JP2014226891A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine which can improve the abrasion (galling) of a screw.SOLUTION: An injection molding machine 10 includes a cylinder 41 which has a molding material supply port 42 at a rear part thereof, and a screw 43 which rotates in the cylinder 41 to send forward a molding material supplied from the molding material supply port 42. The screw 43 includes a supply part P1, a compression part P2, and a measuring part P3 in this order from the vicinity of the molding material supply port 42 to a front side. In at least a part of the compression part P2, a plurality of flights 49-1, 49-2 are arranged symmetrically about a center line of the screw 43 so that a plurality of solid beds 51 are formed symmetrically about the center line of the screw 43 when viewed in cross section.

Description

  The present invention relates to an injection molding machine.

  The injection molding machine has an injection device that fills a cavity space of a mold device with a liquid phase molding material. The injection device includes a cylinder having a molding material supply port at the rear portion thereof, and a screw that is rotatably and reciprocally disposed in the cylinder (see, for example, Patent Document 1). Along with the rotation of the screw, the solid-phase molding material is fed forward along a spiral groove formed in the screw and gradually melted by the heat of the heater. As the liquid phase molding material is fed to the front of the screw and accumulated in the front of the cylinder, the screw moves backward.

International Publication No. 2007/105646

  In some cases, the solid-phase molding material in the cylinder presses the screw against the cylinder, and frictional wear (galling) may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection molding machine that can improve screw wear (galling).

In order to solve the above problems, according to one aspect of the present invention,
A cylinder having a molding material supply port at the rear;
A screw that feeds the molding material supplied from the molding material supply port forward by rotating in the cylinder;
The screw has a supply part, a compression part, and a measuring part sequentially from the vicinity of the molding material supply port toward the front,
At least in part of the compression section, in a cross-sectional view, the plurality of flights are arranged symmetrically about the screw center line so that the solid beds are formed symmetrically about the screw center line. An injection molding machine is provided.

  According to one aspect of the present invention, an injection molding machine that can improve screw wear (galling) is provided.

It is a figure which shows the injection apparatus of the injection molding machine by one Embodiment of this invention. It is sectional drawing along the II-II line of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof will be omitted. Moreover, the screw moving direction (left direction in FIG. 1) in the filling step is assumed to be the front, and the screw moving direction (right direction in FIG. 1) in the weighing step is assumed to be the rear.

  FIG. 1 is a view showing an injection molding machine according to an embodiment of the present invention. In FIG. 1, the illustration of the molding material is omitted for easy viewing of the drawing. FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  The injection molding machine includes an injection device 40 that fills the cavity space CV of the mold device 30 with a liquid phase molding material. The mold apparatus 30 includes, for example, a fixed mold 32 and a movable mold 33, and a cavity space CV is formed between the fixed mold 32 and the movable mold 33. The liquid phase molding material filled in the cavity space CV is solidified to obtain a molded product.

  The injection device 40 drives, for example, a cylinder 41 having a molding material supply port 42 at the rear, a screw 43 that feeds the molding material supplied from the molding material supply port 42 by rotating in the cylinder 41, and the screw 43. The drive part 45 which has. The screw 43 is disposed in the cylinder 41 so as to be rotatable and to be able to advance and retreat. The drive unit 45 may be a general one, and includes, for example, a metering motor that rotates the screw 43 and an injection motor that moves the screw 43 back and forth.

  The molding material supply port 42 is an opening that supplies a molding material (for example, resin pellets) into the cylinder 41. A hopper is connected to the molding material supply port 42, and the molding material is supplied into the cylinder 41 from the hopper via the molding material supply port 42.

  In the present embodiment, a hopper is used as the material supply unit that supplies the molding material to the molding material supply port 42, but a feeder capable of adjusting the supply speed may be used. The feeder includes, for example, a feed cylinder and a feed screw that feeds a molding material by rotating in the feed cylinder. The supply speed of the molding material can be adjusted by the rotational speed of the feed screw.

  As the screw 43 rotates, the solid-phase molding material is fed forward along the spiral groove formed in the screw 43 and is gradually melted by the heat of the heaters H1 to H4. The heaters H <b> 1 to H <b> 4 are provided so as to surround the cylinder 41 and heat the molding material in the cylinder 41 by heating the cylinder 41. As the liquid phase molding material is fed to the front of the screw 43 and accumulated in the front part of the cylinder 41, the screw 43 is retracted.

  Next, the operation of the injection molding machine having the above configuration will be described. The operation of the injection molding machine is controlled by a controller composed of a macro computer or the like.

  In the mold closing process, the movable mold 33 is moved closer to the fixed mold 32. When the movable mold 33 and the fixed mold 32 come into contact with each other, the mold closing is completed. After the mold closing is completed, the mold clamping process is started.

  In the mold clamping process, a mold clamping force is generated between the movable mold 33 and the fixed mold 32. A cavity space CV is formed between the fixed mold 32 and the movable mold 33 in the clamped state. During the mold clamping process, a filling process, a pressure holding process, and a cooling process are performed.

  In the filling step, the injection motor is driven to advance the screw 43 at a set speed, and the liquid phase molding material accumulated in front of the screw 43 is filled into the cavity space CV of the mold apparatus 30. The set speed of the screw 43 may be constant or may be changed according to the screw position or the elapsed time. When the screw 43 moves forward to a predetermined position (so-called V / P switching position), the pressure holding process is started. Note that when the elapsed time from the start of the filling process reaches a predetermined time, the pressure holding process may be started.

  In the pressure holding step, the injection motor is driven to push the screw 43 forward at a set pressure, and the molding material corresponding to the volume shrinkage due to the cooling of the molding material in the cavity space CV is replenished. The set pressure of the screw 43 may be constant or may be changed according to the elapsed time. After the inlet (so-called gate) of the cavity space CV is sealed and the backflow of the molding material from the cavity space CV is prevented, the cooling process is started.

  In the cooling process, the molding material in the cavity space CV is solidified. During the cooling step, a metering step for weighing the molding material for the next molded part may be performed.

  In the metering process, the metering motor is driven to rotate the screw 43 at the set rotational speed, the molding material is fed forward along the spiral groove formed in the screw 43, and is gradually melted by the heat of the heaters H1 to H4. Let As the liquid phase molding material is fed to the front of the screw 43 and accumulated in the front portion of the cylinder 41, the screw 43 is retracted.

  In the measuring step, a predetermined back pressure may be applied to the screw 43 by driving the injection motor in order to limit the rapid retreat of the screw 43. When the screw 43 is retracted to a predetermined position and a predetermined amount of molding material is accumulated in front of the screw 43, the measuring step is finished. The set rotational speed of the screw 43 may be constant or may be changed according to the screw position or the elapsed time.

  The mold opening process is performed after the cooling process. In the mold opening process, the movable mold 33 is separated from the fixed mold 32. After the mold opening is completed, the molded product is ejected from the movable mold 33.

  Next, the screw 43 will be described in detail with reference to FIGS. 1 and 2 again.

  As shown in FIG. 1, the screw 43 includes a shaft portion 47 and a plurality of flights 49-1 and 49-2 provided spirally around the shaft portion 47. A spiral groove is formed along each flight 49-1, 49-2.

  Further, as shown in FIG. 1, the screw 43 is divided into a supply part P1, a compression part P2, and a measuring part P3 from the vicinity of the molding material supply port 42 toward the front. The supply part P1 is a part which receives the solid-state molding material and conveys it forward. The compression part P2 is a part that melts the solid-state molding material while compressing it. The measuring part P3 is a part that measures a fixed amount of the liquid phase molding material. The depth of the groove of the screw 43 is deeper at the supply part P1, shallower at the measuring part P3, and shallower toward the front in the compression part P2.

  In the compression part P2, as shown in FIG. 2, the molding material forms a solid bed 51 and a melt pool 52. The solid bed 51 is a collection of solid-phase molding materials (for example, resin pellets), and the melt pool 52 is a collection of liquid-phase molding materials (for example, molten resin). A solid bed 51 and a melt pool 52 are formed across the flights 49-1 and 49-2. The solid bed 51 and the melt pool 52 are formed in each of the plurality of grooves 44-1 and 44-2. The plurality of grooves 44-1 and 44-2 are formed between the plurality of flights 49-1 and 49-2, respectively.

  By the way, in the compression part P2, the depth of each groove | channel 44-1, 44-2 is so shallow that it goes ahead as shown in FIG. 1, and the solid bed 51 is compressed, sending forward. By the reaction, the screw 43 is pushed in the radial direction.

  Therefore, in the compression part P2 of the present embodiment, as shown in FIG. 2, the plurality of flights 49-1 are formed so that the plurality of solid beds 51 are formed symmetrically about the center line of the screw 43 in a cross-sectional view. 49-2 are arranged symmetrically about the center line of the screw 43. Here, symmetry means rotational symmetry. For example, the plurality of solid beds 51 have the same size and are formed around the center line of the screw 43 at equal intervals (for example, 180 ° pitch). Thereby, the force which the some solid bed 51 pushes the screw 43 to radial direction is easy to balance. Therefore, the force which presses the screw 43 against the cylinder 41 is reduced, and wear (galling) of the screw 43 can be improved.

  In the present embodiment, the plurality of flights 49-1 and 49-2 are formed from the front end to the rear end of the compression portion P2, but may be formed only on a part of the compression portion P2. A plurality of solid beds 51 may be formed symmetrically about the center line of the screw 43 in a cross sectional view at a position where the force pushing the screw 43 in the radial direction is strong.

  Each of the plurality of flights 49-1 and 49-2 may extend at least to the vicinity of the molding material supply port 42 as shown in FIG. Immediately after the molding material is supplied from the molding material supply port 42 into the cylinder 41, the molding material is divided into a plurality of grooves 44-1, 44-2. Since the state of the molding material supplied to each of the grooves 44-1 and 44-2 is substantially the same, the sizes of the plurality of solid beds 51 are easily aligned in a cross-sectional view.

  The plurality of flights 49-1 and 49-2 have the same supply speed of the molding material from the molding material supply port 42 to the plurality of grooves 44-1 and 44-2. In order to make the conveyance speed of the molding material in 44-2 the same, you may form at equal intervals in the front-back direction.

  Each of the flights 49-1 and 49-2 may extend at least to the vicinity of the molding material supply port 42 when the position of the screw 43 is in the forward limit position, and extend to the rear of the molding material supply port 42. Also good.

  For example, one flight 49-2 may be interrupted at the boundary between the compression unit P2 and the measurement unit P3. In the measuring part P3, most of the molding material is melted, and there is almost no solid-phase molding material that can push the screw 43 in the radial direction. By reducing the number of flights, the passage of the molding material is widened, and the conveying capacity of the measuring unit P3 is improved. In the measuring part P3, a spiral groove 44-3 is formed along the remaining flight 49-1, and the molding material is fed forward along the groove 44-3.

  In the present embodiment, one flight 49-2 is interrupted at the boundary between the compression unit P2 and the measurement unit P3, but may be interrupted in the middle of the compression unit P2 or in the measurement unit P3. . In any case, since one flight 49-2 does not extend to the front end of the measuring unit P3, the conveyance capability of the measuring unit P3 is improved.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments and the like, and various modifications and substitutions may be made within the scope of the present invention described in the claims. Is possible.

  For example, the injection device 40 of the above embodiment is a screw in-line type, but may be a screw / prepa type. In the screw / prep plastic type, the molding material melted in the plasticizing cylinder is supplied to the injection cylinder, and the molding material is injected into the mold apparatus 30 from the injection cylinder. Since the plasticizing cylinder and the injection cylinder are provided separately, the screw disposed in the plasticizing cylinder can be driven to rotate in the filling process or the pressure holding process.

  Moreover, although the screw 43 of the said embodiment has two flights 49-1 and 49-2, it may have three or more flights, and at least a part of the compression part P2 has three or more solids. The bed 51 may be formed symmetrically about the center line of the screw 43. When the screw 43 has three or more flights, at least one flight is interrupted at the boundary between the compression unit P2 and the weighing unit P3, in the middle of the compression unit P2, or in the middle of the measurement unit P3. If it does not extend to the front end, the conveyance capability of the weighing unit P3 is improved.

40 Injection device 41 Cylinder 42 Molding material supply port 43 Screw 44-1, 44-2 Groove 45 Drive unit 49-1, 49-2 Flight 51 Solid bed 52 Melt pool P1 Supply unit P2 Compression unit P3 Metering unit

Claims (3)

A cylinder having a molding material supply port at the rear;
A screw that feeds the molding material supplied from the molding material supply port forward by rotating in the cylinder;
The screw has a supply part, a compression part, and a measuring part sequentially from the vicinity of the molding material supply port toward the front,
At least in part of the compression section, in a cross-sectional view, the plurality of flights are arranged symmetrically about the screw center line so that the solid beds are formed symmetrically about the screw center line. An injection molding machine is installed.   The injection molding machine according to claim 1, wherein each of the plurality of flights extends at least to the vicinity of the molding material supply port.   The injection molding machine according to claim 1, wherein at least one of the plurality of flights is interrupted at a boundary between the compression unit and the measurement unit, in the middle of the compression unit, or in the middle of the measurement unit.

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