DE3941469A1 - WORKING METHOD FOR PRODUCING A CENTERING RING IN THE CLAMP LEG OF A U-SHAPED T-NUT - Google Patents

Description

The invention relates to a method of manufacture a centering ring in the clamping leg of a U-shaped sheet mother according to the preamble of claim 1.

The purpose of this centering ring is to use the metal nut when plugging onto the edge of a carrier plate for loading fixing hole. Since the carrier plates - as with for example the body panels in motor vehicle construction - for protection are often provided with a protective layer against corrosion, care must be taken that this protective layer by the Center ring protruding diagonally to the thread leg being scratched. Therefore the centering ring must be as soft as possible be designed to be resilient so that it is attached the sheet metal nut can spring back into the clamping leg level.

But because a punched centering ring because of the sharp past shear edges not in its out can spring back, one has gone over to rings a so-called free around the outer edge of the centering ring to provide a smooth immersion in to enable the recess (cf. OE-PS 3 63 737 - US 42 43 086). Now that the free cut is a certain cut width requires, the sheet metal nut must be correspondingly wider be interpreted, which inevitably leads to material consumption increases. It can also happen in rough assembly operations happen that with awkward introduction of the sheet metal screw be the screw tip next to the centering ring in the free cut and got caught there.

The object of the invention is therefore, the centering ring from the clamp leg to work out that on the free cut can be dispensed with and still a sufficiently wide Air gap remains between the ring and recess so that the Centering ring easily in the recess of the clamping leg can spring back.  

To solve the problem is that specified in claim 1 Working method proposed, on the one hand by the dome-shaped deep drawing in the 2nd stage of work and on the other hand by pushing the kinked Ver tie bar in the last stage after the end punch the calotte is reached that the centering ring small on all sides, but sufficient to spring back has the air gap to the recess. It also results thereby the further advantage that the screw tip no longer in the free when screwing into the sheet metal nut cutting gap can occur.

In the drawing is the interaction of the punching and Bending tools at the individual work stages as well its effect on the sheet metal strip to be processed shown and will be explained in more detail below. It shows

Fig. 1 shows the sequence of movement of the processing tools in the first processing stage,

Fig. 2 shows the associated sheet-metal strip segment after punching out of the full plate in top view,

Fig. 3 shows the movement sequence during the second working step,

Fig. 4 shows the sheet metal strip segment after deep drawing of the full plate,

Fig. 5 shows the sequence of movements in the third stage of operation,

Fig. 6 shows the sheet metal strip segment after punching of the inner plate of the centering ring,

Fig. 7, the sequence of movements at the fourth stage and

Fig. 8 the sheet metal strip cut after pressing the connecting web straight.

In the first stage ( Fig. 1) from a sheet metal strip 1 by means of a stamp 2, a solid plate 3 accordingly the outer edge of the later centering ring 15 punched out together with a connecting web 4 and in an underlying die 5 to a position just below that Sheet metal strip 1 depressed.

In the second stage ( Fig. 3) is then punched out the full plate 3 by a punch 6 with a semi-spherical tip 7 in a die 8 with a corresponding recess 19 deep-drawn, the edge 9 of the full plate 3 from the die edge 10 in the low level reached in the first work stage is supported. Here, the edge 9 of the solid plate 3 is pulled somewhat towards the center, so that a small gap 12 forms with the inner edge 11 of the cutout in the metal strip 1 .

In the third stage ( FIG. 5), the dome-shaped inner plate 14 is punched out by a further punch 13 against a die 16 , which supports the centering ring 15 remaining in the low position.

Finally, in the fourth and final stage ( Fig. 7) by the interaction of a stamp 17 and a die 18, the centering ring 15 from the web 4 from ge in the desired oblique position for later use.

In this case, the connecting web 4, which is somewhat stretched in the first working stage when it is bent, is stretched again when it is pushed up, and the centering ring 15 is simultaneously pressed toward the center of the recess. As a result, the centering ring 15 has a small gap 12 on all sides, but sufficient to spring back into the recess.

In principle it would of course be possible and also practicable to push up the ridge 4 immediately after the deep-drawing of the cap 14, that is, between Figs. 3 and FIG. 5 or as a separate operation between Fig. 5 and Fig. 7, but may be in a particular representation of this Steps to be dispensed with, since it is only important for the success desired according to the invention that the web is pushed up and the centering ring or the deep-drawn solid plate can stretch.

On the presentation of the further work stages for embossing of the thread and to form the U-shaped sheet metal nut with Clamping and threaded legs were omitted in the drawing tet, because these work stages are generally known and with the inventive production of the centering ring nothing have to do.

Claims (1)

A process for producing a centering ring in the clamping leg of a U-shaped sheet metal nut by punching out a round solid plate and a likewise round inner plate and then obliquely bending the centering ring thus produced, the punched centering ring remaining connected to the clamping leg via a narrow web, characterized in that the punched-out solid plate ( 3 ) is first pressed down to just below the sheet metal strip ( 1 ) and deep-drawn before the punching out of the centering ring ( 15 ), and then the bent web ( 4 ) is pressed up again into the sheet metal strip plane, the gap ( 12 ) which during deep-drawing of the calotte (14) between the outside of the solid plate (3) and the web (4) circumferentially opposite inner edge (11) plate of the sector cut-out of the whole (3) is greater than the extension of the centering ring (15) when pushing the bent web ( 4 ) into the sheet metal strip level.