US3035130A - Safety device for appliances which perform successive programmed operations - Google Patents

Description

May 15 1962 v. DAcHKEvlTcH 3,035,130

SAFETY DEVICE Foa APPLIANCES WHICH PERFORM succEssIvE: PROGRAMA/IED OPERATIONS May 15 1962 v. DAcHKl-:vn'cH 3,035,130

SAFETY DEVICE FOR APPLIANCES WHICH PERFORM SUCCESSIVE PROGRAMMED OPERATIONS Filed Aug. 12, 1959 2 Sheets-Sheet 2 United States Patent O 3,035,130 SAFETY DEVICE FOR APPLIANCES WHICH PER- SUCCESSIVE PROGRAMMED OPERA- Vsevolod Dachkeviteh, Neuilly, France, assignor to Cornmissariat a IEnergie Atomique, Paris, France Filed Aug. 12, 1959, Ser. No. 833,282 Claims priority, application France Aug. 27, 1958 6 Claims. (Cl. 200-47) The present invention relates to a safety device which may be iitted to appliances which perform successive and programmed operations. It has the object of stopping the appliance for a check to be made on its working, so as to prevent it from performing an operation which must not be carried out unless another operation has been previously performed or a certain condition previously reached. It thus enables precautions to be taken against the dangers of forgetting the operation or of any member not working (jamming of a relay, sticking of contacts for example).

The device to which the invention relates may be used in particular to ensure safety in working an automatically or semi-automatically controlled handling machine. For example, it will prevent the load from colliding with an obstacle (door, cover of a receptacle etc.) which may not have been withdrawn for any reason, from reaching or passing a dangerous position if the normal supervisory members are not working, or of starting a movement before the movement in progress has been finished.

According to the present invention there is provided a safety device for appliances which perform successive programmed operations characterised in that it comprises a combination, in a frame, of a cursor which is movable along a definite trajectory in synchronism with the motor of the appliance, a movable abutment holder comprising one or more abutments suitably situated on the holder and capable of being withdrawn or brought into the path of the slider, the said holder normally occupying a position which allows the appliance to work, and being movable to a position, under the action of thrust by the cursor on any of the abutments during operations, which stops the appliance, and means for bringing the abutments into the active position or for causing them to be withdrawn, as a function of the operations in the programme which they are supervising.

The safety device to which the invention relates thus operates as follows:

When starting the appliance which is to have its working supervised, certain abutments are withdrawn, and others are on the contrary placed in the active position in the path of the slider, according to the programme for which instructions have been given` As the programme for which instructions have been given is performed, the cursor moves progressively, and correct performance of the operations being supervised causes the corresponding abutments to be withdrawn, and they thus do not offer any resistance to the cursor going past. If for any reason one of these operations is not performed at the desired time, the corresponding abutments remain in the 4active position; the cursor then comes into collision with it, drives the movable holder and stops the appliance. In this case, the abutment holder must be put back into place in order to re-establish the initial conditions, so that the appliance may be started up again after the mistake which was made has been corrected, or the cause of nonworking which occasioned stoppage has been eliminated.

The trajectory of the cursor and the position and number of the abutments must be determined as a function, on the one hand, of the programmes of operations which the appliance can perform, and on the other hand of the "ice conditions under which it is desired to have the said operations proceed.

The safety device according to the invention thus forms a unit which represents in analogical form the working of the appliance which it is desired to supervise; in this analogica] unit the position of the cursor represents the state to which the cycle of the appliance has advanced, each abutment a safety means which can stop the appliance, and the position of each abutment the instant on the cycle at which this event may occur.

In a particular embodiment of the invention, the safety device exhibits the following features, taken separately or in various combinations:

The cursor is a guided nut, rotationally locked and displaced in one direction or the other by a screw which is itself driven by the motor of the appliance by means of a suitable transmission.

The movable abutment holder consists of a cross-member which can slide in both directions on supports provided on the framework on either side of a suitably marked position of balance. Displacement of the said member with respect to the said position, as soon as a certain `amplitude is reached, suddenly frees a switch interposed in the power-supply circuit of the electric motor of the appliance. In addition to the retractable abutments, the movable cross-member'is equipped with fixed stroke-terminating abutments.

The abutments, which are normally disposed in the path of `the cursor under the action of their own weight or of springs, are withdrawn by electromagnets which are energised either under the control of a selector or control change-over switch in the appliance, or by circuits being closed due to performance of the operations to be supervised.

This embodiment is particularly suitable for a safety device iitted to a handling machine which performs reciprocating movements starting from a parked position. The cursor likewise moves in one direction or the other according to the direction in which the handling machine moves.

Moreover, it confers complete safety, since any breakdown in the device, in particular in the electro-magnets or the circuits which energise them, has the effect of stopping the appliance.

In order that the present invention may be well understood there will now be described one embodiment thereof, given by way of example only, reference being had to the accompanying drawings in which:

FIGURE l illustrates a sectional elevation of a safety device according to the invention;

FIGURE 2 illustrates a transverse section through the same device along AA in FIGURE l;

FIGURE 3 illustrates a transverse section through the same device along BB in FIGURE 1;

FIGURE 4 is a detailed illustration on a larger scale, being a longitudinal section through the members which position the movable cross-member on the framework;

FIGURE 5 is a detailed illustration on a larger scale, being a longitudinal section through the members of the movable cross-member which serve as an abutmentholder and to stop the appliance.

The framework of the device to which the invention relates (FIGURES 1 to 3) consists of two horizontal frames 1 made of profiled members joined by two vertical cheeks 2. The said framework supports the cross-member 3 which is capable of translational movement along its longitudinal dimension (as explained later), and serves as [an abutment-holder. The nut 4, which is moved by the screw 5 rotating in the bearings 6 in the cheeks 2, is guided by a bar 7 fixed in the bores 8 in the cheeks 2. A sprocket 9 intended to actuate the screw 5 is keyed to the end thereof; it is connected by a chain 41 to the driving motor 39' of the `appliance 40 which it is desired to supervise.

The movable cross-member 3 rests on the framework 1 by way of the bearing plates and 11 which have machined surfaces and are attached to the cheeks 2, and similar plates 12 and 13 attached to the movable cross-member. The bearing plate 10 (FIGURE 4) comprises a channel 14, while the plate 12 on the cross-member is equipped with a catch 15 which engages in the channel 14 and thus determines the normal position of the movable cross-member 3. In order to limit the movements of the said movable cross-member 3, the latter has button-holes 16 through which there pass rods 17 (FIG- URES l and 3) fast with the framework 1.

The movable cross-member 3 holds the retractable abutments 18, 19, 20, whereof one, the `abutment 19, is illustrated in the active position, and the other two, the abutments 18 and 20, in the inactive position. These abutments are attached to the rods 21 which are rigidly connected to the cores of the electromagnets 22, the latter being attached to the movable cross-member 3. The rods 21 are guided in the bores in the plates 23 attached to the lower face of the movable cross-member. The retractable abutments 18, 19, are controlled by Way of the electrical connections 42 as the cycle of the appliance 40 proceeds. The movable cross-member 3 is likewise fitted with stroke-terminating abutments 24 which are attached by way of holders 25.

The position of the abutments 18, I9 and 20 with respect to the rods 21, and of `the abutments 24 with respect to the holders 25, is adjustable in order to give a slight variation of the position at which the nut 4 on the screw 5 cornes into contact with each abutment while it is being displaced in one or the other direction. An abutment is adjusted by screwing it up or unscrewing it in the threads, not illustrated, with which the rods 21 or the holders 25 are provided for this purpose.

The movable cross-member 3 has a vertical abutment 26 (FIGURES l and 5) on its upper face. In FIGURE l, the abutment 26 is situated at one end of the crossmember, but this position is not absolutely necessary. A rod 27 (FIGURES l and 5), whereof the end is of the same width as the abutment 26, bears against the latter. The rod 27 is guided `in the bores in the plate 28 supporting the switch 29 on the one hand, and in the plate 30 supported by a column 31 bearing on the plate 28 on the other hand.

The rod 27 is caused to bear against the abutment 26 by a spring 32 compressed between the plate 30 and an adjustable ring 33 on the rod 27.

A lever 34 engages at one end in a button-hole in the upper part of the rod 27. This lever is supported by way of a spindle by the cap 3S mounted on the co-lumn 31. The other end of the lever 34 is connected by way of a link 36, articulated about the spindles 37, to the counterweight 38 of the switch 29.

As soon as the lower end of the rod 27 is no longer held back by the abutment 26, because of sliding of the cross-member 3, `the spring 32 expands and moves the rod 27 downwards (position in mixed line in FIGURE 5), thus causing the lever 34 to tilt and the counterweight 38 to rise by way of the link 36, with the result that the electric current feeding the motor 39I of the appliance 40 is cut off.

With the abutments arranged as illustrated in FIG- URE l, the nut 4, when it moves to the right, cannot go appreciably beyond the position marked by the abutment 19 if the latter has not previously been withdrawn.

In fact, as soon as it comes into contact with the said abutment, it displaces the movable cross-member 3 to the right, thus causing the current supplied to the appliance 40 to be cut off.

Likewise, should the appliance continue to work, the nut 4, moving to the left, cannot go appreciably beyond the position marked by the abutment 24 without pushing the movable cross-member 3 to the left, and automatically stopping the appliance 40 as before.

In order to allow `the appliance 40 to start working again `after having been stopped by the safety device, the rod 27 must be lifted abo-ve the abutment 26, the nut 4 must be freed from the abutment which it pushed back when it lifted, and the movable cross-member 3 must be manually returned to its normal position which is marked by engagement of the catch 15 in the channel 14.

The safety device which has thus been described uses members, chiefly of mechanical type, which are simple to construct and fit up, and moreover do not require any accurate machining.

What is claimed is:

l. In a safety device for an appliance, driving means for the appliance, a frame, a screw mounted for rotation in said frame, said driving means rotating said screw, a guide bar on said frame parallel to said screw, a cross member extending the width of said frame mounted for limited movement parallel to said screw on said frame, a switch for said driving means mounted on said frame, a nut mounted on said screw for movement therealong, said nut slidably engaging said guide bar, at least one abutment mounted on said cross member for engagement by said nut, each of said abutments comprising a holder secured to said cross member and a stud threaded through said holder and extending parallel to said screw in the path of said nut, and means actuated by movement of said cross member for opening said switch.

2. In a safety device as described in claim l, solenoid actuated means for selectively retracting said abutments out of engagement by said nut.

3. In a safety device as described in claim 1, a boss on said Cross member, and said means for opening said switch including a switch arm for said switch, a counterweight on said switch arm, a lever and link for moving said switch arm, and a rod resiliently biased into engagement with said boss and articulated to said lever.

4. In a safety device as described in claim l, means for selectively retracting said abutments out of engagement by said nut, each of said means including an electromagnet mounted on said cross member and a holder of magnetic material mounted for movement in said cross member for actuation by said electro-magnet.

5. In a safety device as described in claim l, parallel end members for said frame, bearings in said end members for said cross member and means carried by said end members for limiting the movement of said cross member in said bearings.

6. In a safety device as described in claim l, said driving means being an electric motor, said switch being connected into the electric circuit for said electric motor whereby when said switch is open said motor is de-energized.

References Cited in the le of this patent UNITED STATES PATENTS 2,197,572 Renholdt Apr. 16, 1940 2,431,929 Goff Dec. 2, 1947 2,586,552 Moss Feb. 19, 1952

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