JP2973881B2 - 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 injection molding machine for performing injection molding by moving a screw back and forth in a cylinder.

[0002]

2. Description of the Related Art Among injection molding machines which perform injection molding by moving a screw back and forth in a cylinder, an electric type in which a screw is moved forward and backward by an electric motor is disclosed in, for example,
This injection molding machine has a nut fixed to a holding member for rotatably holding a screw, and a screw shaft screwed to the nut is rotated by a motor to remove the nut. The screw is moved forward and backward together with the holding member. Japanese Patent Application Laid-Open No. Sho 61-177221 discloses that a screw is rotated and moved forward and backward by fixing a nut to a screw, rotating a screw shaft screwed to the nut with a motor and rotating the screw with a motor. An injection molding machine is disclosed.

[0003]

The injection molding machine described above is
In each case, the screw is moved forward and backward by using a screw mechanism consisting of a screw shaft and a nut, and the relative rotation of the screw shaft and the nut is considerably high. Lubrication of the shaft and nut is essential, and grease is generally applied to the screw shaft. However, in any of these injection molding machines, the screw shaft rotates at a high speed, and the grease on the screw shaft surface is scattered due to centrifugal force, and the lubricant runs out, and the life of the screw mechanism is extremely short. There was a risk of becoming. Accordingly, an object of the present invention is to provide an injection molding machine capable of preventing the lubricant from being scattered, thereby preventing the life of the screw mechanism from being extremely shortened.

[0004]

The injection molding machine of the present invention comprises:
Injection molding is performed by moving a screw back and forth in a cylinder, and a holding member that rotatably holds the screw, a plurality of mutually parallel screw shafts fixed to the holding member, And a nut screwed to the screw shaft and driven to rotate by a motor. Thus, the screw shaft fixed to the holding member is moved forward and backward by rotating the nut screwed to the screw shaft by the motor, and the screw is moved forward and backward together with the holding member. Therefore, since the screw shaft is non-rotating, the lubricant does not scatter. In addition, since the rotation of the holding member is restricted by the plurality of screw shafts, there is no need to provide a rotation restricting means for restricting the rotation of the holding member only for the rotation restriction.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an injection molding machine according to the present invention will be described below with reference to FIG. In FIG.
Reference numeral 1 denotes a cylinder. The cylinder 11 has a substantially cylindrical heating tube portion 13 in which a resin serving as an injection material is placed and a nozzle portion 12 for injecting the resin is formed on the distal end side. The two support portions 1 extending perpendicularly to the heating tube portion 13 in opposite directions from the base end side of the portion 13.
4,14. Support shafts 15, 15 parallel to the heating cylinder 13 are fixed to the ends of the extending ends of the support portions 14, 14 on the side opposite to the heating cylinder 13. The support portions 14, 1 of these support shafts 15, 15
The end opposite to 4 is fixed to a base 16 that is substantially parallel to the supports 14.

The base 16 has a plurality (two in the illustrated example) of holes 1 penetrating along an axis parallel to the heating cylinder 13.
A substantially cylindrical bottomed rotating member 19, 19 is coaxially and positionally fixed and rotatably supported in each of the holes 18, 18 with an opening disposed on the cylinder 11 side. Have been. These rotating members 19, 19
On the bottom side, the same wheels 20, 20 are fixed coaxially at positions outside the base portion 16, respectively.
On the opening side, the same ball nuts (nuts) 22 are coaxially fixed at positions outside the base portion 16. A servomotor (motor) 24 is attached to the side of the base 16, and a wheel 26 fixed to a rotating shaft 25 of the servomotor 24 and the two wheels 20, 20 have one timing. A belt 27 is wound. Then, by the rotation of the servo motor 24, the two rotating members 20, 20 rotate in the same direction at the same rotation speed.

The same ball screw shafts (screw shafts) 29, 29 are screwed into the two ball nuts 22, 22, respectively. The part can be inserted with a gap. The other end sides of both ball screw shafts 29 are fixed to both end portions of the holding member 30. The holding member 30, which is supported by the base 16 via the ball screw shafts 29, 29, etc., has two ball screw shafts 29, 29
The hole 31 parallel to the cylinder and coaxial with the heating cylinder 13 is
One side is formed with a screw 3
The base end of the screw 3 is rotatably supported coaxially and fixed in position, and the blade 34 on the tip side of the screw 33 is inserted into the heating cylinder 13. A wheel 35 is coaxially fixed to an intermediate portion of the screw 33, and a driving force of a motor (not shown) is transmitted to the wheel 35 via a timing belt (not shown).

In the injection molding machine having such a configuration, the rotation members 19, 19 and the ball nuts 22, 22 are integrally rotated by the one-way rotation of the servo motor 24, and are screwed to the ball nuts 22, 22, and the holding member is rotated. Non-rotating ball screw shafts 29, 29 fixed to 30
The screw 33 retreats inside the heating cylinder 13 by moving on the rotation members 19, 19 toward the bottom of the rotation members 19, 19.
Simultaneously with the retraction, the screw 33 rotates by the driving force of a motor (not shown) to feed the resin plasticized between the inside of the heating cylinder 13 and the tip of the blade 34 of the screw 33. When a predetermined amount of resin is filled between the inside of the heating cylinder portion 13 and the tip of the blade portion 34 of the screw 33, the rotating members 19, 19 and Ball nut 22,2
The screw 33 moves forward by the ball screw shafts 29, 29 moving on the ball nuts 22, 22 by the integral rotation of 2, and the resin is injected from the nozzle portion 12 into the cavity of the mold (not shown).

According to the injection molding machine described above, the ball screw shafts 29 fixed to the holding member 30 are driven forward and backward by rotating the ball nuts 22, 22 screwed thereto with the servo motor 24. In order to move the screw 33 forward and backward together with the holding member 30, the ball screw shaft 2
9 and 29 are non-rotating, so that the ball screw shaft 2
Lubricant applied to 9, 29 does not scatter due to centrifugal force. Therefore, it is possible to prevent the life of the screw mechanism including the ball screw shafts 29, 29 and the ball nuts 22, 22 from being extremely shortened.

Further, since a plurality of (two in the illustrated example) ball screw shafts 29 and 29 are fixed parallel to the holding member 30 to restrict the rotation of the holding member 30, the rotation of the holding member 30 is restricted. It is not necessary to provide a rotation regulating means for regulating only the rotation. Therefore, an unnecessary structure can be eliminated and the structure can be simplified.

[0011]

As described above in detail, according to the injection molding machine of the present invention, the screw shaft fixed to the holding member is moved forward and backward by rotating the nut screwed to the screw shaft by the motor. The screw is moved forward and backward together with the holding member. Therefore, since the screw shaft is non-rotating, the lubricant does not scatter. Therefore, it is possible to prevent the life of the screw mechanism including the screw shaft and the nut from being extremely shortened. In addition, since the rotation of the holding member is restricted by the plurality of screw shafts, there is no need to provide a rotation restricting means for restricting the rotation of the holding member only for the rotation restriction. Therefore, an unnecessary structure can be eliminated and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a plan view, partially in section, showing one embodiment of an injection molding apparatus of the present invention.

[Explanation of symbols]

 11 Cylinder 22 Ball Nut (Nut) 24 Servomotor (Motor) 29 Ball Screw Shaft (Screw Shaft) 30 Holding Member 33 Screw

Claims (1)

(57) [Claims] 1. An injection molding machine for performing injection molding by moving a screw back and forth in a cylinder, comprising: a holding member for rotatably holding the screw; and a plurality of mutually parallel fixing members fixed to the holding member. An injection molding machine comprising: a screw shaft; and a nut screwed to each screw shaft and driven to rotate by a motor.