Nut punching apparatus

Abstract

A nut punching apparatus has a striking punch (1), a caulking die (2), a nut feeding guide (10) having a punch passage (11) and a nut delivery opening (12) perpendicular to the passage, and a driving means (14) moving the guide along the punch. The nut ‘N’ fed through the opening is pushed into a transfer zone located ahead the punch (1) while the guide (10) is at its foremost position. This guide is retracted to its rearmost position to allow the punch to cooperate with the die (2) to punch the nut ‘N’ onto a metal plate ‘W’. The apparatus has a positioning pin (20) through the punch so that its fore end portion reciprocates taking a foraward position ahead the punch and a retracted position. The pin (20) penetrates a threaded bore of the nut ‘N’ at the transfer zone, such that the projected fore end portion of the pin (20) passing through the nut ‘N’ engages with a positioning aperture (30) formed in the metal plate ‘W’.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a nut punching apparatus for use to strike the self-piercing nuts or the clinch nuts to a metal plate workpiece, so as to fix them thereon.

BACKGROUND OF THE INVENTION

[0002] Heretofore, every workpiece such as a metal plate, panel or sheet has been positioned by abutting its edge against a stopper or the like when punching the self-piercing nuts or the clinch nuts to be attached to said workpiece. This manner of positioning the workpieces may be suited to a case wherein a considerable number of them of the same shape and dimentsion are manufactured sequentially. However, intricate and time-spending operations have adversely been needed if many small lots of various kinds of workpieces had to be handled by frequently adjusting arrangement of relevant members in the apparatus.

SUMMARY OF THE INVENTION

[0003] An object of the present invention made in view of this drawback in the prior art is therefore to provide a novel type of nut punching apparatus that can operate smoothly and quickly to accurately position every nut on any desired portion of the workpiece, to which the nut has to be struck and fixed.

[0004] In order to achieve this object, the apparatus of the invention comprises a striking punch for thrusting a nut onto a metal plate, a caulking die facing the punch through the metal plate, a nut feeding guide having a punch passage and a nut delivery opening, the passage accommodating the punch to be slidable therein, the opening extending perpendicular to the passage, and a driving means for moving the nut feeding guide fore and aft along the punch longitudinally thereof. These members are combined together such that the nut having advanced through the delivery opening will be pushed into a transfer zone located ahead the fore end of the striking punch while the nut feeding guide is at its foremost position, and such that the nut feeding guide will be retracted to its rearmost position so as to allow the striking punch to cooperate with the caulking die to punch the nut onto the metal plate and to thereby attach it thereon. Further, the apparatus characteristically comprises a positioning pin that extends through the striking punch along an axis thereof so that a fore end portion of the pin reciprocates between its projected position ahead the fore end of the punch and its retracted position behind this fore end, such that the pin penetrates a threaded bore of the nut which will have arrived at the transfer zone ahead the punch, whereby the projected fore end portion of the pin passing through the nut is brought into engagement with a positioning aperture previously formed in the metal plate at its portion to which the nut will subsequently be punched and attached.

[0005] Preferably, the positioning pin may be held in a bore that is formed through the striking punch, and a pneumatic cylinder may be disposed in a basal end of the punch so as to drive the pin to retractably project its fore end portion beyond the fore end of the punch.

[0006] Also preferably, a pair of resilient pawls facing one another may be disposed on opposite lateral sides of the punch fore end so that the nut having arrived at the transfer zone will be gripped with these pawls.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a front elevation of a nut punching apparatus that is provided in the present invention and shown in its vertical cross section, wherein nuts are being fed towards a transfer zone;

[0008] FIG. 2 is a left side elevation of the apparatus shown in FIG. 1;

[0009] FIG. 3 is another front elevation of the apparatus shown in its status ready for the striking of the nut;

[0010] FIG. 4 is a left side elevation of the apparatus shown in FIG. 3;

[0011] FIG. 5 is a further front elevation of the apparatus shown in its status when positioning the nut; and

[0012] FIG. 6 is a still further front elevation of the apparatus shown in its status when punching the nut.

THE PREFERRED EMBODIMENTS OF THE INVENTION

[0013] Now some embodiments of the present invention will be described, referring to the drawings.

[0014] FIGS. 1 and 2 show the invention embodied in a nut punching apparatus that comprises a striking punch 1 and a caulking die 2 disposed to face the punch. In use of the apparatus, a workpiece ‘W’, i.e., a metal plate will intervene between the punch 1 and die 2, which are designed to sequentially punch self-piercing nuts or clinch nuts (hereinafter referred to simply as ‘nuts’) onto the workpiece ‘W’.

[0015] The striking punch 1 has a basal end fixed on a back plate 4 by means of a punch holder 3. The back plate 4 is secured to a base of a pressing machine (not shown) so that the punch 1 has an axis extending vertically to have its fore end portion located upwards. A pair of resilient pawls 5 and 5 (see FIGS. 2 and 4) facing one another are disposed on opposite lateral sides of a fore end of the striking punch 1. Each pawl 5 is a leaf spring connected by a screw, not shown, to the side of said punch side. In operation, a preceding one of the nuts ‘N’ will arrive at a transfer zone that is located ahead the punch fore end so as to be gripped by and between the resilient pawls 5. A stopper 6 defining an outer or downstream boundary for the transfer zone will serve to cause each nut to take its accurate position in said zone.

[0016] The caulking die 2 facing the punch 1 is mounted on a press ram (not shown) in the pressing machine. This die 2 located above the pressing punch stands precisely in an axial alignment therewith. In operation, the press ram will drive and carry the caulking die 2 in axial direction towards and away from the striking punch 1.

[0017] A nut feeding guide 10 is operatively combined with the striking punch 1 so as to slide relative thereto in axial direction thereof. A punch passage 11, that is a through-hole formed in the guide 10, will allow the punch to slide in axial direction. A nut delivery opening 12 formed also in the nut feeding guide 10 extends perpendicularly to the punch passage 11. A flexible hose 13 is connected to the delivery opening 12 so that the nuts ‘N’ are successively supplied towards the punch. In detail, the nuts will be sent one after another to the transfer zone located ahead the punch's 1 fore end which is temporarily at its position enclosed in the passage 11.

[0018] A pneumatic cylinder 14 fixed on the back plate 4 will drive the nut feeding guide 10 along the striking punch 1. A piston rod 15 of the double-action cylinder 14 extends in parallel with the punch and has en end secured to the feeding guide 10. Thus, this guide will move fore and aft (viz., up and down in the drawings) along the punch 1 and in unison with the piston rod 15. At a raised position of the feeding guide 10 as shown in FIGS. 1 and 2, the nuts ‘N’ advancing through the delivery opening 12 will be delivered one by one to the transfer zone that is then located ahead the punch fore end but retracted in the punch passage 11.

[0019] The striking punch 1 included in the nut punching apparatus of the invention does further comprise a positioning pin 20. This pin is able to reciprocate along the axis of the punch so that its fore end portion 20a can be projected forwards beyond or retracted backwards behind the fore end of striking punch 1. In detail, an axial bore 21 accommodates therein the positioning pin 20 to slide in axial direction. A basal end 20b of such a pin is connected to a piston 23 of a pneumatic cylinder 22 that is disposed in the basal end portion of the punch. A compression spring 24 fitted in the pneumatic cylinder 22 always urges the fore end portion 20a of the positioning pin 20 to sink and descend into the axial bore 21. However, with a compressed air being introduced into the cylinder through an air passage 25, the piston 23 will be forced upwards and forwards to lift the positioning pin 20. Consequently, its fore end portion 20a will protrude beyond the fore end of the striking punch 1, against elastic force of the spring 24.

[0020] In use, the nut punching apparatus of the describe structure will operate as follows. FIGS. 1 and 2 shows the nut feeding guide 10 at its raised position wherein the preceding one of the nuts ‘N’ being successively fed through the hose 13 has just moved into the transfer zone above the punch's fore end. The preceding nut ‘N’ thus discharged from the nut delivery opening 12 to said zone located inside the passage 11 is gripped with the pair of pawls 2 also located inside this passage. In this state, the fore end portion 20a of the positioning pin 20 is at its retracted position behind the fore end of the striking punch 1, lest the nut ‘N’ should be hindered from advancing smoothly.

[0021] Next, the nut feeding guide 10 will descend as seen in FIGS. 3 and 4, being driven by the one or main pneumatic cylinder 14. Simultaneously with this motion, a compressed air will be charged to the other or supplementary pneumatic cylinder 22 to lift the positioning pin 20 against the compression spring 24. In this state ready for punching the nut, the fore end portion 20a of the pin is at its position extended above the fore end of the striking punch 1. This means that the said end portion 20a protrudes up and out through the threaded bore of nut ‘N’ being held in place by the stopper 6 and pawls 5. On the other hand, a positioning aperture 30 has previously been formed in the workpiece ‘W’ at its portion to which the nut ‘N’ has to be attached.

[0022] The workpiece will then be placed between the caulking die 2 and the striking punch 1 that has been made ready for punching the nut, and its position will be adjusted by engaging the aperture 30 with the projected fore end 20a of the positioning pin 20 (see FIG. 5).

[0023] Subsequently, the caulking die 2 will descend as shown in FIG. 6 to cooperate with the punch 1 to forcibly grip between them the workpiece ‘W’, with a force enough for it to be bitten with the nut ‘N’. Upon fixation of the nut on the workpiece in this manner, the caulking die 2 will ascend to return both the positioning pin 20 and the nut feeding guide 10 to their home positions shown in FIG. 1.

[0024] In the illustrated embodiment, the striking punch 1 located below the caulking die 2 ascending and descending does stand still. A reversed arrangement may be employed instead, wherein the caulking die 2 is located below the punch 1 which will be driven up and down in this case.

[0025] It will now be apparent that in the invention the positioning pin incorporated in the striking punch penetrates the threaded bore of each nut that has been placed in the transfer zone above the punch for end. The fore end portion of such a pin will remain engaged with a positioning aperture formed in and at each desired point of the workpiece, during the subsequent punching process. Now, the positioning operation can be done more simply and quickly on one hand, and the nuts can be punched exactly into all the desired points in the workpiece on the other hand.

Claims

1. A nut punching apparatus comprising:

a striking punch for thrusting a nut onto a metal plate;

a caulking die facing the punch through the metal plate;

a nut feeding guide having a punch passage and a nut delivery opening;

the passage accommodating the punch to be slidable therein;

the opening extending perpendicular to the passage; and

a driving means for moving the nut feeding guide fore and aft along the punch longitudinally thereof, such that the nut having advanced through the delivery opening is pushed into a transfer zone located ahead a fore end of the striking punch while the nut feeding guide is at its foremost position, and

such that the nut feeding guide is retracted to its rearmost position so as to allow the striking punch to cooperate with the caulking die to punch the nut onto the metal plate,

the apparatus further comprising a positioning pin that extends through the striking punch along an axis thereof so that a fore end portion of the pin reciprocates between its projected position ahead the fore end of the punch and its retracted position behind this fore end, such that the pin penetrates a threaded bore of the nut which has arrived at the transfer zone ahead the punch,

whereby the projected fore end portion of the positioning pin passing through the nut is brought into engagement with a positioning aperture previously formed in the metal plate at its portion to which the nut is to be punched.

2. A nut punching apparatus as defined in

claim 1, wherein the positioning pin is held in a bore that is formed through the striking punch, and a pneumatic cylinder is disposed in a basal end of the punch so as to drive the pin to retractably project its fore end portion beyond the fore end of the punch.

3. A nut punching apparatus as defined in

claim 1 or

2, wherein a pair of resilient pawls facing one another are disposed on opposite lateral sides of the fore end of the punch so that the nut having arrived at the transfer zone is gripped with these pawls.