INJECTION MOLDING SYSTEM

An injection molding system includes: an injection molding machine; a collaborative robot installed outside or inside the injection molding machine; and a control unit that controls the collaborative robot. Before the injection molding machine is brought into operation, the control unit operates the collaborative robot at least in a space inside the injection molding machine where molds are installed, and transmits an operation disable signal to the injection molding machine when contact between an object and the collaborative robot or a hand attached to an end of the collaborative robot is detected.

TECHNICAL FIELD

The present disclosure relates to an injection molding system.

BACKGROUND

In a known injection molding system, in order to detect that there is no operator left inside a safety door, a light curtain is disposed at least in an area on the side opened by an opening action of the safety door (for example, see Japanese Unexamined Patent Application Publication No. 2017-205932).

SUMMARY

An aspect of the present disclosure is an injection molding system including: an injection molding machine; a collaborative robot installed outside or inside the injection molding machine; and a control unit that controls the collaborative robot. Before the injection molding machine is brought into operation, the control unit operates the collaborative robot at least in a space inside the injection molding machine where molds are installed and transmits an operation disable signal to the injection molding machine when contact between an object and the collaborative robot or a hand attached to an end of the collaborative robot is detected.

DESCRIPTION OF EMBODIMENTS

An injection molding system1according to an embodiment of the present disclosure will be described below with reference to the drawings.

As shown inFIG.1, the injection molding system1according to this embodiment includes an injection molding machine2, a collaborative robot3installed outside the injection molding machine2, and a control unit4that controls the collaborative robot3.

The injection molding machine2includes a machine base5installed on a floor F, and an injecting part6and a clamping unit7installed on the machine base5. The injecting part6injects molten resin into a cavity between molds8and9provided in the clamping unit7.

The clamping unit7includes a stationary platen10that is fixed to the machine base5and supports one mold8, and a moving platen11that is disposed so as to be movable in the horizontal direction with respect to the stationary platen10and supports the other mold9. The moving platen11is supported by four tie bars12extending in the horizontal direction so as to be movable in the horizontal direction with respect to the stationary platen10.

By bringing the stationary platen10and the moving platen11toward each other, the pair of molds8and9are combined, forming the cavity between the molds8and9. After molten resin is injected into the cavity to form a molded article, the moving platen11is moved in a direction away from the stationary platen10. As a result, the molds8and9are opened, and the molded article can be taken out of the molds8and9.

The clamping unit7includes a cover13that covers at least a portion of the outer periphery, and a safety door14that can be opened and closed. In the drawings, reference sign15denotes a guide device that drives the safety door14in the horizontal direction. As shown inFIG.2, the stationary platen10, the moving platen11, and the pair of molds8and9disposed inside the cover13can be viewed from the outside by opening the safety door14.

When the injection molding machine2is brought into operation, as shown inFIG.1, the safety door14is moved in the closing direction and closed, thus restricting contact between an operator and the stationary platen10, the moving platen11, and the pair of molds8and9inside the injection molding machine2. Furthermore, when parts are to be set in the molds8and9to perform insert molding or when a molded article is to be taken out of the molds8and9, the safety door14is moved in the opening direction and opened, as shown inFIG.2. By doing so, it is possible to expose the pair of molds8and9, which are separated in the horizontal direction, to the outside of the cover13.

The collaborative robot3is, for example, a vertical six-axis articulated robot and is installed outside the injection molding machine2, at a position in the vicinity of the safety door14. The operation area of the collaborative robot3extends over the outside and the inside of the injection molding machine2. The collaborative robot3is provided with, at the end of a wrist16, a tool, such as a hand17for taking out a molded article produced by the injection molding machine2from the molds8and9.

The collaborative robot3accommodates a six-axis force sensor (not shown). Contact of an operator or an outside object with the surface or the hand17of the collaborative robot3fluctuates the detection value of the force sensor, thus making it possible to detect contact with any object. The collaborative robot3is operated at a sufficiently low speed and is controlled to stop or slow down when the force sensor detects any contact.

The control unit4includes a memory (storage unit) that stores a preliminarily taught program, and at least one processor for operating the collaborative robot3in accordance with the program stored in the memory. The processor generates a path on the basis of the program, more specifically, the arrangement of the members in the space where the molds8and9are installed, stored in the memory. Furthermore, as shown inFIG.4, the control unit4operates the collaborative robot3upon receipt of an opening signal for the safety door14and an opening signal for the molds8and9from the injection molding machine2(step S1).

In the injection molding system1according to this embodiment, before the injection molding machine2is brought into operation, that is, before an injection molding operation by the injection molding machine2is started, the control unit4causes the collaborative robot3to perform an object detecting operation (step S2). The object detecting operation is an operation for detecting the presence/absence of an unexpected object in the space inside the injection molding machine2by controlling the collaborative robot3in accordance with the program stored in the memory.

More specifically, the object detecting operation is an operation of the collaborative robot3in which the control unit4causes the tool center point (TCP) set to the hand17to move along, for example, a path X shown inFIG.3. By moving the TCP along this path X, it is possible to pass the arm18, the wrist16, or the hand17of the collaborative robot3over substantially the entire area A, which is separated by fine gaps from inner surfaces of a space extending in the horizontal direction between the top surface of the machine base5and the tie bars12below the molds8and9.

The control unit4determines whether the collaborative robot3has detected contact with any object during the object detecting operation on the basis of the signal from the force sensor (step S3). When it is determined that contact has been detected, the control unit4transmits an operation disable signal to the injection molding machine2(step S4), and the processing is terminated.

In step S3, when it is determined that no contact has been detected, the process in step S3is repeated until the object detecting operation ends (step S5). When the collaborative robot3detects no contact with any object until the object detecting operation ends, the control unit4transmits an operation enable signal to the injection molding machine2(step S6), and the processing is terminated.

The injection molding machine2does not start the injection molding operation when an operation disable signal has been transmitted from the control unit4. In contrast, the injection molding machine2automatically starts the injection molding operation when an operation enable signal has been transmitted from the control unit4.

The operation of the thus-configured injection molding system1according to this embodiment will be described.

In the injection molding system1according to this embodiment, before the injection molding machine2performs the injection molding operation, the collaborative robot3is operated in the space where the molds8and9are disposed.

As shown inFIG.3, because the collaborative robot3is operated over substantially the entire area along the path X, along which the arm18, the wrist16, or the hand17passes, except for the vicinity of the inner surfaces of the space where the molds8and9are disposed in plan view of the space, it is possible to detect the presence/absence of an object in the space. This leads to an advantage in that it is possible to more reliably prevent the injection molding machine2from being brought into operation while an operator or an unexpected object is left in the space.

Specifically, because detection is performed by directly touching the object in the space with the collaborative robot3itself or the hand17attached to the collaborative robot3, unlike detection using an optical sensor, precise detection is possible even when the illumination is changed. Furthermore, because the presence of an object in the space is detected with the collaborative robot3, there is no need to separately manage the entry/exit of an object into/from the space, unlike detection with a light curtain.

Although a six-axis articulated robot has been described as an example of the collaborative robot3in this embodiment, the type of the robot is not limited thereto, and a robot of any type may be employed.

Furthermore, an example case where the collaborative robot3is operated only in the lower part of the space where the molds8and9are disposed, i.e., the area A in the space, has been described. When the object to be detected is an operator, because the operator typically works with his/her feet on the top surface of the machine base5, by operating the collaborative robot3only at the lower part, which is close to the top surface of the machine base5, the presence/absence of an operator can be efficiently detected.

Instead, the collaborative robot may be operated not only in the lower part of the space, but also in an area wider than the area A in the space, into which the arm18, the wrist16, or the hand17can be inserted. By doing so, it is possible to detect an operator whose feet are not on the floor F, such as when he/she is standing on the tie bars12, or to detect an object, such as a fixture or an inspection device that should have been removed when the robot is brought into operation, remaining attached to the molds8and9or the like.

Furthermore, in this embodiment, the space above the machine base5is shown as an example of the space where the molds8and9are disposed. In addition to this, when the space inside the machine base5is continuous with the space inside the clamping unit7, as shown inFIG.5, the collaborative robot3may be operated also in the space inside the machine base5.

In the case where molded articles are randomly dropped, sometimes a product drop port area B, serving as a space for placing a container for storing the molded articles or a conveyor for transporting the molded articles, is provided inside the machine base5. By making the collaborative robot3perform an object detecting operation also in the space inside the machine base5, it is possible to reliably prevent accidental entry of an operator who has been working in the product drop port area B before the injection molding machine2is brought into operation into the space inside the clamping unit7during the operation of the injection molding machine2.

Furthermore, in this embodiment, the object detecting operation may be preliminarily stored in the memory by teaching. Alternatively, in a state in which the safety in the space where the molds8and9are disposed or in the space inside the machine base5is confirmed, the collaborative robot3may be operated to search for the positions of the members, such as the molds8and9and the tie bars12, inside the space by using a contact detection function of the collaborative robot3, and the positions may be stored in the memory.

Alternatively, three-dimensional data of the positions of the members, such as the molds and the tie bars12in the space, may be formed off-line by means of three-dimensional CAD or the like and stored in the memory. The control unit4may automatically generate an object detecting operation on the basis of the positions of the members stored in the memory.

In this embodiment, although an example in which the collaborative robot3is installed outside the injection molding machine2has been described, a system in which the collaborative robot3is installed inside the injection molding machine2may be employed.