JP3754432B2 - Electric injection device - Google Patents

Description

  The present invention relates to an injection apparatus for an injection molding apparatus that injects a molding material such as rubber in an injection chamber from a nozzle into a molding die by a forward movement of the plunger, and more particularly to an electric injection apparatus that moves a plunger forward and backward by an electric motor. .

Conventionally, an injection molding apparatus has been widely used as a molding apparatus for rubber molded products and the like.
As an injection device in this injection molding device, a hydraulic drive type device has been used in which the plunger is driven forward by hydraulic pressure.

  In this hydraulic drive type injection device, the plunger is moved forward by hydraulic drive, and the injection material such as rubber filled in the injection chamber of the cylinder is vigorously injected into the cavity of the mold from the nozzle at the tip of the cylinder. .

  However, in the case of a hydraulic drive type injection device that moves the plunger forward by hydraulic drive, there is a problem that the hydraulic fluid leaks or the splash of the hydraulic fluid flies around and contaminates the surrounding environment, and it is also a loss in terms of energy efficiency. There are problems such as.

Therefore, in recent years, an electric injection device that moves the plunger back and forth with an electric motor has been used.
In the case of the electric injection device, there is an advantage that the hydraulic oil does not leak and splashes do not fly around, and there is little energy loss when generating and transmitting the driving force.

In this electric injection device, the plunger is normally moved back and forth using a ball screw mechanism.
At that time, usually, the ball screw shaft is rotatably supported by a bearing on the outer peripheral side with a fixed platen, while a ball nut screwed to the ball screw shaft is attached to the movable platen, and screw feed action is performed by rotating the ball screw shaft. The movable platen is moved forward and backward, and an injection material such as rubber filled in the injection chamber is injected from the nozzle toward the molding die by a plunger fixed to the movable platen during the forward movement.

FIG. 4 shows a specific example thereof.
In the figure, reference numeral 200 denotes a fixed platen, 202 denotes a movable platen fixed with a plunger 204, 206 denotes a ball screw shaft, and 208 denotes a ball nut screwed thereto.
The ball screw shaft 206 penetrates the fixed platen 200 in the axial direction, and is supported by the fixed platen 200 on the outer peripheral side so as to be rotatable by the bearing 210 and not movable in the axial direction.

  An end portion of the ball screw shaft 206 protruding upward in the figure from the fixed platen 200 is operated by an electric motor (not shown) via a driven pulley 212 fixed thereto, a belt 214 wound around the pulley, and the like. The ball screw shaft 206 is rotationally driven by such an electric motor.

  On the other hand, the ball nut 208 screwed to the ball screw shaft 206 is attached to the movable platen 202, and the movable platen 202 advances and retreats in the vertical direction in the drawing by the screw feeding action to the ball nut 208 by the rotation of the ball screw shaft 206. It can be moved.

Here, the ball nut 208 and the movable platen 202 are provided to prevent the lower end portion of the ball screw shaft 206 in the drawing and the movable platen 202 from coming into contact with each other when the ball nut 208 moves backward, that is, moves upward in the drawing. In order to ensure a moving stroke of the ball nut 208 and the movable platen 202, a cylindrical spacer member 216 is interposed between the ball nut 208 and the movable platen 202.
An escape portion 218 for allowing the ball screw shaft 206 to escape during retraction is secured inside the spacer member 216 as a space.

  However, when the movable platen 202 is moved forward and backward through the ball screw mechanism as described above, if the ball screw shaft 206 is supported by the bearing 210 so as to be rotatable and immovable in the axial direction, the ball screw shaft 206 is effective. The length of the screw is limited to a portion protruding downward from the fixed plate 200, strictly speaking, the bearing 210 in the drawing, and in addition, the ball nut 208 is movable via the spacer member 216 for forming the relief portion 218 as described above. Since it is necessary to connect the board 202, the overall length of the injection device in the axial direction (vertical direction in the figure) becomes long, resulting in a problem that the injection device becomes large.

  On the other hand, as shown in FIG. 5, the ball nut 208 itself is supported by the fixed platen 200 so as to be rotatable by the bearing 210 and immovable in the axial direction, and the ball nut 208 is driven to rotate. It is conceivable that the ball screw shaft 206 screwed to this is moved forward and backward in the axial direction by a screw feed action, and the movable platen 202 attached with the ball screw shaft 206 is moved forward and backward in the figure. Yes.

  For example, in Patent Document 1 below, a ball nut is supported by a fixed platen so as to be rotatable by a bearing and not movable in the axial direction, and the ball nut is rotated to drive the ball screw shaft. It is disclosed that it is made to move forward and backward in the axial direction integrally with a fixed movable platen.

  In the case of the injection apparatus shown in FIG. 5, when the movable platen 202 is retracted, the ball screw shaft 206 can be protruded upward in the drawing through the fixed platen 200, that is, escaped. Since the member 216 can be dispensed with, the overall length of the injection device in the vertical direction in the drawing can be shortened.

  However, on the other hand, in the case of the injection device shown in FIG. 5, the ball nut 208 itself is rotatably supported by the bearing 210 by the fixed platen 200, so that the size in the direction perpendicular to the axis inevitably increases. Arise.

  In particular, in the case of a high-load ball screw mechanism that has come to be adopted in recent years, a return pipe 220 for returning the ball is provided in a form protruding from the outer surface of the ball nut 208 as shown in FIG. Therefore, the dimension in the direction perpendicular to the axis of the stationary platen 200 is further increased.

  In order for the return pipe 220 to receive (support) the ball nut 208 protruding outside by the bearing 210, the ball nut 208 must be attached via a separate attachment member 222 for forming the relief portion 224. In addition, the protrusion of the return pipe 220 and the mounting member 222 cause a problem that the size of the stationary platen 200, and hence the injection device, in the direction perpendicular to the axis becomes larger.

JP-A-5-84792

  In view of such circumstances, the present invention has been made with the object of providing an electric injection device that can shorten the overall length of the plunger in the forward / backward movement direction and can also reduce the size in the direction perpendicular to the axis. It is a thing.

  Thus, according to the first aspect of the present invention, in a state where a hollow shaft having a hollow portion into which the ball screw shaft is inserted is centrally rotated with respect to the ball nut screwed to the ball screw shaft. The hollow shaft is connected in the axial direction, and the hollow shaft is rotatably supported by a bearing on the outer peripheral side. The hollow shaft and the ball nut are operatively connected to an electric motor. The movable plate fixed with the plunger is moved forward and backward by being rotated by the electric motor, and the injection material in the injection chamber is injected from the nozzle toward the mold during the advancement. To do.

  According to a second aspect of the present invention, in the first aspect, the hollow shaft is attached to the stationary platen by the bearing, and the ball screw shaft is attached to the movable platen.

  A third aspect of the present invention is characterized in that in any one of the first and second aspects, the hollow shaft and the ball nut are separated and are detachably fastened by a fastener. .

Effects and effects of the invention

  As described above, according to the present invention, the hollow shaft is continuously connected to the ball nut in the axial direction, and the hollow shaft is rotatably supported by the bearing. By rotating and driving the side with an electric motor, the movable plate fixed with the plunger is moved forward and backward by a screw feeding action between the ball nut and the ball screw shaft. Since the ball screw shaft can be inserted into the hollow portion of the hollow shaft that is rotatably supported by the bearing at the time of retreating, that is, the ball screw shaft can be released into the hollow portion. The total length of the plunger and the movable plate in the advance / retreat direction can be effectively shortened.

On the other hand, in the present invention, a hollow shaft is connected to the ball nut in the axial direction, and the hollow shaft is rotatably supported by a bearing. Even when the radial direction of the ball nut, that is, the dimension perpendicular to the axis is increased by the return pipe, the axial dimension of the support portion by the bearing, that is, the size perpendicular to the axis is increased accordingly. It is possible to avoid problems such as
Therefore, according to the present invention, it is possible to reduce both the axial direction size and the axial perpendicular direction size.

  In the present invention, the hollow shaft can be attached to the stationary platen with a bearing, and the ball screw shaft can be attached to the movable platen (Claim 2).

Further, the hollow shaft and the ball nut can be separated and fastened with a fastener so as to be detachable.
In such a case, even when maintenance inside the ball nut is required, it is possible to easily perform maintenance work inside the ball nut by releasing the fastening with the fastener and removing the ball nut from the hollow shaft. It becomes possible.

Next, an embodiment in which the present invention is applied to an injection device for rubber will be described in detail with reference to the drawings.
In FIG. 1, reference numeral 10 denotes an injection apparatus according to this embodiment, which includes an extruder 12 for pre-plasticizing a rubber material.
The extruder 12 has a screw 14 and an electric motor 16 (a driving source other than the electric motor may be used), and the rubber material supplied from the supply port 15 is plasticized by the rotation of the screw 14 and sufficiently Then, the check valve 18 is pushed open and pushed into an injection chamber 22 formed in an injection cylinder 20 described later.

Reference numerals 24 and 26 denote upper and lower fixed plates, respectively.
Reference numeral 30 denotes a movable plate, which is fixed to the lower surface in the figure with a plunger 32 protruding downward.

  The movable platen 30 is guided by the tie rod 28 to move back and forth in the vertical direction in the figure, and when the forward movement moves downward in the figure, the plunger 32 is pushed deeply into the injection chamber 22 to fill the injection chamber 22. The rubber material is vigorously injected from the nozzle 34 into the cavity 38 of the mold 36 and filled.

A ball screw shaft 40 in a ball screw mechanism is attached to the lower surface of the movable plate 30, that is, the upper surface opposite to the surface on which the plunger 32 is fixed, and this ball screw shaft 40 is attached to the movable plate 30. It extends upward from the upper surface in the figure.
Reference numeral 42 denotes a ball nut in the ball screw mechanism. As shown in FIG. 2, the ball nut 42 is screwed onto the ball screw shaft 40 via a ball 43.

In this example, the ball screw mechanism is for a high load load, and a return pipe 46 for returning the ball 43 from one end of the screw to the other end is provided in a state protruding from the ball nut 42.
On the upper side of the ball nut 42 in the drawing, the hollow shaft 44 is fastened in the axial direction by a bolt 47 in a state of rotating integrally with the ball nut 42.

The hollow shaft 44 is a cylindrical member having a hollow portion 48 into which the ball screw shaft 40 is inserted at the center, and is provided in a state of penetrating the fixed platen 24 in the axial direction (vertical direction). A portion penetrating the shaft is rotatably attached to and supported by the fixed platen 24 by a bearing 50 on the outer peripheral side.
The hollow shaft 44 has an upper end protruding above the fixed platen 24, and a driven pulley 52 is fixed to the protruding portion in an integrally rotated state.

  In FIG. 1, reference numeral 54 denotes an electric motor as a drive source for the plunger 32, and a reduction gear 56 is connected to the upper side in the drawing, and a drive shaft 58 protrudes from the reduction gear 56. A drive pulley 60 is fixed to the drive shaft 58.

  A belt 62 is wound between the driving pulley 60 and the driven pulley 52, and the driving force of the electric motor 54 passes through the speed reducer 56, the driving pulley 60, the belt 62, and the driven pulley 52 to the hollow shaft 44. The hollow shaft 44 is rotationally driven by the electric motor 54. That is, the ball nut 42 of the ball screw mechanism provided integrally with the hollow shaft 44 is rotated by the electric motor 54.

Next, the operation of the injection apparatus of this embodiment will be described.
In the injection device 10, as described above, the rubber material is first supplied from the supply port 15 into the cylinder of the extruder 12.
The supplied rubber material is sufficiently plasticized, that is, fluidized by the rotation of the screw 14, and then pushed out and supplied into the injection chamber 22 of the injection cylinder 20 through the check valve 18.

At this time, the plunger 32 is in a state of being moved downward in the figure, and as the rubber material is supplied into the injection chamber 22, back pressure is applied to the rubber material while the supply amount is increased. Move backwards upward.
The backward movement at this time is performed as follows.

  That is, in this example, the upward pressure (retracting direction) of the rubber filled in the injection chamber 22 to the plunger 32 and the torque applied from the electric motor 54 to the ball screw shaft 40 through the hollow shaft 44 and the ball nut 42. As a result, the movable plate 30 is lifted upward together with the plunger 32 in the drawing to move them backward.

  When the set amount of the rubber material is filled in the injection chamber 22 in this way, the extrusion of the rubber material by the extruder 12 and the backward movement of the plunger 32 are stopped.

In this state, the ball nut 42 is then rotated in the opposite direction to that described above, whereby the ball screw shaft 40 is now pushed downward in the figure by a screw feed action.
As a result, the movable platen 30 to which the ball screw shaft 40 is attached moves forward downward, and as a result, the plunger 32 that moves integrally with the movable platen 30 is pushed downward in the figure, and the rubber filled in the injection chamber 22 is filled. Material is injected all at once from the nozzle 34 into the cavity 38 of the molding die 36.

  As described above, according to this example, when the movable platen 30 is retracted, the ball screw shaft 40 is passed through the hollow portion 48 of the hollow shaft 44 that is rotatably supported by the bearing 50 in the drawing. Since it can escape to the upper side, the total length of the injection device 10 in the vertical direction in the drawing, that is, the plunger 32 and the movable platen 30 can be effectively shortened.

In this example, since the hollow shaft 44 is connected to the ball nut 42 in the axial direction and the hollow shaft 44 is rotatably supported by the bearing 50, a ball screw mechanism for a high load load is provided. Even when the return pipe 46 protrudes to the outside of the ball nut 42 and the dimension of the ball nut 42 in the direction perpendicular to the axis increases, the support portion by the bearing 50, that is, the axis perpendicular to the fixed platen 24 is used. The direction size does not increase.
Therefore, according to this example, both the axial direction size and the axial perpendicular direction size in the electric injection device can be reduced.

  Further, since the hollow shaft 44 and the ball nut 42 are separated and fastened with the bolt 47 so as to be detachable, the bolt 47 can be fastened even when maintenance inside the ball nut 42 is required. By unraveling and removing the ball nut 42 from the hollow shaft 44, it becomes possible to easily perform maintenance work inside thereof.

  FIG. 3 shows another embodiment of the present invention. Here, a ball screw shaft 40 is attached to the stationary platen 24, while a hollow shaft 44 is rotatably supported by a bearing 50 on the movable platen 30 side. The ball nut 42 is fastened to the upper side of the hollow shaft 44 in the drawing with a bolt 47 so as to be integrally rotated, and the ball screw shaft 40 is screwed to the ball nut 42.

  In the embodiment shown in FIG. 3, the driving force from the electric motor 54 is transmitted to the driven pulley 52 fixed to each hollow shaft 44 through the driving shaft 58, the driving pulley 60, and the belt 62. Then, the ball nut 42 rotates and the movable platen 30 moves forward and backward in the vertical direction in the figure with respect to the fixed position of the ball screw shaft 40, that is, the fixed platen 24, by the screw feed action (the electric motor provided movably at this time). Also move together).

Although the embodiment of the present invention has been described in detail above, this is merely an example.
For example, the present invention can be applied to various other forms of injection devices other than the above examples, and the plunger may be a screw type depending on the form. The invention can be configured in various forms without departing from the spirit of the invention.

It is a figure which shows the electrically driven injection apparatus of one Embodiment of this invention. It is a figure which expands and shows the principal part of the electric injection device of the embodiment. It is a figure which shows the principal part of the electrically driven injection apparatus of other embodiment of this invention. It is a figure which shows the principal part of the conventional example of an electrically driven injection apparatus. It is a figure which shows the principal part of the electric injection device of the form different from the conventional FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric injection device 22 Injection chamber 24 Fixed board 30 Movable board 32 Plunger 34 Nozzle 36 Mold 40 Ball screw shaft 42 Ball nut 44 Hollow shaft 47 Bolt 48 Hollow part 50 Bearing 54 Electric motor

Claims (3)

  A hollow shaft having a hollow portion into which the ball screw shaft is inserted at the center portion of the ball nut that is screwed onto the ball screw shaft is connected in the axial direction while rotating integrally with the ball nut. The shaft is rotatably supported by a bearing on the outer peripheral side, the hollow shaft and the ball nut side are operatively connected to an electric motor, and the hollow shaft and the ball nut are rotated by the electric motor, An electric injection apparatus characterized in that a movable plate on which a plunger is fixed is moved forward and backward, and an injection material in an injection chamber is injected from a nozzle toward a mold during advancement.   2. The electric injection apparatus according to claim 1, wherein the hollow shaft is attached to a stationary platen by the bearing, and the ball screw shaft is attached to the movable platen.   The electric injection device according to claim 1, wherein the hollow shaft and the ball nut are separated from each other and are fastened so as to be detachable by a fastener.

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