Automatic Die Exchanger for Injection Molding Machine

The present invention relates to an automatic die exchanger for an injection molding machine, which can automatically exchange a die of an injection molding machine with a simple structure and a simple operation.

When an injection molding system for plastic molding is systematized for the purpose of automatization and energy savings, the control system of the injection molding machine must be improved and, at the same time, a total system of the injection molding machine and peripheral equipment must be systematized. As one of the methods for this purpose, automatic die exchange is proposed. However, a conventional automatic die exchanger consists of a die stock section using an automated warehouse or the like, a convey unit utilizing an unmanned convey vehicle and an overhead traveling crane, and a control section for controlling the die stock section and the convey unit. In exchanging a die, after the die is removed from an injection molding machine, it is conveyed to the die stock section by the convey unit and is stored therein. Thereafter another die is fetched from the die stock section, is conveyed to the injection molding machine by the convey unit, and is mounted thereon. Since systems of this type tend to be of a large scale and require a high cost, they are not widely used.

It is an object of the present invention to provide an automatic die exchanger in which the above conventional drawbacks are eliminated and which can automatically exchange a die of an injection molding machine with a simple structure and a simple operation.

In order to achieve the above object, in an automatic die exchanger for an injection molding machine of the present invention, a plurality of die placing sections are provided on a rotational table at angular intervals, a travel member capable of travelling between a die placing section and a die mounting section of the injection molding machine is provided, and a convey means is provided on the travel member. The convey means is engaged with a die, feeds the die from the die placing section to the die mounting section, and conveys the die from the die mounting section to the die placing section.

In this manner, in the automatic die exchanger of the present invention, a die which is selected by rotating the rotational table is brought to oppose the die mounting section of the injection molding machine, the convey means which is integrally movable with the travel member is engaged with the die, and the die is thus fed to or removed from the injection molding machine. Therefore, die exchange can be automatically performed without a need for a large-scale apparatus for die exchange and with a simple operation.

FIG. 1 is a front view of an automatic die exchanger of an injection molding machine according to an embodiment of the present invention;

FIG. 2 is a plan view of the die exchanger shown in FIG. 1 from which a die convey section is removed;

FIG. 3 is a partially sectional right-side view of the die exchanger shown in FIG. 1; and

FIG. 4 is a plan view of the die convey section shown in FIG. 1.

FIGS. 1 to 4 show an automatic die exchanger of an injection molding machine according to an embodiment of the present invention. The automatic die exchanger is provided behind the injection molding machine (only a die clamping section thereof is shown by 5a' as a die mounting section). In the automatic die exchanger, reference numeral 1 denotes a rotational table extending in a horizontal direction; 2, a rotating shaft (refer to FIG. 3) having an upper end fitted in a vertical central hole of the rotational table 1 and supporting the table 1 to be capable of rotating therewith; and 3, a machine frame obtained by assembling a plurality of frames in a substantially cubic manner. The rotating shaft 2 is supported by a support frame 3a fixed on the central portion of the bottom frame of the machine frame 3. A sprocket S1 fixed to the lower end of the shaft 2 is coupled through a chain 4 to a sprocket S2 fixed to the output shaft of a servo motor M1 fixed on the bottom frame of the machine frame 3. Thus, the rotating shaft 2 and the rotational table 1, integrally rotatable therewith are driven by the motor M1.

Die placing sections A to D for placing four dies 5a to 5d, respectively, are placed on the upper surface of the rotational table 1 at equal angular intervals of about 90.degree., as shown in FIG. 2. Pairs of roller arrays Ra to Rd are provided on the two side ends of the die placing sections A to D, respectively. The dies 5a to 5d are slidably placed on the roller arrays Ra to Rd, respectively. Solenoid-type or hydraulic cylinder-type actuators 7a to 7d (hydraulic cylinder-type actuators in this embodiment) for driving stoppers 6a to 6d, which prevent movement of the dies 5a to 5d, are arranged at outer peripheral edge portions of the rotating table 1 to be adjacent to outer edges of the die placing sections A to D, respectively. The stoppers 6a to 6d are disposed to project in and withdraw from a convey path for the dies 5a to 5d, which extends between the die placing sections A to D and a die clamping section 5a' of the injection molding machine.

Rollers 8a to 8d are, respectively, provided on one side of the convey path, and a roller 9 operable to cooperate with the rollers 8a to 8d is provided on the other side of the convey path, so as to guide the dies 5a to 5d to the die molding section 5a' smoothly from the die placing sections A to D. Other rollers (some are indicated by 9') are also provided on the convey path side close to the injection molding machine. More specifically, the roller 9 is arranged on the convey path defining section of the machine frame 3, i.e., on the upper surface of a horizontal outer frame opposing the injection molding machine and matched with the rotational table 1 in height. A pair of guide rods 10a and 10b extend between the vertical outer frames of the machine frame 3 at locations above the rotational table 1 horizontally and parallel to each other, as shown in FIGS. 1, 3, and 4. Two slide sections integrally project from the lower surface of the main portion of the travel member 11 arranged on the guide rods 10a and 10b and are separated from each other. The slide sections are slidably fitted on the rods 10a and 10b, respectively. Thus, the travel member 11 is guided by the guide rods 10a and 10b to move to the right and left in FIGS. 1 and 4. One end of a convey means 14 is pivotally fixed on the travel member 11 side close to the die molding section 5a' by a pin P1. A bracket projecting from the one end of the convey means 14 is fixed on the distal end of a piston rod 13 of a hydraulic cylinder 12 fixed on the travel member 11. When the cylinder 12 is actuated, the convey means 14 is pivoted about the pin P1 in a vertical plane.

The convey means 14 has a die receiving means 15 at its other end. The means 15 is pivotally supported by a pin P2 and is pivoted about the pin P2 by a hydraulic cylinder 16 fixed on the convey means 14. Upon pivot movement of the means 15, an engaging portion 15a of the means 15 is engaged with or disengaged from the corresponding engaging portions (an engaging portion of die 5a is shown as 19a in FIG. 4) provided on the dies 5a to 5d. A servo motor M2 is fixed on one end of one upper horizontal frame of the machine frame 3. A sprocket S3 is fixed on the drive shaft of the servo motor M2 A sprocket S4 is pivotally fixed on the bracket fixed on the other upper horizontal frame of the machine frame 3. A chain 17 extends between the sprockets S3 and S4. The main portion of the travel member 11 is fixed on the chain 17 through a fixing member 18.

The automatic die exchanger of the above arrangement is arranged behind the injection molding machine such that the travel direction of the travel member 11 opposes the die mounting section of the injection molding machine, i.e., the die clamping section 5a'.

The operation of the automatic die exchanger of this embodiment will be described.

First, one of the dies 5a to 5d to be mounted on the injection molding machine is selected. The servo motor M1 is driven to rotate the rotational table 1 until the selected die reaches a portion (the position at which the roller 9 is provided) opposing the die clamping section 5a' of the injection molding machine. The dies 5a to 5d are placed around the rotating shaft 2 on the rotational table 1 at angular intervals of 90.degree.. Therefore, when the rotational table 1 is rotated through 90.degree. to cause one of the dies 5a to 5d to oppose the die clamping section 5a' of the injection molding machine, the dies 5a to 5d are positioned at substantially the same positions. Assume that the die 5a is selected. Then, when the first hydraulic cylinder 12 is actuated to extend the piston rod 13, the convey means 14 is pivoted counterclockwise about the pin P1 to a position indicated by a solid line in FIG. 1. Subsequently, the piston rod of the second hydraulic cylinder 16 is extended to pivot the die receiving means 15 counterclockwise in FIG. 1 about the pin P2, and the engaging portion 15a of the means 15 is engaged with the engaging portion 19a of the die 5a, thus receiving the die 5a, as indicated by a solid line in FIG. 1. The actuator 7a is then actuated to withdraw the stopper 6a from the convey path The servo motor M2 drives the sprockets S3 and S4 and the chain 17, so as to move the travel member 1, which is coupled to the rotating chain 17 through the fixing member 18, to the left in FIGS. 1 and 4 along the guide rods 10a and 10b. As the travel member 11 moves, the convey means 14 movable integrally therewith also moves, and the die receiving means 15 of the means 14 urges against the die 5a. The die 5a moves on the roller array Ra, onto the roller 8a and the roller 9 on the machine frame 3, and then onto the rollers 9' of the machine frame 3 side close to the injection molding machine, so as to be conveyed to a position aligned with the die clamping section 5a' of the injection molding machine indicated by a long and two short dashed line in FIGS. 1 and 4.

Subsequently, the piston rod of the second hydraulic cylinder 16 is retracted to pivot the die receiving means 15 clockwise in FIG. 1 about the pin P2 in order to disengage the die 5a from the die receiving means 15. The servo motor M2 is then driven in the reverse direction to move the travel member 11 and the convey means 14 backward (to the right in FIGS. 1 and 4) to the travel start position. At the same time, the piston rod 13 of the hydraulic cylinder 12 is retracted to pivot the convey means 14 clockwise about the pin P1. The servo motor M2 is then stopped, and the stopper 6a is caused to project at the die lock position by the actuator 7a, thereby restoring the automatic die exchanger to the initial state. The die 5a which is conveyed to the die clamping section 5a' of the injection molding machine in this manner is mounted on the stationary and movable bases constituting the die clamping section 5a' of the injection molding machine, and the die mounting operation is completed.

When the die 5a is removed from the injection molding machine, the empty one of the placing sections A to D (A, in this embodiment) on the rotational table 1 is caused to oppose the injection molding machine. The actuator 7a is actuated to withdraw the stopper 6a again. Then, the servo motor M2 is driven to move the travel member 11 forward to the travel end position (to the left in FIGS. 1 and 4), and is stopped Subsequently, the piston rod 13 of the first hydraulic cylinder 12 is extended, and the piston rod of the second hydraulic cylinder 16 is extended so as to engage the engaging portion 15a of the die receiving means 15 with the engaging portion 19a of the die 5a which is removed from the die clamping section 5a' in advance. Thereafter, the servo motor M2 is driven in the reverse direction to remove the die 5a from the injection molding machine. The die 5a is placed on the rollers 9 and 8a and the roller array Ra and is moved to the right in FIG. 1. When the die 5a is completely placed on the die placing section A on the rotational table 1, the servo motor M2 is stopped. The stopper 6a is caused to project in the convey path to fix the die 5a the piston rod of the second hydraulic cylinder 16 is retracted to disengage the die 5a from the die receiving means 15, the piston rod 13 of the first hydraulic cylinder 12 is retracted to pivot the convey means 14 clockwise in FIG. 1 about the pin P1 to a position not interfering with the dies 5a to 5d, and the removal operation of the die 5a is completed.

The above die exchange operation is repeated as required to selectively mount a desired die in the injection molding machine.

In the above embodiment, four die placing sections A to D are provided on the rotational table 1. However, the rotational table 1 can be increased in size so that it can place more die placing sections thereon. In this case, die placing sections of the same shape are preferably provided at equal angular intervals. In the above embodiment, the servo motors M1 and M2 are used as the drive means for the rotational table 1 and the travel member 11. However, a general-purpose motor can be used instead, and the positions of the rotational table 1 and the travel member 11 can be detected by limit switches to control the motor. Furthermore, the rotational table 1 can be driven manually instead of by a motor. The convey means 14 is pivotally supported by the travel member 11, and the convey means 14 is inserted between the dies and the die is conveyed. However, a plunger of a solenoid-type actuator or a piston rod of a hydraulic cylinder can vertically project from the travel member 11, and the die and the plunger or the piston rod can be manually coupled or separated through an appropriate convey auxiliary member, thereby feeding the die in or out.