SE1451457A1 - Power screw driver with vacuum screw pick-up feature - Google Patents

Description

P20-l47l3-l4ll27 pick-up, comprising a housing with a nose piece connected to a vacuum source, a drive spindle, a screw bit connected to the drive spindle, and a tubular screw guiding nozzle mounted on the nose piece and comprising an inner shoulder for supporting a screw in a screw installing start position. An adjustable mounting device is provided between the screw guiding nozzle and the nose piece for axial adjustment and setting of the screw guiding nozzle to thereby obtain a correct screw supporting position of said shoulder in said screw installing start position.

The power screw driver according to the invention may be easily and reliably adjusted and adapted to screw bits of different lengths, without the requirement of any costly machining operation.

Further characteristics and advantages of the invention will appear from the following specification and claims.

SHORT DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described below in detail in with reference to the accompanying drawings, of which: Fig. 1 shows a side view of a power screw driver according to the invention.

Fig. 2 shows a longitudinal section through the front end of the power screw driver in Fig. 1.

Fig. 3 shows on a larger scale a longitudinal section through the front end of the nose piece of the power screw driver in Figs. l and 2 and illustrates a non-adjusted screw guiding nozzle.

DETAILED DESCRIPTION OF THE SHOWN EMODIMENT OF THE INVENTION The power screw driver shown in Fig. l comprises features for vacuum pick-up of screws for assembly operations and includes a P20-14713-141127 housing 10 provided with a nose piece 11 having a connection 12 for connection to a vacuum source.

The housing 10 supports a rotation motor 15 drivingly coupled to a hollow drive spindle 16. A screw bit 18 for engaging a screw 14 to be tightened extends into the drive spindle 16 and is connected thereto via a coupling 19.

The nose piece 11 is telescopic and comprises two parts, namely a fixed part 11a and a forward movable part 11b, wherein the movable part is biased by a spring 21 towards a forward rest position. At its front end the nose piece 11 is provided with a tubular screw bit guiding nozzle 22 which is connected to the nose piece part 11 via a thread connection 24. To that end the screw guiding nozzle 22 is provided with an outer thread 25 mating with an inner thread 26 in the nose piece 11. See Fig. 2.

By this thread connection 24 the screw guiding nozzle 22 is axially adjustable relative to the nose piece 11 as well as to the screw bit 18, and a lock nut 27 on the nozzle 22 is provided for locking the nozzle 22 in a desired axial position relative to the nose piece 11. The screw bit is provided as an exchangeable part and may be of different lengths and individually adapted to the type of screw chosen for the actual assembly operation. The difference in length requires adjustments of the axial position of the nozzle 22 to get a proper engagement between the screw and the screw bit.

The screw guiding nozzle 22 has a forward guide bore 30 adapted by its diameter to the head of the screw 14 to be used, and a rear bore 31 with a smaller diameter, though big enough to let air pass the screw bit 18 and sustain the vacuum effect on the screw 14. At the rear end of the forward guide bore 30 there is an annular shoulder 33 on which the head of the screw 14 shall rest in the start position of the screw mounting operation. This rest position of the screw 14 is crucial for guaranteeing a straight orientation of the screw 14 and a correct engagement of the screw bit 18. In this position it is important that the P20-14713-141127 forward end of the screw bit 18 is substantially flush with the shoulder 33. This position is illustrated in Fig. 2. The screw bit is removably connected to the drive spindle 16 via torque transferring coupling. Since this coupling is not critical for the embodiments of the invention and may be of any suitable type it is not described in further detail.

In Fig. 2 the screw driver is illustrated in a position wherein a screw 14 has been picked up via the sub-atmospheric pressure created in the nose piece 11 and the screw guiding nozzle 22 by a connected vacuum source, wherein the head of the screw 14 is brought into a rest position against the shoulder 33 in the screw guiding nozzle 22 and the forward end of the screw bit 18 is in an engagement position with the screw head. To guarantee accurate relative positions of the screw supporting shoulder 33 and the screw bit 18 the axial position of the screw guiding nozzle 22 has to be carefully adjusted and set. This is accomplished by means of the thread connection 24 between the nose piece 11 and the screw guiding nozzle 22, and when the accurate position is obtained the screw guiding nozzle 22 is locked by tightening the lock nut 27 against the nose piece 11.

Such an individual adjustment and setting of the relative positions of the screw guiding nozzle 22 and the nose piece 11 is necessary since the length of the screw bit 18 may vary between different individual screw bits. So, by providing an adjustable connection between the screw guiding nozzle and the nose piece 11 it is possible to adjust axially the screw guiding nozzle 22 to get the shoulder 33 in a correct position relative to the screw bit 18 without any costly machining operations which has been necessary at prior art screw drivers of this type.

In Fig. 3 there is illustrated an erroneous position of the screw guiding nozzle 22 wherein the screw position defining position of the inner shoulder 33 is located far off from the screw bit 18 which means that the screw head is resting against P20-14713-141127 the shoulder 33 and that a correct engagement between the screw 14 and the screw bit 18 may still be obtained, but an unnecessary long axial travel of the screw driver would be necessary to push back the front end section 11b of the nose piece 11 to bring the screw bit 18 into engagement with screw head.

An opposite situation, on the other hand, where the screw bit 18 extends past the shoulder 33 in the start position such that the screw 14 cannot reach and get a proper support by the shoulder 33 would be disastrous for the screw installing operation, because the screw 14 would not get a proper straight position in the screw guiding nozzle 22 and a proper screw head engagement by the screw bit 18 would be impossible.

It is to be understood however, that the embodiments of the invention are not limited to the above described example but may be freely varied within the scope of the invention as defined in the claims.

Claims (3)

P20-14713-141127 Claims

1. A power screw driver adapted for vacuum operated screw pick-up, comprising a housing (10) with a nose piece (11) connected to a vacuum source, a drive spindle (16), a screw bit (18) connected to the drive spindle (16), and a tubular screw guiding nozzle (22) mounted on the nose piece (11) and comprising an inner shoulder (33) for supporting a screw (14) in a screw installing start position, c h a r a c t e r i z e d in that an adjustable mounting device (24) is provided between the screw guiding nozzle (22) and the nose piece (11) for axial adjustment and setting of the screw guiding nozzle (22) to thereby obtain a correct screw supporting position of said shoulder (33) in relation to the actually attached screw bit (18) in said screw installing start position.

2. Power screw driver according to claim 1, wherein said adjustable mounting device (24) comprises matching threads (25,26) on the screw guiding nozzle (22) and the nose piece (11), respectively.

3. Power screw driver according to claim 2, wherein said matching threads (25,26) comprises an outer thread (25) on the screw guiding nozzle (22) and an inner thread (26) on the nose piece (11), and said outer thread (25) on the screw guiding nozzle (22) carries a lock nut (27) to be tightened against the nose piece (11) to thereby lock the screw guiding nozzle (22) in a desired axial position.