DE2819226A1 - Screwdriver attachment for drill - has coiled spring of slip clutch connected at one end to external sliding cap - Google Patents

Abstract

The screwdriver attachment for use on hand drill chucks is fitted with a wound spring slip clutch. The spring is attached on a cylinder connected with the drive shaft. The cylinder has a slightly smaller dia. than the internal dia. of the spring when relaxed. At the same time the cylinder is seated rotatably on the tube and has projections for similar recesses on the slidable element. At the start of the screwing operation the wound spring tightens on the circumference of the cylinder, which transfers the torque onto the screwdriver via the ball click stop device. When the pre set torque is exceeded, the balls leave the projections and shift the axially sliding element.

Description

Screw coupling with torque cut-off

The invention is as a YorsaZzkupplung for electr. Hand drills intended for screwing in screws.

The clutch is constructed similarly to that in the laid-open specification 26 24 232 named version, but with a significantly improved resetting the released clutch.

The clutch disconnects when an adjustable rotational ion is reached the output part of the drive. To reset the released clutch, the outer cap axially displaced.

The clutch essentially consists of a wrap spring clutch, which is opened via a spring-loaded ball catch depending on the component. As a connecting and control part is the outer cap.

The wrap spring 3 is firmly connected to the old of the drive shaft Cylinder 2 stored with preload. The cylinder 4 is slightly smaller in diameter than the inner diameter of the relaxed wrap spring and rotatable on the profile tube 8 stored. The cylinder 4 carries several arcuate widened on its end face Calottes, corresponding depressions are located on the sliding piece 5.

In the example of Figure 1, the outer cap 1 ii is coupled State pushed forward, towards the tip, this is where the resilient webs are 9 of the cap type of their fine teeth 11 with bias on the fine teeth 12 of the Cylinder 4 pushed.

The resilient webs 10 slide over bevels onto the sliding piece 5.

The bent free end 13 of the wrap spring engages in a slot the outer cap and is so fixed with respect to the cylinder 4. About the Stellautter 7 and the compression spring is preloaded for the required torque.

In the embodiment of Figure 2, the outer cap 14 is in the activated, engaged state shifted backwards, away from the tip. this takes effect the fine teeth 11 of the cap in lie fine teeth 12 of the cylinder 4 as ii first Example.

At the beginning of a screwing process, the wrap spring is on the circumference of the cylinder 4 is drawn, which then applies the torque via the ball engagement to the Screwdriver bit transfers.

When the set limit value is reached, the balls leave the Calottes and thereby move the sliding piece 5 axially. In the example according to Figure 1 The resilient webs 10 slide from the circumference of the sliding piece 5. If the Balls fall into the next calottes, the sliding piece moves back and takes the cap 1 back in the first example, the resilient webs 9 and the fine teeth 11 come out of engagement with the cylinder 4. The cap 1 is thereby freely rotatable and the wrap spring snaps into the relaxed, open position.

In the example of Figure 2, the cap 14 is exceeded when the The set torque is taken along by the sliding piece 5 moving forward and is thereby already released in the middle between the notches. As a result of delayed opening of the wrap spring and the narrow webs between the Here, too, the spheres reach the next detent position.

The length of the calottes is dimensioned so that the wrap spring also has opened at high speed before the balls reach the next rise. Three balls are used so that each ball can use some of the force of the compression spring beauf is hit, so that only rolling processes between parts 4 and 5 and the balls occur and sliding friction is avoided.

Claims (3)

Claims 9 screw coupling with torque cut-off for screwing in of screws with adjustable torque, especially as an attachment for Hand drills, the drive hub being connected to a wrap spring, whose unloaded diameter is larger than the diameter of the output hub, characterized 7 that the free end of a loop spring (13) with an outer Cap is in engagement and this by axial displacement with a driven part, preferably the cylinder (4), can be brought into engagement so that the drive rotation leads to the closing of the wrap spring and thus couples the two cylinders (2) and (3). 2. Screw coupling according to claim 1, characterized in that resilient webs (10) are located on the cap (1). the one with the activation of the clutch be pushed onto the circumference of the sliding piece (5) and when it snaps into place the locking balls slide off the circumference of the sliding piece and when they fall back in the locking balls are pushed back by this with the cap, so that the cap is freely rotatable 3. Screw coupling according to claim 1, characterized in that a collar (15) arranged in front of the sliding piece (5) is located on the cap (14) so that the cap disengages from the recesses as the balls rise the cylinder (4) is moved and is thus freely rotatable.