted to the driven wheel via the timing belt and a conical constrictive ring of the transmission device.

14. The speed-up mechanism as claimed in claim 10, wherein the transmission device is a gear combination.