JP4626870B2 - Drive unit for injection molding machine - Google Patents

Description

  The present invention relates to a drive device for an injection molding machine that injects, for example, molten resin into a molding cavity of a mold.

  2. Description of the Related Art Conventionally, as a drive device for an injection molding machine, a drive mechanism comprising a structure in which a transmission timing pulley is attached to a screw shaft of a ball screw mechanism, a transmission timing belt is wound around the transmission timing pulley, and the transmission timing belt is driven by an electric motor. There is a drive device that drives a movable member that is linearly movable by these drive mechanisms. This drive device is provided with a synchronous timing belt that synchronizes the rotation of the screw shaft of each ball screw mechanism provided in each of the plurality of drive mechanisms, and this synchronous timing belt is attached to the screw shaft of each ball screw mechanism. Each is wound around an associated synchronous timing pulley.

  In the drive mechanism described above, the transmission timing pulley around which the transmission timing belt is wound and the synchronization timing pulley around which the synchronization timing belt is wound are separate pulley members, each in a state of being overlapped with the end of the same screw shaft. It is attached. At this time, the synchronous timing pulley is arranged closer to the tip of the screw shaft than the transmission timing pulley, and when viewed from the side, the synchronous timing pulley is at the front and the transmission timing pulley is at the back of the synchronous timing pulley. Has been placed. In addition, the synchronous timing pulley has a smaller diameter than the transmission timing pulley in order to reduce the moment of inertia of the entire driving device and facilitate the mounting and replacement work of the transmission timing belt. (For example, refer to Patent Document 1).

By the way, when the timing belt with teeth is wound around the pulley, if the teeth of the timing belt and the teeth of the pulley are meshed with no gap, the meshed teeth are caught and the timing belt and the pulley cannot rotate smoothly. In view of this, it is necessary to create a gap (backlash) in the transmission direction at the meshing location. The magnitude of this backlash is generally proportional to the timing belt tooth pitch.
In addition, in an electric injection molding machine, there is a pressure holding process that keeps pressing the screw at the injection shaft screw and the resin material at the tip of the screw at a constant pressure. During this pressure holding process, the motor is finely reversed. Repeated driving.
Japanese Patent No. 3496089

However, in the above-described conventional injection molding machine drive device, the transmission timing pulley and the synchronous timing pulley are separate parts, so the structure for fixing each pulley coaxially becomes complicated, and the assembly of each pulley is also difficult. However, there is a problem that stable power transmission cannot be performed if the accuracy of the concentricity between the transmission timing pulley and the synchronous timing pulley is poor.
In addition, in the conventional injection molding machine drive device, when trying to manufacture a pulley in which the transmission timing pulley and the synchronous timing pulley are integrated, the diameters of the transmission timing pulley and the synchronous timing pulley are different. There is a problem that it is very difficult to process.

  Furthermore, if the synchronous timing pulley has a smaller diameter than the transmission timing pulley as in the conventional injection molding machine drive device described above, the synchronous timing belt has a larger synchronization timing than the transmission timing pulley in order to improve the transmission capability of the synchronous timing belt. A pulley is often used, and in this case, backlash on the synchronous timing pulley is increased. When a synchronous timing pulley having the same pitch as the transmission timing pulley is used, if the synchronous timing pulley diameter is r, the backlash on the synchronous timing pulley is δ, and the transmission timing pulley diameter is R, The backlash Δ is R / r × δ, and the backlash on the transmission timing pulley increases. That is, in any of the cases described above, there is a problem that backlash on one of the pulleys becomes large, which becomes an obstacle to accurate control.

  The present invention takes the above-described conventional problems into consideration, simplifies the configuration of the apparatus to facilitate the assembly of the apparatus, enables stable transmission, and further facilitates processing. It aims at providing the drive device of the injection molding machine which can aim at cost reduction by comprising. It is another object of the present invention to provide a drive device for an injection molding machine that can perform accurate control without causing a deviation during the pressure holding process.

According to the first aspect of the present invention, a transmission timing belt driven by an electric motor is wound around a transmission timing pulley attached to a screw shaft of the ball screw mechanism, and the rotary motion by the electric motor is converted into a linear motion by the ball screw mechanism. A plurality of drive mechanisms configured to convert are provided, and a synchronization timing belt for synchronizing the rotation of the screw shaft of each ball screw mechanism provided in each of the plurality of drive mechanisms is provided. In the drive device of the injection molding machine that linearly drives the movable member by each provided ball screw mechanism, each transmission timing pulley provided in each of the plurality of drive mechanisms is integrally formed with the same pitch and the same outer diameter. equipped with two pulleys, the electric timing belt and the synchronous tie to the two pulleys Nguberuto is wound, respectively, the synchronization timing belt is not connected to the motor, is characterized in that said is wound between each transmission timing pulleys.

  Due to such a feature, the transmission timing pulley is a combination of a pulley around which the transmission timing belt is wound and a pulley around which the synchronization timing belt is wound, and there is no need to separately provide a pulley around which the synchronization timing belt is wound. The transmission timing belt and the synchronous timing belt are respectively wound around pulleys having the same pitch and the same diameter, and backlash on one belt side does not increase. Moreover, since the pulleys around which both belts are wound have the same diameter, it is possible to attach or replace the belt wound around the back.

  According to the driving apparatus for an injection molding machine according to the present invention, the structure of the apparatus can be simplified to facilitate the assembly of the apparatus, stable transmission can be achieved, and parts that can be processed more easily. By configuring, the cost can be reduced. In addition, there is no deviation during the pressure holding process, and accurate control can be performed.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an injection molding machine drive device according to the present invention will be described below with reference to the drawings.

  The embodiment of the drive device for an injection molding machine according to the present invention will be described with reference to the accompanying drawings with respect to an example in which the drive device for moving the injection screw of the injection device back and forth is applied. FIG. 1 and FIG. 2 show an embodiment of the present invention. A driving device A of this injection molding machine is a pair of a front plate 2 and a rear plate 3 to which a heating cylinder 1 is fixed. A pusher plate (movable member) 7 having an injection screw 6 rotatably attached to the guide rod 4 is supported so as to be movable in the axial direction of the injection screw 6, and the pusher plate 7 is supported by a pair of drive mechanisms 30, 30. By moving forward together with the injection screw 6, the molten resin is injected from the nozzle (not shown) of the heating cylinder 1 into the molding cavity of the mold. Further, the driving device A includes a synchronization mechanism 22 that synchronizes the driving of the pair of driving mechanisms 30 and 30.

  Each drive mechanism 30, 30 is configured to operate the ball screw mechanism 11, 11 via the speed reduction transmission device 10, 10 by an electric motor 8, 8 such as a servo motor fixed to the rear plate 3, that is, a ball screw mechanism. The transmission timing belts 16 and 16 driven by the electric motors 8 and 8 are wound around the transmission timing pulleys 15 and 15 attached to the screw shafts 14 and 14 of the eleventh and elevenths 11 and 11, respectively, and the rotational motion by the electric motors 8 and 8 is ball screw. Each of the mechanisms 11 and 11 is configured to be converted into a linear motion.

  The ball screw mechanism 11 includes a screw shaft 14 that is rotatably supported at both ends by the front plate 2 and the rear plate 3, and a ball nut 18 that is fixed to the pusher plate 7 and screwed to the screw shaft 14. ing.

  The reduction gear transmission 10 includes a small-diameter transmission timing pulley 13 attached to the output shaft 8a of the electric motor 8, a large-diameter transmission timing pulley 15 attached to the screw shaft 14 of the ball screw mechanism 11, a transmission timing pulley 13, and A transmission timing belt 16 is wound around the transmission timing pulley 15 and wound between the pulleys 13 and 15.

In the synchronization mechanism 22, a synchronization timing belt 21 that synchronizes the rotation of the screw shaft 14 of each ball screw mechanism 11 is wound between large-diameter transmission timing pulleys 15 and 15 provided in the pair of drive mechanisms 30 and 30, respectively. It is composed of The transmission timing pulley 15 attached to the screw shaft 14 has a width that allows at least the transmission timing belt 16 and the synchronization timing belt 21 provided in the synchronization mechanism 22 to be wound in parallel. , 15, a synchronous timing belt 21 is wound around the transmission timing belts 16, 16, respectively.
Reference numeral 24 denotes a tension pulley that adjusts the tension of the synchronous timing belt 21 and is moved in the radial direction by the adjusting member 25.

Next, the operation of the driving device A of the injection molding machine having the above-described configuration will be described.
When the electric motors 8 and 8 are actuated, power is transmitted to the ball screw mechanisms 11 and 11 via the speed reduction transmissions 10 and 10, respectively. Specifically, when the electric motor is operated, the small-diameter transmission timing pulley 13 attached to the output shaft 8a of the electric motor 8 rotates, the transmission timing belt 16 is driven, the large-diameter transmission timing pulley 15 rotates, and the ball The screw shaft 14 of the screw mechanism 11 rotates. When the screw shafts 14, 14 of the pair of ball screw mechanisms 11, 11 rotate, the pusher plate 7 attached to each ball nut 18, 18 follows the rotation direction of the motors 8, 8 together with the injection screw 6, and guides It moves forward or backward along the rods 4 and 4. At this time, since the synchronization mechanism 22 synchronizes the rotation of the screw shafts 14 and 14 of the both ball screw mechanisms 11 and 11, the ball nuts 18 and 18 of the both ball screw mechanisms 11 and 11 can be accurately and without deviation from each other. The pusher plate 7 moves smoothly and moves smoothly. Moreover, when performing the pressure-holding process which continues pressing the injection screw 6 and the resin material (not shown) at the tip of the injection screw 6 with a constant pressure, the motors 8 and 8 are repeatedly operated in a fine forward / reverse direction.

  According to the drive apparatus for an injection molding machine having the above-described configuration, the transmission timing pulley 15 is a combination of a pulley around which the transmission timing belt 16 is wound and a pulley around which the synchronous timing belt 21 is wound. The transmission timing belt 16 and the synchronization timing belt 21 are respectively wound around pulleys having the same pitch and the same diameter. As a result, there is only one pulley around which the transmission timing belt 16 and the synchronous timing belt 21 are wound, so that the configuration of the drive device of the injection molding machine can be simplified and the assembly of the device can be facilitated. The transmission timing pulley 15 can be easily processed and the cost can be reduced without the necessity of forming pulleys in two stages.

In addition, since the backlash on either one of the transmission timing belt 16 and the synchronous timing belt 21 does not increase, there is no deviation during the pressure-holding process, and accurate control can be performed.
Furthermore, since the pulley around which the transmission timing belt 16 and the synchronous timing belt 21 are wound has the same diameter, the transmission timing belt 16 wound around the back can be attached or replaced.

  As mentioned above, although embodiment of the drive device of the injection molding machine concerning this invention was described, this invention is not limited to above-described embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in the above-described embodiment, the transmission timing belt 16 includes the small-diameter transmission timing pulley 13 attached to the output shaft 8 a of the electric motor 8 and the large-diameter transmission timing pulley attached to the screw shaft 14 of the ball screw mechanism 11. However, in the present invention, the transmission timing belt is provided on a transmission timing pulley provided in addition to the output shaft of the electric motor and on the screw shaft of the ball screw mechanism. A configuration in which a transmission timing pulley wound around a timing pulley and attached to other than the output shaft of the motor is linked to a transmission timing pulley attached to the output shaft of the motor via another belt or pulley. It may be.

  In the above-described embodiment, each ball screw mechanism 11 of the driving device A is configured such that the ball nut 18 is moved by the rotation of the screw shaft 14, but the ball screw shaft is rotated by the rotation of the ball nut. The structure can move together with the pusher plate 7. In the above-described embodiment, the pusher plate 7 as a movable member for moving the injection screw 6 of the injection device back and forth is driven by the ball screw mechanisms 11 and 11 of the drive device. Instead, the movable plate of the mold clamping device may be configured to drive the mold clamping device (movable member) directly or via a toggle mechanism by the ball screw mechanisms 11 and 11, and the ejector plate of the ejector device. The (movable member) may be configured to be driven directly or indirectly. In this case as well, as in the driving device of the injection device, each of the movable members moves smoothly by the accurate synchronous rotation of the ball screw mechanisms 11 and 11 to cope with an increase in the size of the device (an increase in load). obtain.

It is a front view which shows embodiment of the drive device of the injection molding machine which concerns on this invention. FIG. 2 is a developed cross-sectional view of the drive device illustrated in FIG. 1.

Explanation of symbols

7 Pusher plate (movable member)
8 Electric motor 11 Ball screw mechanism 14 Screw shaft 15 Transmission timing pulley 16 Transmission timing belt 21 Synchronous timing belt 30 Drive mechanism A Drive unit for injection molding machine

Claims (1)

A drive mechanism having a configuration in which a transmission timing belt driven by an electric motor is wound around a transmission timing pulley attached to a screw shaft of the ball screw mechanism, and a rotational motion by the electric motor is converted into a linear motion by the ball screw mechanism. There are several, and
A synchronous timing belt for synchronizing the rotation of the screw shaft of each ball screw mechanism provided in each of the plurality of drive mechanisms;
In the drive device of the injection molding machine that linearly drives the movable member by each ball screw mechanism provided in each of the plurality of drive mechanisms,
Each transmission timing pulley provided in each of the plurality of drive mechanisms includes two pulleys integrally formed with the same pitch and the same outer diameter, and the electric timing belt and the synchronous timing belt are respectively connected to the two pulleys. The drive device for an injection molding machine, wherein the synchronous timing belt is wound and is not connected to an electric motor but is wound between the transmission timing pulleys.

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