JPH0788922A - Safety device in tight mold clamping mechanism part of injection molding machine - Google Patents

Abstract

PURPOSE:To prevent the damage of a machine or the accident of an operator by providing a means detecting the breakage of an endless member and energizing the baking force of the brake braking the rotation of a rotary member on the basis of the breakage detection signal given by the detection of breakage. CONSTITUTION:The breakage of an endless member 16 is detected by a breakage detection means detecting the breakage of the endless member 16 for transmitting the rotation of a mold clamping motor 12 to the rotary member connected to the up and down movable part 3 of the tight mold clamping mechanism part 1 of an injection molding machine through a rotary/translational motion conversion means. On the basis of the breakage detection signal given by the breakage detection means, the braking force of the brake means 4 for braking the rotation of the rotary member is energized. Therefore, even when a belt or chain transmitting mold clamping force is broken during the operation of the tight mold clamping mechanism part 1, braking force acts on a rotary body (usually, a ball screw 13) to stop and lock rotary motion. By this constitution, the accident of an operator can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device in a vertical clamping mechanism of an injection molding machine, more specifically,
The present invention relates to a safety device for preventing the vertical mold clamping mechanism part from dropping when an endless member (belt or chain) that transmits a rotational force of a motor that is a drive source for generating a mold clamping force in the mechanism part is broken.

[0002]

2. Description of the Related Art When an injection molding machine is roughly classified according to the positional relationship between an injection mechanism section and a mold clamping mechanism section, a horizontal type machine in which both are arranged in a horizontal direction, a vertical type machine in which they are arranged in a vertical direction, and an eclectic type machine. There are some. The present invention relates to a safety device for preventing a falling accident peculiar to a mold clamping mechanism part (hereinafter, referred to as a vertical mold clamping mechanism part) having a vertical arrangement among them. Therefore, first, a general structure of the vertical clamping mechanism will be briefly described.

FIG. 1 is a partially cutaway front view showing a schematic structure of a vertical clamping mechanism portion. The vertical clamping mechanism portion generally indicated by reference numeral 1 in the drawing is a fixed frame 2 with respect to a fixed frame 2. It has a structure for vertically moving the movable body 3 mounted so as to be vertically movable. A mold clamping motor 12 is used as a drive source for producing the vertical movement, and a brake device 4 is provided as a means for stopping the movable body 3 at an upper position.

The movable body 3 has a structure in which an upper movable platen 5 and a lower die height platen 6 are joined by four tie bars 7, and a fixed platen 8 integrally fixed to the frame 2 is The above-mentioned tie bar 7 is vertically penetrated and attached. The lower die height platen 6 and the fixed platen 8 are connected by a toggle mechanism 9,
Is composed of a toggle link 10 arranged symmetrically on the left and right and a cross head 11 for driving the toggle link 10. The crosshead 11 is moved up and down by the rotation of the ball screw 13 that is driven and rotated by the mold clamping motor 12, and cooperates with the toggle link 10 to rotate the ball screw 13 up and down the movable body 3. It has the function of converting to directional translation. The space between the fixed platen 7 and the movable platen 4 is the mold 1
4 is used as a mold clamping space 15.

The brake device 4 has a built-in disc brake mechanism, and includes a frame 2 and a ball screw 1 of a movable body 3.
3, the movable body 3 is locked so as not to drop from the upward moving position (indicated by the broken line in FIG. 1) when the molded product is taken out or the mold is replaced.
In this case, the braked member that is braked by the disc brake mechanism is the ball screw 13, and the frame 2 is the braking member. As the brake device 4 attached to the vertical clamping mechanism part, a brake device of a type that applies a braking force when the power is cut off is used in consideration of safety during a power failure.

The rotational force of the mold clamping motor 12 mounted on the movable platen 6 is transmitted to the ball screw 13 via the pulley and the endless member (belt or chain) 16. When the ball screw 13 rotates, the cross head 11 moves up and down, and the up and down movement of the movable platen 6 is caused via the toggle link 10 (see the broken line display). As a result, vertical movement of the entire movable body 3 including the movable platen 6 with respect to the external world is realized.

By the way, an endless member (belt or chain) 16 used for transmitting the rotational force of the mold clamping motor 12 to the ball screw 13 during the use of the vertical mold clamping mechanism having such a structure. May break. This is considered to be caused by material fatigue and unexpected excessive load due to repeated use over a long period of time, but the rupture phenomenon often occurs suddenly, and it is difficult to prevent this in advance. .

Then, once the belt or chain 16
If it breaks, the force that restrains the rotation of the ball screw 13 disappears. Therefore, the ball screw 13 is in a free rotation state, and the movable body 3 drops downward by gravity together with the mold clamping motor 12 mounted on the movable body 3. Will be done. If such a breakage accident occurs when the movable body 3 is lifted upward, the fall distance becomes large, which may lead to a damage accident of the mold 14 in use and the vertical clamping mechanism itself. Also,
This may lead to personal injury of the operator who operates the injection molding machine.

[0009]

DISCLOSURE OF THE INVENTION The present invention is directed to a vertically movable part included in a vertical mold clamping mechanism when an endless member for transmitting a rotational force of a mold clamping motor of the vertical mold clamping mechanism is broken. By providing a safety device to prevent accidental fall of the machine, it is possible to avoid damage accidents of the mold and the vertical clamping mechanism itself and protect the operator from the risk of personal injury. is there.

[0010]

According to the present invention, "the rotation of a mold clamping motor is connected to a rotary member connected to a vertically movable part of a vertical mold clamping mechanism of an injection molding machine through a rotation / translational motion converting means. A breakage detection means for detecting breakage of the endless member for transmission, and a means for energizing the braking force of the rotation braking brake means of the rotating member based on the breakage detection signal given by the breakage detection means are provided. The safety device for the vertical clamping mechanism of the injection molding machine, which is characterized by the above. "

[0011]

The safety device of the present invention is for transmitting the rotation of the mold clamping motor to the rotating member coupled to the vertically movable part of the vertical mold clamping mechanism of the injection molding machine through the rotation / translational motion converting means. A breakage detecting means for detecting the breakage of the endless member detects the breakage of the endless member, and based on the breakage detection signal provided by the breakage detecting means, applies the braking force of the rotation braking brake means of the rotating member. Is.

Therefore, even if the belt or the chain for transmitting the mold clamping force is broken during the operation of the vertical mold clamping mechanism, the braking force acts on the rotating body (usually a ball screw) to stop the rotary motion. Locked. As a result, a fall accident of the vertically movable part of the vertical tightening mechanism part at the time of break is avoided, and damage to the machine and personal injury of the operator are prevented.

As the breakage detecting means for detecting breakage of the endless member, it is desirable to use a switch device for promptly detecting breakage of the endless member used. Usable detection switches are various types such as mechanical type, photoelectric type (reflection type and transmission type), magnetic type, electric type (detection of change in electric capacity, electric resistance, etc.), microwave type, etc. Conceivable.

As a means for exerting a braking action on the rotating body when the endless member is broken and stopping / locking the rotating body, a brake device attached to a normal vertical clamping mechanism can be used. Further, in order to energize the braking force of the brake device in response to the breakage detection signal from the breakage detection means, it is possible to use a control device with a built-in CPU for controlling the entire injection molding machine.

[0015]

FIG. 2 is a block diagram showing an outline of a system in which a safety device in a vertical clamping mechanism according to an embodiment of the present invention is connected to a control device of an injection molding machine. In FIG. 2, reference numeral 50 is a control device that controls the entire injection molding machine including a safety device for the mold clamping part, and includes a CPU (central processing unit consisting of a microprocessor) 51 that controls the operation of the control device. . The CPU 51 includes a ROM 52 and a RAM 53 that store various programs for controlling the operation of each unit of the injection molding machine, related data, and the like.
An input / output device (I / O) 54 for exchanging signals with each part of the injection molding machine, and input of programs and data,
Operation panel 57 for inputting commands for manually operating each part
Are connected via a bus 58.

Each part of the safety device connected to the input / output device 54 will be described below (illustration and description of elements not particularly related to the safety device are omitted). First, the voltage detector RV55 connected to the input / output device 54.
In a mode described later, a belt breakage detection switch 60 arranged near the endless member 16 (in this embodiment, a belt. The same applies hereinafter) of the vertical clamping mechanism portion shown in FIG.
Is connected to a DC power source of 24V. This R
The V55 responds to a voltage sensing command sent from the CPU 51 via the input / output device 54 in an extremely short cycle, and sends a signal indicating the open / closed state of the belt breakage detection switch 60 to the CPU 51 via the input / output device 54. send.

The belt breakage detection switch 60 is used for the belt 1
When 6 is normal, the closed state is maintained and the belt is opened only when the belt breaks. Therefore, the RV 55 detects DC 24V when normal, and detects a voltage drop to the ground potential when the belt breaks.

Next, the block designated by reference numeral 56 is
It shows a brake control unit for controlling the brake mechanism 40, which is connected to the input / output device 54 and is
It is connected to the V DC power supply and the brake switching unit 70. The brake switching unit 70 includes a contact 72 for supplying / disconnecting a 90V DC voltage to the brake mechanism 40, and a relay (relay coil) 71 for opening / closing the contact 72. The contact 72 is configured to maintain a closed state while the relay 71 is energized / excited and to maintain an open state while the relay 71 is de-energized. The brake control unit 40 controls switching between the braking state and the non-braking state of the brake mechanism 40 by supplying / interrupting a DC voltage of 24 V to the relay 71 according to a command from the CPU 51.

As described above in the section of the description of the prior art, the brake mechanism 40 is of a type in which the braking force is applied when the power source is cut off, in consideration of safety at the time of power failure. To do. Therefore, the braking force of the brake mechanism 40 is urged and maintained when the contact 72 is opened, and conversely,
The braking force of the brake mechanism 40 is not applied while the contact 72 is closed, and the state in which the rotation of the ball screw 13 of the vertical clamping mechanism is allowed is maintained.

The operation of the above system will be described on the premise of the above configuration and the function of each unit. When the system starts up,
It is assumed that the braking force of the brake mechanism 40 is urged and the rotation of the ball screw 13 of the vertical clamping mechanism is locked. Further, the belt 16 is assumed to be in a normal state.
First, in order to activate the vertical mold clamping mechanism to start the vertical movement of the movable body 3, the keyboard of the operation panel 57 is operated to release the braking force of the brake mechanism 40, and the mold clamping is performed according to the required operation. The rotation of the motor 12 is started. The braking force of the brake mechanism 40 is released by sending a command from the CPU 51 to the DV 56, connecting / exciting the relay 71 to the power source (DC24V), and closing the contact 72.

If the belt 16 is not broken, the work including the mold clamping operation is carried out as usual, and when the work is completed, the energization of the relay 71 is cut off and the braking force of the brake mechanism 40 is applied. Prepare for the next work as a state. On the other hand, if the belt 16 is broken during the work, the belt breakage detection switch 60 is opened. Voltage detection unit RV receiving a sensing command from CPU 51 in an extremely short cycle
55 detects a voltage drop and sends a belt breakage detection signal to the CPU 51. The CPU immediately sends a brake braking force energizing command to the brake control unit DV 56 via the input / output circuit 54 to stop the energization / excitation of the relay 71, and the contact 72.
Open up. As a result, the brake mechanism 40 is powered by (D
C90V), the braking force is applied and the rotation of the ball screw 13 is locked.

By the series of operations described above, even if the belt 16 is broken, the fall of the movable body 3 is prevented, and the damage to the machine and the injury to the operator are prevented. The replacement and repair work of the broken belt 16 can be performed in a state where the braking force urging state (power supply cutoff) of the brake mechanism 40 is maintained.

The belt breakage detection switch 60 for detecting the breakage of the belt 16 may be of any type as long as it has the ability to promptly detect the breakage of the belt 16 (or the chain). . When the detection switches that can be used are classified according to the breakage detection principle, those of mechanical type, photoelectric type (reflection type and transmission type), magnetic type, electric type (detection of change in electric capacity, resistance, etc.), microwave type, etc. Can be mentioned.

Here, a case where a mechanical switch device of the limit switch system is used will be described. FIGS. 3 and 4 are diagrams illustrating a state in which the mechanical switch device of the limit switch system is arranged in the vicinity of the belt 16 of the vertical clamping mechanism portion shown in FIG. 1, and FIG. 3 is a front view thereof. 4 is a diagram, and FIG. 4 schematically illustrates a cross section taken along the line L in FIG. 3. In both figures, reference numeral 10
Reference numerals 7 and 108 respectively denote pulleys connected to the rotary shaft of the mold clamping motor 12 and the ball screw 13, and the belt 16 is suspended on both pulleys. Brake mechanism 40
In the state where the braking force is not applied, the rotation of the mold clamping motor 12 does not occur unless the belt 16 is broken.
Is transmitted to the ball screw 13 via the orbital movement of the. The switch device 60 for detecting the breakage of the belt 16 has a built-in limit switch 61, and converts the breakage of the belt 16 into an electric signal by separating and contacting the movable contact member 65 and the fixed contacts 68a and 68b.

The movable contact member 65 is attached to the spring member 64 whose one end is fixed to the fixed member 66, and is also constructed integrally with the movable plunger 62. A rolling roller 63 is attached to the tip of the movable plunger 62, and is constantly biased to the right in the figure by the action of the spring member 64. The belt 16 has a certain thickness, and in the normal state where the belt is not broken as shown in the figure, the movable contact member 65 and the fixed contacts 68a and 68b are arranged to be surely kept in contact with each other.

This state corresponds to the fact that the belt breakage detection switch device 60 in FIG. 2 described above is in the closed state. That is, the fixed contacts 68a and 68b are respectively connected to the DC power supply (24V) and the voltage detection unit RV55 shown in FIG.

If the belt 16 is broken during the work, the belt 16 is disengaged from the pulley 107, and the rolling roller 63 moves rightward together with the movable plunger 62 and the movable contact member 65 by the action of the spring member 64. Then, the contact of the limit switch is opened. Then, the voltage detection unit RV55, which receives the sensing command from the CPU 51 at an extremely short cycle, detects the voltage drop on the contact 68a side and C
A belt breakage detection signal is sent to PU51. Below, CPU5
The process in which the brake mechanism 40 is immediately disconnected from the power supply, the braking force is applied, and the rotation of the ball screw 13 is locked by the command from 1 is as described above.

Finally, with respect to the brake mechanism built in the brake device 4, a case where a disc brake mechanism attachable to a general vertical clamping mechanism is used for the braking means in the present invention is taken as an example, and FIG. 5 is used. explain.

Referring to FIG. 5, the disc brake mechanism 40 generally includes a disc 18 that rotates with a rotating shaft 17.
The side plate 1 (on the braking side) fixed to the machine casing side
The structure is basically such that a braking force is obtained by pressing the armature 20 against the armature 20, and electromagnetic force is used to drive the armature 20 (hydraulic pressure or pneumatic pressure may also be used).

The disk 18 is usually an inner driver 21 fixed to a rotating shaft 17 (rotating together with the ball screw 13) which is the braked side, and an axial groove such as a spline 22 formed on the outer peripheral surface of the inner driver 21. It is mounted in such a manner that it is fitted to the rotary shaft 17, and is always rotated together with the rotary shaft 17, while being arranged so as to be movable in the axial direction of the rotary shaft 17.

The disc 18 is mounted with a slight allowance set with the inner driver 21 for smooth movement in the axial direction and for lubrication. There is some play, and there is also some play in the direction in which the surface of the disk 18 is inclined with respect to the rotating shaft 17.

Further, referring to the details of the drawing, the disk-shaped side plate 19 and the frame case 23 are fixed by three spacer screws 24 with a space therebetween, and between the side plate 19 and the frame case 23. The disc 18 and the armature 20 are arranged.

The armature 20 is arranged between the disk 18 and the frame case 23, and is movable in the axial direction of the rotary shaft 17 with the spacer screw 24 as a guide. The frame case 23 has an annular storage groove 2 on the inner surface side.
5 is formed, and a coil 26 for generating electromagnetic force and a spring 27 are mounted in this groove 25. Annular brake pads 28 and 29 are attached to the rear surface of the side plate 19 and the front surface of the armature 20.

The armature 20 is pressed from the back side by the spring 27, and the disc 18 is constantly in pressure contact with the brake pad 28 of the side plate 19 via the brake pad 29, and is kept in a braking state unless power is supplied to the coil 26. Yes (negative actuation type). When electric power is supplied to the coil 26, the armature 20 moves to the frame case 23.
Pulled to the side, the restraint of the disk 18 is released.

When the ejection of the molded product is completed and the next injection molding operation is started, or when the replacement of the mold 14 is completed and the injection molding is restarted, the braking by the disc brake mechanism is released and the mold is released. The tightening motor 12 is driven in the direction opposite to that at the time of mold clamping. As a result, the movable body 3 descends and the mold 14 is clamped, but at this time, the disc 18 of the disc brake mechanism whose braking has been released has the rotating shaft 17
And is rotated together with the ball screw 13.

When the belt 16 breaks during the work, the coil 26 for generating electromagnetic force is de-energized, so that the force pulling the armature 20 toward the frame case 23 disappears. Then, the armature 20 is pressed from the back surface side by the spring 27, and the brake pad 2
The disc 18 is pressed against the brake pad 28 of the side plate 19 via 9. As a result, the ball screw 13
Braking force is applied to the rotary shaft 17 of the
The rotation of 3 is locked and the movable body 3 is prevented from falling.

[0037]

According to the safety device for the vertical mold clamping mechanism of the present invention, the endless member (belt or chain) used for transmitting the rotational force of the mold clamping motor 12 to the ball screw (rotating body). Even if a break occurs, the movement of the vertically movable part included in the vertical clamping mechanism is immediately stopped. As a result, it is possible to prevent damage to the mold and the vertical clamping mechanism caused by an accidental drop of a heavy movable portion, and protect the operator from the risk of personal injury.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an outline of a general structure of a vertical clamping mechanism portion.

FIG. 2 is a block diagram showing an outline of a system in which a safety device in a vertical clamping mechanism according to an embodiment of the present invention is coupled to a control device of an injection molding machine.

FIG. 3 is a front view schematically showing the structure and arrangement of the belt breakage detection switch used in the embodiment of the present invention.

4 is a diagram schematically illustrating a cross section taken along a line L in FIG.

FIG. 5 is a sketch drawing illustrating the structure of a disc brake mechanism that can be used in the brake device 4 attached to the vertical clamping mechanism.

[Explanation of symbols]

 1 Vertical clamping mechanism 2 Fixed frame 3 Movable body 4 Brake device 5 Movable platen 6 Die height platen 7 Tie bar 8 Fixed platen 9 Toggle mechanism 10 Toggle link 11 Cross head 12 Clamping motor 13 Ball screw 14 Mold 15 Mold clamping space 16 Endless member (belt or chain) 17 Rotating shaft 18 Disc 19 Side plate 20 Armature 21 Inner driver 22 Spline 23 Frame case 24 Spacer screw 25 Groove 26 Electromagnetic force generating coil 27 Spring 28, 29 Brake pad 40 Brake mechanism 50 Control device 51 CPU (Central Processing Unit) 52 ROM 53 RAM 54 Input / Output Device 55 Voltage Detection Section 56 Brake Control Section 57 Operation Panel 60 Belt Break Detection Switch 61 Limit Switch 6 The movable plunger 63 rolling roller 64 spring member 65 movable contact member 66 fixed member 68a, 68b fixed contacts 70 brake switching portion 71 relay (relay coil) 72 contacts

Claims (1)

[Claims] 1. A breakage of an endless member for transmitting the rotation of a mold clamping motor to a rotary member connected to a vertically movable part of a vertical mold clamping mechanism of an injection molding machine via a rotation / translational motion converting means. An injection molding machine comprising: a breakage detection unit for detecting the breakage; and a unit for energizing the braking force of the rotation braking brake unit of the rotating member based on the breakage detection signal provided by the breakage detection unit. Safety device for vertical clamping mechanism.