WO1993006961A1

WO1993006961A1 - Protection device for sawing apparatus

Info

Publication number: WO1993006961A1
Application number: PCT/BE1992/000041
Authority: WO
Inventors: James Paul Delbeke
Original assignee: Alpine Engineered Products, Inc.
Priority date: 1991-10-04
Filing date: 1992-10-02
Publication date: 1993-04-15
Also published as: BE1005437A5

Abstract

A protection device for a sawing apparatus (1) comprising a frame (16) which contains one or more circular saws (2) and one or more supports (3) for a workpiece (12) to be shaped. The device comprises a switch mounted in a circuit for supplying the power needed to drive the movements of the saw(s) (2) relative to said support(s) (3) or said frame (16), as well as a proximity sensor (32) for sensing the proximity of one of the circular saws (2) relative to the support(s) (3) or the frame (16), and controlling said switch so as to prevent the saw(s) (2) from damaging or being damaged by the support(s) (3) or the frame (16). Said sensor includes at least one signal transmitting unit (2) and at least one signal receiving unit (35) which are mounted on a member or portion (40) of the support (3), the frame (16) or the saw(s) (2). The signal allows the proximity of the saw(s) (2) relative to the support(s) (3) or the frame (16) to be determined in such a way that when the signal reaches a value corresponding to a minimal proximity, the receiving unit (35) operates the switch. Said device comprises an actuator (41) for moving the transmitting unit (2) during the positioning of one or more saws relative to the frame and/or the support(s), and/or before a sawing operation. The rod (46) of the actuator (44) engages an arm (42) which is connected by means of a pivot to the member or portion to be protected, and supports the receiving unit or the transmitting unit.

Description

PROTECTIVE DEVICE FOR SAWING APPARATUS

The present invention relates to a protective device for a sawing apparatus consisting of a frame in which are mounted one or more circular saws and one or more supports of a workpiece to be shaped. The protection device comprises, on the one hand, a switch mounted in a circuit intended to bring the energy necessary to actuate the movements of one or saws relative to said support (s) or frame and, on the other hand, a proximity detector of a saw or circular saws relative to the supports or frame. The detector controls the switch to prevent one or more saws from damaging the support (s) or the frame.

The detector comprises a member transmitting a signal and a member receiving said signal, said signal being intended to determine the proximity of one or more saws relative to the supports or frame, so that when this signal reaches a predetermined value corresponding to the minimum proximity, the receiving organ controls the switch.

Such a device is known from document BE 08801356. This known device further comprises means intended to move the receiving member and / or the sending member, so as to move it away from the element on which it is mounted during of an operation of positioning a saw with respect to the frame and / or support and / or so as to bring it closer to the element on which it is mounted during the sawing operation. In one embodiment shown in document BE 08801356, the receiving member is mounted on a leaf spring, one end of which is fixed to the element, while on the other end acts the rod of a piston.

In another embodiment according to docu¬ ment BE 08801356, the receiving member is mounted on a leaf spring, one end of which is secured to a support plate fixed to the rod of a piston. The displacement of the receiving member with respect to the element to be protected is obtained by sliding a part secured to the receiving member on a ramp carried by the element.

In these embodiments, the receiving member is only able to undergo a translational movement relative to the element to be protected. Such translational movement is limited so that a circular saw can be brought over a support for wooden parts to be machined, the safety device not being able to detect the presence of the circular saw.

When the circular saw is put into rotation, the latter is subjected to vibrational movements so that the circular saw can damage the support of the wooden parts to be machined or a finger of the system for moving the wooden parts to to machine.

In addition, if the receiving member is moved so as to be brought above the support, any malfunction of the piston will result in damage to said receiving member by the wooden parts to be cut.

The present invention aims to remedy these drawbacks. In addition, it relates to a safety device which, in the event of accidental contact of the receiving member with the blade of a circular saw, allows this member to pivot so as to avoid excessive damage to said member.

The protection device according to the invention is a device of the type described in the first paragraph of this memo. This device comprises a jack intended to move the receiver member and / or the transmitter member during an operation of positioning one or more saws relative to the frame and / or support (s) and / or before a sawing operation. The actuator rod acts on an arm connected to the element or part to be protected by means of a pivot on which the receiving member or the emitting member is mounted. Advantageously, the element to be protected is the conveyor for moving the pieces to be sawed. According to one feature, the means is an arm, one end of which is connected by a pivot to the element or part to be protected, a hydraulic, pneumatic, electric or magnetic mechanism acting on said arm so as to cause it to pivot during a saw positioning operation and / or before a sawing operation.

According to another particular feature, the arm is subjected to the action of an elastic means intended to bring it back to a predetermined position. In one embodiment, the mechanism for moving the arm is a jack having a rod acting on the arm at a point distant from the pivot, the jack rod being pivotally connected, while the jack is pivotally connected to the support or frame or part thereof.

Other particularities and details of the invention will emerge from the following detailed description in which reference is made to the accompanying drawings. In these drawings:

- Figure 1 is a schematic perspective view of a sawing apparatus comprising two circular saws, one located to the left of a frame, the other located to the right of said frame;

- Figure 2 is an elevational view of a device according to the invention;

- Figure 3 is a sectional view along line III-III of the device shown in Figure 2, - Figure 4 is an elevational view of an embodiment of a device according to the invention;

- Figure 5 is a cross-sectional view along line V-V of the embodiment shown in Figure 4; FIG. 6 is a variant of the form of embodiment shown in FIG. 5, and

- Figures 7 and 8 show a conveyor and a feature of it which can be provided with a device according to the invention. In these figures, the same reference notations designate identical or similar elements.

Figure 1 schematically shows a sawing apparatus 1 comprising several circular saws 2 placed on either side of a support 3 of parts to be cut. This support 3 consists of a pair of conveyors 4 and pressers 5. The conveyor 4 and the presser 5 consist of a frame provided at each end 7 with a toothed wheel 8, and a chain 9 s' extending between two wheels of the same frame 6. The chain 9 of the conveyor carries a series of fingers 10. At least one wheel 8 of each frame 6 is driven by a motor 11, so as to set in motion (arrow R) the chain 9. Thus, the chain 9 of the conveyor 4 allows the movement of parts 12 to be machined by sawing (shown in broken lines) of which one side 13 takes press against a finger of this chain 9.

The circular saws 2 are mounted on a shaft of a motor 14 associated with a plate 15 movable relative to the support 3 and relative to a frame 16 on which the support 3 is supported.

The plate 15 can be moved vertically relative to the frame 16 by means of a jack 17 fixed to the frame 16. The rod 18 of the jack 17 is integral with the plate 15.

Finally, the plate 15 carries a jack 28 acting on a platform 29 sliding in guides 30 of the plate 15.

The motor 14 is integral with a plate 19 having the shape of a circular sector, this plate 19 being articulated to the platform 29 (arrow A).

The plate 19 is provided on an edge of teeth 20 meshing with teeth 21 with a wheel 2'2 mounted on a shaft of a motor 24. This motor thus makes it possible to angularly position the saw 2 relative to the support 3.

The presser 5 can be brought closer to the conveyor 4 by means of jacks 25 bearing on the frame and the rod of which is integral with the presser 5.

The frames 6 can be moved towards or away from each other (arrow B) by means of jacks 31 bearing on the frame 16.

Figure 2 shows in elevation a protective device 32 for a sawing apparatus, such as that shown in Figure 1. This device comprises, on the one hand, a switch mounted in a circuit (not shown) intended to bring the energy required to activate the movements of one or more saws 2 and, on the other hand, a proximity detector 33 of one or more saws 2 relative to the supports or frame. This detector 33 is, for example, a difference detector potential mounted in a circuit connecting a wing 35 of the receiving member to a current source 36. A resistor 37 is placed between said source 36 and the detector 33. The wing 35 (conductive element) is mounted at one end of two elastic blades 38, each of said blades taking, at its other end, support on a base 39 fixed on an element or part 40 of the support or frame. The base 39 is made of an electrically insulating material. When the saw 2 brought to an electrical potential different from the wing or receiving member 35 comes into contact with said wing, a potential difference is detected by the detector 33, the latter then controlling the switch mounted in the circuit bringing the energy required to move the saws. In this case, saw 2 plays the role of an emitting organ.

The device comprises means 41 intended to move the receiving member 35 during a saw positioning operation and before a sawing operation. This means 41 comprises an arm 42 carrying the wing 35, this arm being connected to the support 3, on the one hand, by a pivot 43 and, on the other hand, by an element intended to allow the pivoting of the arm around said pivot . This element is advantageously a jack 44 whose one end is fixed by means of a pivot 45 to the support 3 and whose free end of the rod 46 is fixed by means of a pivot 47 to the arm 42. The pivot 47 is distant of the pivot 43, so that the displacement of the rod out of the jack causes a rotation R of the arm 42 so as to bring the free end of the arm to a level lower than the upper level N of the support 3. During this rotation R, the jack pivots (arrow S) also around the pivot 45. The position of the arm 42, when the rod is completely extended from the jack, is shown in broken lines. During an operation of positioning a saw relative to the support 3, the rod 46 of the jack 44 moves (arrow V) towards the pivot 45 of the jack 44 and thereby subjects the arm 42 to traction, the latter causing the arm 42 to rotate (Z) around the pivot 43, so as to bring the upper end of the wing 35 to a level greater than the level D of the free ends of the fingers 10.

Thanks to the device according to the invention, it is possible to ensure protection of the fingers of the support 3, something impossible by means of devices of the known type.

In addition, by placing the jack on the right side of the arm, a circular saw rotating in the clockwise direction which, due to an error, comes into contact with the arm 42 will cause the arm R to pivot, so that the damage may be limited or avoided.

Finally, if 'the wooden pieces were moved from right to left (arrow M) and came into contact, due to an error, with the arm 42, the latter would pivot around the pivot 43 (arrow R), so that the wing 35 and the arm 42 would not be damaged. The axis of the pivot 43 extends in a direction perpendicular to the plane in which the fingers 10 move or in a direction perpendicular to the direction of advancement of the fingers 10.

Thanks to the blades 38, the distance separating the wing 35 from the arm 42 in a direction parallel to the axis of the pivot 43 can be modified. Thus, if a saw 2 comes into contact with the wing 35, the latter can take up, thanks to the blades 38, a pressure force from the saw on the wing 35. If the saw is in rotation when it touches the wing 35 , the rotational force can be partially or totally taken up by the rotation of the arm 42 around the pivot 43. Advantageously, the jack 44 is provided with a return means (spring) 60 for bringing the arm back to the posi¬ tion shown in broken lines.

In the embodiment shown in FIGS. 4 and 5, the arm 42 carrying the wing 35 is mounted on a pivot 43 secured to the support 3.

A jack 44 fixed on the support 3 is used to pivot the arm 42. The free end of the rod 46 of the jack 44 is folded so as to form a shaft 50 around which a roller 51 can rotate. This roller 51 is partially engaged in a groove 52 presented by the arm 42. This groove 52 is intended to transform the reciprocating movement of the rod 46 (arrows V and Q) into a rotational movement of the arm (R, T). The position of the arm 42 shown in Figure 4 corresponds to that when positioning a saw. In this position, the piston 53 of the jack is halfway in the chamber 54, that is to say an intermediate position in the chamber. In this way, when the piston 53 is adja¬ cent of an extreme position 55, 56 of the chamber 54, the arm 42 will be brought into a position (shown in dashed lines) located below the upper level N of the support 3. Such a device makes it possible, during an error such as the non-operation of the jack 44 to bring the arm back to an extreme position, to ensure that the arm 42 is brought to an extreme position without damage to the wing 35. Thus, for example, when a wooden workpiece moved by the finger 10 in the direction of the arrow comes to touch the arm 42, the latter pivots in the direction of the arrow R. Due to this pivoting, the rod 46 and the piston 53 are moved in the direction of the arrow V, so that the fluid, such as air, present in the part of the chamber 54 adjacent to the end 55, is compressed. The jack 44 is provided with safety valves 57, 58, the latter opening during accidental overpressure and thus allowing the pivoting of the arm 42 and its retention after pivoting in a position situated below the upper level N of the support 3.

In this embodiment, the arm 42 pivots about the axis of the shaft 43 in a plane parallel to the plane of movement of the fingers 10 of the conveyor 3.

The wing 35, thanks to the blades 38 is, in turn, able to take up a pressure force from the saw 2 on the wing, in particular the component of the force parallel to the axis of the pivot 43. This avoids subjecting the arm 42 and therefore its pivot 43 to a pressure force in a direction parallel to the axis of the pivot. This therefore avoids subjecting the pivot

43 to a torsional force between the end of the pivot connected to the support or conveyor 3 and the end of the pivot connected to the arm 42.

When the saw 2 in rotation touches the wing 35, the latter is subjected, on the one hand, to a pressure force, force partially or totally taken up by the leaf springs 38 and, on the other hand, to a force of torsion due to the rotary movement of the saw 2. This torsional force is at least partially taken up by the arm 42 thanks to a pivoting of the latter around its pivot 43.

This therefore makes it possible to minimize the risk of damage to the wing 35, the leaf springs 38 and the saw 2.

In the embodiment of Figure 6, the arm 42 is similar to that shown in Figure 5, except that the wing 35 is mounted at one end of two elastic blades. Each of said blades takes support at its other end, with the interposition of a base 39, on the arm 42. To reduce as much as possible the torsional forces generated in the blades, one of the said blades is supported in the vicinity of the pivot 43 of the arm 42. So advantageous, the support points P1, P2 of the blades 38 are located on the same side of the arm 42 relative to the pivot 43, that is to say if the support point Pi is adjacent to a free end of the arm 42, the point P2 is located between the pivot 43 and the point Pi. It goes without saying that the arm 42 can also be provided with a means of the type described in BE 08801356 for moving the wing 35 away from the arm when of a positioning operation and / or to bring said wing closer during a sawing operation. FIG. 7 shows a conveyor 100 of a sawing apparatus of the type described in application GB-A-2006107, a conveyor advantageously provided with a protection device according to the invention. This conveyor 100 consists of a chain 102 extending between two wheels 103, 104 carried by a frame 117. The wheel 103 is toothed and driven by a motor by means of a square shaft 106 for example. The rotation (arrow RI) of the wheel 103 causes the chain 102 to move. The chain 102 carries a series of tabs 107 on one edge of which a face 108 of wooden parts to be machined is supported.

The wheel 104, which may or may not be toothed, is subjected to the action of a means 109 intended to subject said wheel 104 to a force F tending to move it relative to the wheel 103, so as to ensure that the chain 102 is stretched during the entire operating time of the conveyor. The tension of this chain will preferably be kept constant and can be adjusted. Figure 8 shows on a larger scale an embodiment of a device intended to ensure that the chain 102 is tensioned. This device comprises a support 111 carrying a shaft 112 on which is mounted a wheel 104 shown in broken lines and a means such as a spring 113 intended to subject said support 111 to a force F intended to tension the chain 102.

The wheel support 111 or more precisely the edges 114, 115 of the latter slide along guides 116 integral with the frame 117 of the conveyor. The guides 116 consist of two slides.

The spring 113 is, for example, a helical spring wound around a guide rod 118 which can slide in a sleeve 119 integral with the frame 117. This helical spring could have been replaced by a leaf spring, a rubber block, etc.

The rod 118 is threaded, so that it can be fixed on the support 111 by means of a nut 120 and a lock nut 121 screwed onto the rod 118. Between said nut and lock nut extends a part 122 of the support, this part having an orifice giving passage to said rod 118.

The rod 118 is also provided with a stop 124 intended to limit its stroke relative to the sleeve 119.

The rod 118 can also be provided with a member for adjusting the tension of the spring 113.

This member may, for example, be constituted by a nut possibly associated with a lock nut screwed onto the threaded rod, this nut having a face on which one end of the spring bears.

The spring 113 is then compressed either between the support 111 and said member, or between the sleeve 119 and said member. As shown in FIG. 8, it is possible to use, thanks to this device, a wheel whose diameter D3 is equal to twice the pitch P3 of the chain 102.

Preferably, such a device acts on a deflection wheel which can be toothed or be only a simple roller. However, this device could have acted on the drive wheel.

Claims

1. Protective device for a sawing apparatus (1) comprising a frame (16) in which are mounted one or more circular saws (2) and one or more supports (3) of a part (12) to be shaped , this device comprising, on the one hand, an interrupter mounted in a circuit intended to bring the energy necessary to actuate the movements of one or saws (2) relative to said support (s) (3) ) or frame (16) and, on the other hand, a proximity detector (32) of one or circular saws (2) relative to the support (s) (3) or frame (16), this detector controlling said switch so as to prevent one or more saws (2) from damaging the support (s) (3) or the frame (16) or being themselves damaged (s) by the support (s) (3) or frame (16), said detector comprising at least one member transmitting (2) a signal and at least one receiving member (35) of said signal, these members being mounted on an element or part (40) of the support (3), frame (16) or saw (s) (2), this signal making it possible to determine the proximity of one or saws (2) relative to the support (s) (3) or to the frame (16) so that when this signal reaches a value corresponding to the minimum proximity, the receiving member (35) controls the switch, this device comprising a jack (41) intended to move the transmitting member (2) during an operation of positioning one or more saws relative to the frame and / or support (s), and / or before a sawing operation, characterized in that the rod (46) of the jack (44) acts on an arm (42) connected to the element or part to be protected by means of a pivot and on which is mounted the receiving member or the transmitting member.

2. Device according to claim 1, characterized in that the jack (44) has a rod (46) acting on the arm at a point distant from the pivot (43), the rod (46) of the jack being pivotally connected to the arm (42), while the jack (44) is pivotally connected to the support (3) or frame or part thereof.

3. Device according to claim 1 or 2, characterized in that the arm is subjected to the action of an elastic means (60) intended to bring it back to a predetermined position.

4. Device according to any one of the preceding claims, characterized in that the receiving member (35) has a wing (35) attached to said arm (42) by at least one elastic blade (38).

5. Device according to any one of the preceding claims, characterized in that the transmitting member is a saw (2) and the receiving member (35) consists of a conductive element mounted on at least one base (39) in electrically insulating material, so that the receiving member (35) is electrically isolated from the element or part ( _. 40) of the support (3) or frame (16) on which it is mounted.

6. Device according to claim 1, characterized in that the rod (46) of the jack carries at its free end a shaft (50) around which a roller (51) can freely rotate, the latter (51) being engaged in a groove (52) of the arm (42) pivotally mounted on the support (3) or constructed so as to transform the movement of the rod (46) into a rotational movement of the arm (42).

7. Device according to claim 4, for protecting the support (3) of the wooden pieces to be machined, said support comprising at least one conveyor, fingers (10) of which are entrained to allow the movement of the wooden pieces to be machined, characterized in that the jack (44) is such that it acts on the arm (42), so as to bring, during a positioning operation, the upper end of the wing (35) to a level (D) higher than the level of the free ends of the fingers (10) and so as to allow the arm (42) to pivot when it contacts a workpiece.

8. Device according to claim 7, characterized in that the jack (44) has a piston

(53) capable of moving in a chamber (54), the extreme positions of the piston in the chamber corresponding to a position of the arm (42) for which it is located below the upper level of the support (3) while 'an intermediate position, preferably mid-stroke, of the piston in the chamber corresponds to the position of the arm (42) during a positioning operation.

9. Device according to claim 8, characterized in that the jack is provided with safety valves (57, 58) intended to allow, in the event of accidental overpressure, the pivoting of the arm (42) and its maintenance after pivoting in a position located below the upper level (N) of the support (3).

10. Device according to claim 4, characterized in that the wing (35) is attached to the arm (42) by at least one elastic blade whose bearing point on the arm (42) is adjacent to the pivot (43) .

11. Device according to claim 10, characterized in that the wing (35) is attached to the arm (42) by means of two elastic blades (38), the fulcrum (PI) of a first of said blades on the arm (42) being adjacent to a free end of said arm, while the fulcrum (P2) of the other blade is located between the pivot (43) and the fulcrum (PI) of the first blade .