JP2592074Y2 - Controller of electromagnetic clutch for ram drive - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for an electromagnetic clutch for driving a ram such as a press machine or a shearing machine utilizing the inertia force of a flywheel.

[0002]

2. Description of the Related Art Conventionally, rams are used in machines such as press machines and shearing machines, and a flywheel having a large inertial force is used as a driving force for driving the ram. In many cases, a large driving force is generated in a short time by controlling the connection with the driving shaft. Some clutches that control the connection between the flywheel and the drive shaft use hydraulic pressure or pneumatic pressure, but many use electromagnetic clutches that use electromagnets. In the apparatus using an electromagnetic clutch, the flywheel is quickly moved in the axial direction of the attachment / detachment portion of the ram drive shaft by an electromagnet to connect or disconnect the flywheel and the ram drive shaft.
Since the flywheel has large inertia, a large current flows in the control circuit of the electromagnetic clutch, and a large back electromotive voltage is generated when the circuit is opened and closed, particularly when the circuit is opened. Therefore, in a switch using a contact switch, a spark discharge is easily generated at a contact, and a switch in which a capacitive load called a spark killer or a noise killer is connected in parallel with a solenoid coil in order to suppress the spark discharge has been used. In addition, a non-contact switch using a semiconductor may be used.

[0003]

In a control circuit using a contact switch, even if a capacitive load is connected in parallel, no spark discharge can be eliminated. For this reason, the switch is quickly worn, and easily causes a malfunction such as a contact failure. In addition, in the case of using a solid state switch of a semiconductor, it is difficult to judge a semiconductor failure from the appearance,
Furthermore, when the failure of the semiconductor switch is in the conducting state, the solenoid coil is always in the excited state, so that a double hit or the like occurs, which causes a problem that safety cannot be ensured.

[0004]

In order to solve the above-mentioned problems, the present invention provides a control circuit for a ram drive electromagnetic clutch of a processing machine, wherein a contact switch and a non-contact switch are connected in series with a control coil of the electromagnetic clutch. The contact switch is turned off after the contactless switch is turned off.

[0005]

In the control circuit of the electromagnetic clutch, the contact switch and the contactless switch are connected in series to the solenoid coil, and the contactless switch is opened before the contact switch is opened. Sometimes no current is flowing through the solenoid. Therefore, spark discharge does not occur even when the contact switch is opened.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the operation of the present invention. FIG. 1A shows a control circuit 1 for an electromagnetic clutch. Contactless switch 1 for opening and closing solenoid coil 11 in circuit 1
3 and a contact switch 15 are connected in series, and this is connected in series to an exciting DC power supply 17. FIG. 1 (B)
This shows an example of the timing for opening and closing the contactless switch 13 and the contact switch 15. First, the contact switch is closed at time t _1, proximity switch is turned on after a time t _b. The current I _SOL does not flow through the circuit 1 between the times t ₁ and t _{2 in} the figure. Therefore, no spark occurs in the contact switch 15.

[0008] Next, the proximity switch 13 is turned off at time t _3, after a time t _a, to turn off the contact switch 15 at time t _4. A large back electromotive force is generated when at time t ₃ turns off the proximity switch 13, the contact switch 15
No spark discharge occurs between these contacts because the contacts are fully conductive. Since at time t ₃ of the current the circuit 1 is interrupted, there is no spark discharge be subsequently opened contact switch.

In the control circuit 1 shown in FIG. 1A, most of the failures in the contact switch 15 are caused by welding of the electrodes, and the broken state is broken in the ON state or broken in the OFF state. You can monitor it. That is, the contact switch has an A contact, a B contact, and a movable contact in the middle thereof. In a normal state, the movable contact is always in contact with either the A or B contact when the electromagnetic coil is turned on or off. By checking whether the electromagnetic coil is on or off and which contact is in contact, it is possible to monitor whether the electromagnetic coil is operating normally or whether one is welded. Therefore, if a setting is made so that the machine operation is stopped when a monitor signal is received and an abnormality is detected, the operation can be reliably stopped.

Consider what happens when the contact switch 15 is changed to a non-contact switch in the control circuit 1 of FIG. First, the non-contact switch is a semiconductor circuit, and it is necessary to connect voltage detection sensors in parallel in order to know whether the switch is broken in either the on or off state.

However, in the control circuit 1 of FIG. 1A, when a contactless switch is set in place of the contact switch 15, when the contactless switch is turned on and off, another switch is turned off. That is, even if it is broken in the ON state, no voltage is generated and cannot be detected by the sensor.

In other words, even if it is broken in the conductive state, the operation can be continued only by the non-contact switch 13. It is important to always provide two steps for safety measures since a failure always accompanies an object, but this state has only one step and is hardly safe.
Further, when the non-contact switch 13 is broken, there is a danger that the non-contact switch 13 will simply pass through the non-contact switch 13 and another non-contact switch and stop far beyond the stop range. Therefore, if another non-contact switch is broken first, the non-contact switch 13 cannot be monitored and cannot cope with it. Therefore, the non-contact switch 13 and the contact switch 15 that can be monitored are combined, and this is connected in series with the solenoid coil 11 for opening and closing. Those connected to will be useful.

FIG. 2 shows a driving mechanism 23 of the electromagnetic clutch in the shearing machine 21 used for carrying out the present invention. In the figure, a flywheel 25 includes a motor 27
And the belt 29 constantly rotates. An armature 31 is fixedly provided on the flywheel 25, and a minute gap g is provided between the armature 31 and the rotor 33, so that the armature 31 is energized when a solenoid coil wound around the magnetic field core 35 is energized. 31 and the rotor 33 are in close contact with each other.

The rotor 33 is connected to a pinion shaft 39, and a small gear 41 provided on the pinion shaft 39 and a main gear 43 mesh with each other, whereby the transmission force is amplified. Further, the drive shaft 45 is fixed to the main gear, and at the same time, is connected to the connecting rod 49 via the eccentric plate 47.
It is connected to. A ram (not shown) is provided at the tip of the connecting rod 49 so that the ram moves linearly. On the other hand, a friction plate 51 and a magnetic field core 53 are provided at the opposite end of the pinion shaft 39 for braking. Since this drive mechanism has such a configuration, when no current is supplied to the solenoid coil, the pinion shaft does not rotate because the drive force is not transmitted from the flywheel and is braked by the friction plate 51. . Also, when electricity is supplied, the friction plate 51
, The rotational driving force is transmitted from the flywheel 25 to the pinion shaft 39. This drives the ram.

FIG. 3 shows a specific example of the control circuit 1 in this embodiment. In FIG. 3, an AC input power supply is converted into an appropriate voltage by a
3 and smoothed by the smoothing circuit 65, and a DC voltage is obtained between the terminals ab. A main switch 67, a solenoid coil 69, a semiconductor switch 71, and a contact relay switch 73 are connected in series between the terminals ab. Semiconductor switch 71, relay switch 73
Are controlled by the control signals S _E and S _M , respectively, as described with reference to FIG. A protection circuit 75 is connected in parallel to the solenoid coil 69 so that a voltage higher than the standard of the semiconductor switch 71 due to the back electromotive force is not applied. A method for generating the control signals S _E and S _M will be described below.

FIG. 4 shows the rotation angle of the crank for moving the ram up and down. In the figure, U indicates the top dead center, and L indicates the bottom dead center. The range ∠COD indicates a top dead center stop allowable range corresponding to the allowable range for stopping the ram. That is, if the crank stops in this range, no inconvenience such as the ram hitting twice will occur. The range ∠COD is generally fixed, and is a normal stop range where the non-contact switch is normally turned off and stopped.

In the drawing, the OFF timing S ₁ of the contactless switch 13 is on the OA line, and the contact switch 15
Timing S ₂ off at will and in OB line,
∠AOB = ∠A'OB '.

[0018] Timing off in proximity switch 13 is realized by the S _1, stopping the coast rotated in ∠COD. However, when the crank rotational speed is changed, so come Hen' also coasting angle of rotation, and electrically changing the timing point S _1. In the figure, S ₁ is operated at a range of ∠AOA '(normal operation).

Next, when the occurred failure to the proximity switch 13, a timing point S ₂ in contact switch 15 is turned off, the S ₂ to stop by over a range of ∠COD after coasting rotation Take the timing. The drive in which overrun is detected is stopped immediately. To take S ₂ to overrun ∠COD, use ∠AOB (∠A'O
It is necessary to take B ') at least for ∠COD. In this way, the contact switch 15 in S ₂ is in the off has been the case, so that the stop in the range of crank angle ∠DOE. Since I took ∠AOB for at least ∠COD,
∠DOE is at least ∠COD.

Further, ΔDOE is an overrun amount, and the smaller the overrun amount, the better and the danger is reduced.

That is, ∠AOB should be taken at least for ∠COD, and ∠DOE (= ∠AOB) should be minimized. Therefore, ∠AOB = ∠COD is desirable.

By making the timing for turning off the non-contact switch and the contact switch as described above, during normal operation, the crank stops in the normal stop range, and when the non-contact switch fails due to conduction, Stop outside the dead center stop allowable range. Further, even if the contact switch fails first, monitoring can be performed as described above, so that safety measures can be taken. Also, during normal operation, spark discharge does not occur without high voltage due to back electromotive force acting on the contact switch.

As shown in FIG. 1B, when the non-contact switch and the contact switch are turned on, the contact switch is turned on, and when sufficient contact is secured, the non-contact switch is turned on. When the contact switch is turned on, the contactless switch may be turned on using the detection signal. For example, it can be performed using one of the contact relays. The timing for turning on the contact switch can be set regardless of the crank angle.

[0024]

[Effects of the Invention] As described above, according to the present invention,
During normal operation, spark discharge does not occur in the contact switch, so that the contact switch has less failure. Furthermore, even if the contactless switch fails in the conductive state, even if the contact switch fails first, there is no problem such as double hitting, and the safety against failure is ensured. can get.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining the contents of the present invention.

FIG. 2 is a partial explanatory view of a shearing machine to which the present invention is applied.

FIG. 3 is a control circuit diagram showing an embodiment of the present invention.

FIG. 4 is a diagram showing the timing of turning off a contactless switch and a contact switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic clutch control circuit 11 Solenoid coil 13 Contactless switch 15 Contact switch 21 Shearing machine 23 Electromagnetic clutch 25 Flywheel 31 Armature 33 Rotor 35 Magnetic field core 39 Pinion shaft 47 Eccentric plate 49 Connecting rod

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16D 48/06 B30B 15/12

Claims (3)

(57) [Scope of request for utility model registration] In a control circuit of a ram drive electromagnetic clutch of a processing machine, a contact switch and a non-contact switch are connected in series with a control coil of the electromagnetic clutch, and the contact switch is turned off by the non-contact switch. A ram drive electromagnetic clutch controller characterized in that it is turned off after turning off. 2. The controller of a ram drive electromagnetic clutch according to claim 1, wherein the contact switch is turned on before the non-contact switch is turned on. 3. A rotation angle of a crank for driving a ram, wherein an angle from a time when a contactless switch is turned off to a time when a contact switch is turned off is at least the same as the angle of the top dead center stop allowable range when the crank is normal. The ram drive electromagnetic clutch controller according to claim 1 or 2, wherein: