JP4599331B2 - Electric injection molding machine - Google Patents

Description

  The present invention relates to an electric injection molding machine including an injection device or a mold clamping device using an electric motor as a drive source.

In the conventional electric injection device, the rear end of the screw in the injection heating cylinder is rotatably held between the front plate having the injection heating cylinder and the rear plate having the electric motor for driving the injection. A plate (injection plate) is provided so that it can be moved forward and backward, and the front and rear plates are connected by a tie bar provided through the intermediate plate, and injection drive means for converting the rotation of the electric motor into linear motion is provided between the rear plate and the injection plate. ing. Further, as an injection pressure measuring means, an annular strain detector having a half member bolted to a tie bar is attached. Further, even in an electric mold clamping device that performs mold opening / closing and clamping by a toggle mechanism, an annular strain detector is attached to the tie bar as means for detecting the mold clamping force.
JP 2000-246773 A JP 2001-315131 A

  When detecting the injection pressure, back pressure, mold clamping force, etc. due to tie bar distortion, the tie bar is installed through the intermediate plate and movable plate. Detection accuracy tends to decrease due to frictional resistance. In addition, since the amount of strain due to the elongation of the tie bar varies depending on the cross-sectional area and length, the tie bar diameter is reduced with the reduction in the distance between the plates or the distance between the panels due to the miniaturization of the injection device, so that elongation corresponding to the pressure occurs It is necessary to. However, since the strain detector attached to the tie bar is standardized in accordance with the tie bar diameter of general-purpose molding machines, the strain detector cannot be attached to a small tie bar that is not standardized and is compatible. Such downsizing is technically difficult and expensive in terms of mounting accuracy and detection accuracy.

  The object of the present invention is to solve the problem of tie bars associated with the miniaturization of injection devices and mold clamping devices by adopting steel bars, in which a part of a round bar is formed in a plate-like part, to a tie bar. A standard strain detector can be attached to the tie bar, and the injection pressure, back pressure and clamping force can be accurately measured from the amount of strain of the tie bar. Is to provide a simple electric injection device.

  According to the present invention, the front plate with the injection heating cylinder and the rear plate with the electric injection driving means attached are connected by a tie bar, and the injection plate is connected between the two plates with the injection driving means so as to freely move forward and backward. A mold clamping device that is connected to the stationary platen and the pressure receiving plate with the electric mold clamping drive means by a tie bar, and the movable platen is connected to the mold clamping drive means between the two plates so as to be movable forward and backward. In the injection molding machine provided, the tie bar of the injection device and / or the mold clamping device is formed into a plate-like portion in which the side surface excluding both ends of the round bar is formed into a long flat surface and the cross-sectional area is partially reduced. In this case, a strain detector is attached to the plate-like portion.

  In addition, the plate-like portion is formed to be long at one end of the round bar, and the tie-bar is arranged with the plate-like portion side as the rear plate or the pressure platen side. The plate and the movable platen have an insertion hole for the tie bar, and the diameter of the insertion hole is formed larger than the diameter of the tie bar so that the load of the injection plate or the movable plate does not interfere with the tie bar.

  In the above configuration, even if the tie bar is a round steel bar, it is possible to generate elongation corresponding to the injection pressure, back pressure, mold clamping force, etc. set from the cross-sectional area and length of the plate-like part. Therefore, even if the injection device or the mold clamping device is downsized, it is not necessary to use a small-diameter tie bar. In addition, since the plate-like part is a flat surface, a flat standard strain detector can be attached to the plate-like part to detect the amount of distortion, so the distance between the plates of the injection device and the distance between the plates of the clamping device can be reduced. Even with a very short ultra-small molding machine (for example, a clamping force of 10 KN or less), pressure measurements such as injection pressure, back pressure, and clamping force can be reliably performed from the elongation of the tie bar.

  In addition, the tie bar insertion hole of the injection plate and movable plate is made larger than the tie bar diameter so that the load does not interfere with the tie bar. Without being affected by the resistance, the pressure can be detected with high accuracy by the amount of distortion of the plate-like portion.

  In the figure, reference numeral 1 denotes an injection device which comprises a front plate 12 and a rear plate 13 whose main bodies are connected by four tie bars 11, 11, and an injection plate 14 which is provided between the two plates through the tie bars 11, 11. Each plate of the main body is supported by linear guide rails 20 laid on both sides of the upper surface of the machine base 2 and is movably placed on the machine base.

  An injection heating cylinder 15 having a screw interior is attached to the front center of the front plate 12, and an electric motor 16 for injection driving by a servo motor and an injection driving for rotation driven by the electric motor 16 are attached to the rear plate 13. A ball screw shaft 17 is attached. The ball screw shaft 17 is horizontally supported at the center of the rear plate 13 so as to be rotatable inward, and a pulley 17a is attached to a shaft end protruding outside the plate. The ball screw shaft 17 is rotationally driven by a transmission belt wound around the pulley 17 a and the pulley 16 a of the electric motor 16.

  The injection plate 14 includes a rotation shaft 18 in the center of the plate and a ball nut member 19 attached to the rear surface of the plate. A rotating shaft 18 is provided with a rear end of an injection screw 15 a protruding from the rear portion of the injection heating cylinder 15 and a pulley 18 a for transmitting the rotation of a metering electric motor (not shown). The ball screw shaft 17 is screwed. Further, the insertion hole 14 ′ of the tie bar 11 formed in the plate is formed with a diameter larger than the tie bar diameter so that the plate load does not interfere with the tie bar 11.

  3 is a mold clamping device, which is composed of a fixed plate 32 and a pressure receiving plate 33 in which the main body is connected by four tie bars 31 and 31, and a movable plate 34 provided between the two plates through the tie bars 31 and 31. Each panel of the main body is supported by linear guide rails 20 laid on both sides of the upper surface of the machine base 2 and is movably placed on the machine base.

  The stationary platen 32 includes a fixed mold 32a, and the pressure receiving plate 33 includes an electric motor 35 for clamping driving by a servo motor, and a ball screw shaft 36 for clamping clamping driven by the electric motor 35. . The ball screw shaft 36 is horizontally supported at the center of the pressure receiving plate 33 so as to be rotatable inwardly, and a pulley 36a is attached to a shaft end protruding outside the plate. The ball screw shaft 36 is rotationally driven by a transmission belt wound around the pulley 36 a and the pulley 35 a of the electric motor 35.

  The movable platen 34 includes a movable die 34 a, and the insertion hole 34 ′ of the tie bar 31 drilled in the plate is formed larger in diameter than the tie bar diameter so that the plate load does not interfere with the tie bar 31. A toggle mechanism 37 for clamping is provided between the movable plate 34 and the pressure receiving plate 33. The toggle mechanism 37 includes a cross head 37a having a ball nut screwed into the ball screw shaft 36 therein. The toggle link 37b is connected to the cross head 37a and bends and stretches each time it moves forward and backward.

  The tie bars 11 and 31 are of the same specification, and as shown in FIG. 3, both side surfaces excluding both end portions 11a and 31a of the round bar are shifted to one end portion to form a long flat surface, and the cross-sectional area is partially It consists of a steel bar formed on the plate-like portions 11b and 31b which are reduced in number. In this tie bar, the plate-like portions 11b and 31b are stretched and distorted by the tensile force, so that the amount of elongation can be set by the cross-sectional area and length of the plate-like portion. Further, since both end portions are round bars, both end portions can be inserted into both plates and both boards and fastened with nut members in the same manner as a normal tie bar.

  The tie bars 11 and 31 are arranged on the plate 12 side after the electric motor 16 is attached in the injection apparatus 1 and on the pressure receiving plate 33 side where the electric motor 35 is attached in the mold clamping apparatus 4. The standard strain detector 21 (Minevea tie bar sensor: UX010) is attached to the plate-like portion by bolts. As a result, it is possible to detect the distortion caused by the extension of the tie bars 11 and 31 due to the external force, and to easily and accurately measure the pressure such as the injection pressure, the back pressure, and the mold clamping force from the distortion amount.

  In the injection apparatus configured as described above, the rotary shaft 22 is inserted into the lower portion of the main body, the screw shaft portion 22a is screwed to the front plate 12, and the tip is connected to the nozzle touch generator 23 by the spring member attached to the fixed plate 32. The nozzle touch can be performed by a nozzle touch mechanism using the electric motor 24.

  In the injection device 1, in the nozzle touch state shown in FIG. 1, when the injection plate 14 moves forward together with the injection screw 15a by the rotation of the ball screw shaft 17 and injects the measured molten resin in the injection heating cylinder, A reaction force acts on the rear plate 13 via the ball screw shaft 17. Since the rear plate 13 is not fixed on the machine base but supported by the linear guide rail 20 together with the front plate 12 and is connected to the front plate 12 by the tie bars 11, 11, the reaction force is pulled on the tie bars 11, 11. It concentrates as a force, and the plate-like portion 11b extends to generate distortion.

  Also, during plasticization and weighing of the resin by the rotation of the injection screw 15a, the backward movement of the injection plate 13 is controlled by the rotation control of the ball screw shaft 17, and a back pressure corresponding to the resin pressure is generated. The reaction force of the back pressure acts on the rear plate 13. As a result, the plate-like portion 11b of the tie bar 11 is pulled to cause distortion as in the case of injection. The strain amount of the plate-like portion 11b is detected by the strain detector 21. Since the amount of strain due to tension varies depending on the injection pressure and back pressure, the injection pressure and back pressure can be measured from the amount of strain detected there.

  In the above mold clamping apparatus, when the ball screw shaft 36 rotates in the mold open state shown in FIG. 1, the cross head 37a moves forward, the toggle mechanism 37 extends, and the movable plate 34 moves forward to move with the fixed mold 32a. The mold 34a is closed, and the movable platen 34 pressurizes the fixed platen 32 through the mold. As a result, the tie bars 31, 31 are pulled and stretched, and the elastic force generated by the stretch acts on the mold as a mold clamping force. Since distortion due to the extension of the tie bar mainly occurs in the plate-like portion 31b, the amount of distortion of the plate-like portion 31b can be detected by the strain detector 21 to measure the clamping force. Further, the amount of contraction of the tie bars 31, 31 generated by the mold opening due to the bending operation of the toggle mechanism 37 can also be detected by the detector 21.

  Although not shown, the strain detector 21 may be attached to the tie bars 11 and 31 on both sides, and in this case, the average value of strain amounts detected from both can be used as the detected value. The accuracy of measurement is further improved. In addition, the ball screw shaft of the injection drive means is a single shaft, but it may be two shafts. Will be disposed.

It is a side view of the injection molding machine concerning this invention. It is a longitudinal cross-sectional view between the back plate and injection plate of an injection device. It is a figure which shows the side surface (A) of a tie bar, a plane (B), and a cross section (C).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection device 2 Machine stand 3 Clamping device 11 Tie bar 11b Plate part 12 Front plate 13 Rear plate 14 Injection plate 14 'Tie bar insertion hole 21 Strain detector 31 Tie bar 31b Plate part 32 Fixed platen 33 Pressure receiving plate 34 Movable platen 34 'Tie bar insertion hole 37 Toggle mechanism

Claims (3)

A front plate having an injection heating cylinder attached thereto and a rear plate having an electric injection driving means attached thereto connected by a tie bar, and an injection plate provided between the plates connected to the injection driving means so as to be movable forward and backward, and a fixed platen And a pressure receiving plate on which electric mold clamping drive means is attached by means of a tie bar, and an injection molding machine provided with a mold clamping device provided between the two plates so that the movable plate is connected to the mold clamping drive means and can be moved forward and backward.
The tie bar of the injection device and / or the mold clamping device is a steel bar formed in a plate-like portion in which a side surface excluding both ends of a round bar is formed into a long flat surface and a cross-sectional area is partially reduced. An electric injection molding machine comprising a strain detector attached to a portion.   2. The plate-like portion is formed to be long by being shifted to one end portion of a round bar, and a tie bar is disposed with the plate-like portion side set as the rear plate or the pressure platen side. Electric injection molding machine.   The injection plate and the movable platen are provided with an insertion hole for the tie bar, and the diameter of the insertion hole is formed larger than the tie bar diameter so that the load of the injection plate or the movable plate does not interfere with the tie bar. The electric injection molding machine according to claim 1.

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