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Title:
DEVICE FOR MECHANICALLY ARRANGING A FIXING ELEMENT SUCH AS A BOLT OR A SCREW
Document Type and Number:
WIPO Patent Application WO/2002/072314
Kind Code:
A1
Abstract:
Device for mechanically arranging a fixing element, such as screws or bolts, which device comprises a housing (1), a motor (M), a screw bit which is driven by this motor via a displaceable spindle (10) and which is displaceable form a position retracted into the housing to an operating position at the end of the housing and vice versa, wherein the housing is provided with a distance sensor (19) and a displacing member (17, 18) co-acting therewith which is coupled to the spindle (10) and biased by a spring element (13) in the direction away from the distance sensor (19), such that when a determined torque is reached the displacing member (17, 18) moves in the direction of the sensor, which at a determined minimum distance generates a signal to stop the drive motor (M).

Inventors:
PEETERS MARC (BE)
Application Number:
PCT/BE2002/000034
Publication Date:
September 19, 2002
Filing Date:
March 13, 2002
Export Citation:
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Assignee:
COBHRA IND BVBA (BE)
PEETERS MARC (BE)
International Classes:
B23P19/06; B25B23/14; (IPC1-7): B25B23/14; B23P19/06
Foreign References:
US4208555A1980-06-17
US5156221A1992-10-20
US3906819A1975-09-23
US5738177A1998-04-14
GB2271522A1994-04-20
Other References:
PATENT ABSTRACTS OF JAPAN vol. 012, no. 419 (M - 760) 8 November 1988 (1988-11-08)
Attorney, Agent or Firm:
ARNOLD & SIEDSMA (Petrus, Nicolaas Luiza-Marialei 8 Antwerpen, NL)
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Claims:
CLAIMS
1. Device for mechanically arranging a fixing element, such as screws or bolts, which device comprises a housing, a motor, particularly an electric motor, accommodated in the housing, a screw bit which is driven by this motor via a displaceable spindle and which is displaceable from a position retracted into the housing to an operating position at the end of the housing and vice versa, and a guide member leading to this housing end for feeding a fixing element to this housing end to a position in front of the retracted screw bit, characterized in that the housing is provided with a distance sensor and a displacing member cacting therewith which is coupled to the spindle and biased by a spring element in the direction away from the distance sensor, such that during raising of the torque the displacing member moves in the direction of the sensor, which at each distance generates a related signal, said signal is compared with a predetermined value by a comparator in an electric circuit, in order to stop the drive motor.
2. Device as claimed in claim 1, characterized in that the spring element is a coil spring.
3. Device as claimed in claim 1 or 2, characterized in that the displaceable spindle is hollow for receiving the motor shaft, the shaft is provided with a claw coupling which is in engagement with the spindle, which claw coupling spreads apart at the determined torque, wherein the displacing member is fixed onto the part of the claw coupling which is shiftable but free rotatably connected to the spindle.
4. Device as claimed in claim 3, characterized in that ball bodies are arranged between the spreadable parts of the claw coupling.
Description:
DEVICE FOR MECHANICALLY ARRANGING A FIXING ELEMENT SUCH AS A BOLT OR A SCREW The invention relates to a device for mechanically arranging a fixing element, such as screws or bolts, which device comprises a housing, a motor, particularly an electric motor, accommodated in the housing, a screw bit which is driven by this motor via a displaceable spindle and which is displaceable from a position retracted into the housing to an operating position at the end of the housing and vice versa, and a guide member leading to this housing end for feeding a fixing element to this housing end to a position in front of the retracted screw bit.

Such a device is frequently used commercially for electrical or pneumatic insertion of connecting elements in industrial applications in order to facilitate manual arrangement. Such a device can be operated by hand, but is fully weight-compensated, while the torque is supplied by the drive motor. The safety of these devices is ensured in that the motor must cut out when the drive torque is exceeded as a result of a raising resistance while thightening the fixing element.

The known devices have the drawback that setting of the maximum drive torque, exceeding of which must result in cut-out, is difficult to adjust since a spring usually determines the bias of the override coupling. In order to adjust the biasing force of the spring a part of the device has to be disassembled and then reassembled.

The invention has for its object to provide a device wherein setting proceeds in considerably simpler manner, wherein the spring tension plays no part.

The invention provides for this purpose a device which is distinguished in that the housing is provided

with a distance sensor and a displacing member co-acting therewith which is coupled to the spindle and biased by a spring element in the direction away from the distance sensor, such that during raising of the torque the displacing member moves in the direction of the sensor, which at each distance generates a related signal, said signal is compared with a predetermined value by a comparator in an electric circuit, in order to stop the drive motor.

Owing to the co-action of a displacing member and a distance sensor the moment the drive motor cuts out is determined by the distance between the displacing member and the distance sensor. The biasing spring for holding under bias the starting position of the distance member plays no part here. Determining of the distance can be readily adjusted by the vibration of the distance sensor, which can be determined electronically. The distance sensor can be embodied as inductive sensor which can be analog as well as digital.

Above mentioned and other features of the invention will be further elucidated in the figure description hereinbelow of an embodiment.

In the drawing: Figure 1 shows a perspective view of a part of the screwdriver provided with a handle and a feed guide for the fixing elements and the rotatable head thereof.

Figures 2 and 3 show in each case a perspective view of a part of the distance sensor and the displacing member applied in the device of figure 1, respectively in a starting position and a cut-out or restposition.

The device according to the invention is provided in figure 1 with a housing 1 which also serves as handle which is connected at the top end 2 to a weight- compensating means or otherwise (not shown), this such that the drive motor (not shown) accommodated in housing

1 can (pneumatically or electrically) drive a spindle which is further elucidated below. Arranged on the other end 3 of the housing is a bit head 4 onto which a guide member 5 for supplying fixing element B to the bit head is connected laterally. The shown screw element B enters the bit head 4 with a shank to the outside in the operative position and is set into rotation by a screw bit in the form of a hexagon or cross driven by the motor, and can thus be screwed into the parts to be fixed.

It is assumed known how such a device operates and a further description hereof is not given, although it is noted that the interior can be embodied in many ways.

Figures 2 and 3 show a motor spindle 10 which is deemed to be connected to the motor M, indicated schematically, as stated above. The screw spindle is embodied at the upper end with a sleeve 11 which is connected slidably but non-rotatably to spindle 10, for instance due to a non-round form of the screw spindle.

Arranged for this purpose is a support 12 which here consists of two nuts rotated onto a screw thread of screw spindle 10 and fixed against each other, which support serves to support a coil spring 13. This latter presses against a displacing member 14, here in the form of the one part of a claw coupling generally designated with 15, wherein the other part 16 of claw coupling 15 is fixed to screw spindle 10.

The part 14 of claw coupling 15 is provided with a ring 17 which is mounted non-displaceably in axial direction but rotatably with respect to the part 14 of claw coupling 15. Ring 17 is provided with a protrusion 18 which serves as sensor element for the sensor system of part 14, ring 17 and protrusion 18 in relation to the motor housing. Arranged in the motor housing is a distance sensor 19 which can be embodied in random

manner and can be for example mounted on the inside of housing 1. The distance sensor 19 is connected to a PLC, provided with a comparator A manually actuatable member gives a desired signal to the comparator, wherein the signal, to generating a control signal to stop the motor M when both signals are equal.

The operation of the device of figures 2 and 3 is as follows.

When the motor is energized the motor shaft 10 will be set into rotation with co-displacement of claw coupling 15, spring 13, support 12 and sleeve 11 which is connected to the bit.

Starting from the position of figure 2, the claw coupling 15 is closed under the influence of the pressure of spring 13. When a determined drive torque is reached, the two parts 14,16 of claw coupling 15 will undergo a small rotation relative to each other, whereby the parts 14,16 claw coupling will begin to spread apart as a result of the inclining surfaces 20,21, this such that the part 14 is displaced upward in figures 2 and 3 counter to the spring action of spring 13. At a determined distance between end surface 22 of distance sensor 19 and the surface of protrusion 18 directed toward it, sensor 19 will respond and then generate a signal to cause the drive motor to cut out.

In order to set the desired torque at which the motor must be cut out, it is sufficient to adjust the sensitivity of distance sensor 19, and thereby the related distance between surfaces 22 and 23 determining the value of the cut-off torque.

In order to facilitate spreading of parts 14,16 of claw coupling 15, a ball 24 is placed between the inclining surfaces 20,21 to reduce friction.

The invention is not limited to the above described embodiment.