EP0041710B1 - Method of manufacturing a hollow needle for label attachment - Google Patents

Abstract

A method of manufacturing hollow needles from round metal blanks in order to form a needle which has an inner front portion with a front end tapering to a point and a rear portion having a larger diameter than the front portion and forming a mounting shank, comprising forming a longitudinally extending needle guide to the needle such that the guide is open at the rear end of the mounting shank and tapers from a substantially uniform depth along a major portion of its length to a minimum depth adjacent the tip. The channel is of a shape to receive substantially cylindrical cross pins having an appended piece of filament which form a part of fasteners for tags, buttons and similar items to be attached to carrier materials such as textiles. The method is carried out by the use of a disc-shaped miller cutter which has U-shaped convex teeth for milling the central area of the channel in side tooth portions for milling shoulders on each side of the channel which are of lesser depth than the channel. The side tooth portions are employed to mill inclined V-recessed surfaces on each side of the central channel. In accordance with the inventive method after the channel is milled it goes to extend from the rear end along the inner front portion and taper to substantially a minimum depth at a spaced location from the tip, a stamping tool is used to engage into the inclined surfaces formed by the side teeth so that these surfaces are pressed inwardly to close a major portion of the length of the channel but without closing a release portion adjacent the tip of the needle which is less substantially equal to the width of the channel.

Description

The invention relates to a method for producing a hollow needle made of round steel provided at the rear end with a thicker mounting shank, which has a guide channel which is open at the front end at the rear end of the mounting shank and runs radially in front of the needle tip for at least approximately cylindrical cross pins of fasteners provided with a thread Has labels, buttons or the like, which are to be attached to textiles or similar substrates, the guide channel being provided with a longitudinal slot, the width of which is smaller than the width of the guide channel.

Such hollow needles, the manufacture of which is the subject of the present invention, are used in devices for attaching fasteners for buttons, labels or the like to textiles or similar substrates. The fasteners used are made of plastic and are arranged detachably on a common strand. They each consist of a head part and a thread-shaped connecting piece protruding therefrom, in the middle or in the end area penetrated by a transverse pin. The hollow needle serves to pierce the carrier material to which the fastener is to be attached and to pass the cross pin through the carrier material. For this purpose, the device is provided with a piston which crosses a feed channel, pushes back and forth, which can be inserted from the rear end into the guide channel of the hollow needle, in order to in each case through the hollow needle the transverse pin inserted from the side into the guide channel of the hollow needle push.

In the manufacture of such hollow needles from round steel, the guide channel is produced according to the previously known methods in such a way that the needle blank, which is pre-turned with the needle tip and the assembly shaft, is provided with a concentric bore from the front side of the assembly shaft, which extends approximately to the point where the conical section of the needle tip begins. To do this, it is necessary to drill a center hole in the front of the mounting shaft. Afterwards, the end of the hole near the needle tip is milled by means of a disc milling cutter, the width of which is greater than the outer needle diameter and which is inserted into the material of the needle with radial feed so far, so that a hole in the outside of the needle Circular segment-shaped recess is formed, and after this process, the arcuate bore outlet is milled with another milling cutter that has a smaller diameter and a thickness that corresponds to the bore diameter. With a further side milling cutter, the thickness of which is smaller than the bore diameter, the longitudinal slot of the bore is then produced in a further operation.

If one disregards the additionally required deburring step, five steps are required for the creation of the guide channel in the conventional method alone.

It is also already known to produce hollow needles for such label fastening devices from an elongated piece-like material with lateral sections at the front end to form the tip, which are bent into a tube guiding the transverse pins in such a way that the longitudinal edges form the longitudinal slot, the tube at the rear End in side protrusions on the flat material, for fastening the hollow needle in a housing. In the case of hollow needles of this type, the rear mounting shaft is formed by a pointed plastic piece. These hollow needles bent out of sheet metal into a tube can be manufactured very cheaply, but they have the disadvantage that they do not have sufficient stability, especially in the area of their tip, so that they can be easily bent, or that their tip is hard materials that are pierced should break off or quickly become dull (DE-BZ No. 1805474). For this reason, hollow needles made of round steel are preferred in practice for such label fastening devices (US-A No. 2069879).

The invention is based on the object of specifying a method for producing hollow needles of the type mentioned at the outset from round steel, which, in particular, enables the axial guide channel of the hollow needle to be produced more simply and with fewer operations.

This object is achieved according to the invention in that, in order to produce the slotted guide channel, a U-shaped longitudinal groove is milled from the rear end of the shaft to approximately the needle section tapering to the tip by means of a disc cutter having a U-shaped cutting profile, which groove is formed in the mounting shaft in the outside of the radial area lying thinner in the needle cross-section than in the radial area lying within the needle cross-section and having step-like edge surfaces on both sides, and that the edges of the U-shaped longitudinal groove are then inward by means of an embossing tool, leaving a radial outlet slot located near the tip and having the width of the longitudinal groove be shaped.

This method not only eliminates drilling, which often results in the drill running or breaking, especially with small drill diameters, but also the milling of the guide channel outlet near the needle tip and the radial milling of the bore to achieve an outlet opening, and drilling also eliminates the need to drill a center hole on the front of the mounting shaft. It also prevents ring-shaped grooves in the guide channel arise that are inevitable when drilling and can be very annoying for the passage of the cross pins of the label holder to be attached.

It is advantageous if the peripheral edge sections of the U-shaped longitudinal groove are undercut in a V-shape in the region of the mounting shaft, because this makes the inward stamping of the peripheral edges easier and, above all, more uniform. If one provides that the edge edge sections of the U-shaped longitudinal groove in the assembly shaft have a greater radial distance from the needle axis both before and after the embossing process than the edge edge sections of the longitudinal groove in the needle area, the guide channel in the area of the assembly shaft has a greater radial distance Has expansion than in the needle area. This is particularly advantageous if the threads integrally molded onto the cross pins of the label fasteners in the vicinity of the cross pins are somewhat thicker than at a greater distance from the cross pin, so that these fasteners can be more easily inserted into or pushed through the guide channel of the hollow needle .

Further advantageous features of the invention are the subject of claims 4 and 5.

• Fig. 1 einen Axialschnitt durch eine Hohlnadel und teilweise einen Prägestempel,
• Fig. 2 einen Schnitt 11-11 der Fig. 1 mit einem ebenfalls im Schnitt dargestellten Fräserprofil,
• Fig. 3 einen Schnitt entlang der Schnittlinie 11-11 der Fig. 1 nach dem Prägevorgang mit geschnittenen Prägestempelprofil,
• Fig. 4 einen Längsschnitt durch eine andere Ausführungsform einer Hohlnadel mit einem anderen Prägestempel,
• Fig. 4a die Nadelspitze der Fig. 4 in Draufsicht,
• Fig. 5 einen Schnitt V-V in Fig. 4,
• Fig. 6 einen Schnitt V-V in Fig. 4 nach dem Einwärtsprägen der Längsnutkanten,
• Fig. 7 die fertige Hohlnadel gemäss Fig. 1 in Draufsicht,
• Fig. 8 einen Strang mit Etikettenbefestigern in Seitenansicht, und
• Fig. 9 eine Schnittansicht IX-IX aus Fig. 8.

The invention will now be explained in more detail with reference to the drawing. It shows:

• 1 is an axial section through a hollow needle and partially an embossing stamp,
• 2 shows a section 11-11 of FIG. 1 with a milling cutter profile also shown in section,
• 3 shows a section along the section line 11-11 of FIG. 1 after the embossing process with the embossing die profile cut,
• 4 shows a longitudinal section through another embodiment of a hollow needle with a different embossing die,
• 4a, the needle tip of FIG. 4 in plan view,
• 5 shows a section VV in Fig. 4,
• 6 shows a section VV in FIG. 4 after the inward embossing of the longitudinal groove edges,
• 7 shows the finished hollow needle according to FIG. 1 in plan view,
• Fig. 8 is a strand with label fasteners in side view, and
• FIG. 9 shows a sectional view IX-IX from FIG. 8.

The hollow needle 1 shown in Fig. 1 consists of a one-piece, turned round steel part, which is provided at the front end with a tapered tip 2 and at the rear end with an assembly shaft 3, the diameter of which is approximately twice as large as the diameter of the thinner front Needle part 4. Between the thinner needle part 4 and the mounting shaft 3 there is a fillet-like transition 5. To create an axial guide channel 10 ', first of all by means of a disk milling cutter 7, which has a U-shaped cutting profile 8 with V-shaped protruding cutting teeth 9 the rear end of the mounting shaft 3 ago milled a longitudinal groove 10, which radially ends in the vicinity of the tip 2 in an arc 11 corresponding to the circumferential curvature of the side milling cutter 7. When milling the longitudinal groove 10, the side milling cutter 7 dips with its U-shaped circumferential profile 8 so deeply into the material of the hollow needle 1 that the center of the semicircular profile 8 coincides with the longitudinal axis 11 of the hollow needle 1. This gives the longitudinal groove 10 the cross-sectional profile shown in FIG. 2, and two edge edges 12 and 13 undercut on both sides by V-shaped edge surfaces 12 'and 13' are formed over the length of the thicker mounting shaft, which lie outside the diameter range or outside the edge edges 14 of the thinner needle part 4. The lateral cutting teeth 9 are namely in this case arranged at a radial distance from the circumference of the U-shaped cutter profile 8, which is larger than the radius of the thinner needle part 4.

The edge edges 12 and 13 or 14 of the longitudinal groove 10 are embossed inward by means of an embossing die 15 which has approximately the width of the cutting profile of the lateral cutting teeth 9 of the side milling cutter 7 and which has stepped embossing surface sections 16 and 17, so that the one from FIG. 3 Obvious shape of a guide channel 10 'arises, which is characterized in that it has the shape of a slotted elongated hole in the area of the mounting shaft 3 and approximately the shape of an axially slotted bore in the area of the thin needle part. The axial extent of the embossing die 15 or the axial extent of the embossing surface section 16 is selected such that the edge edges 14 of the thinner needle part 4 are not embossed inward over their entire length, but from one point 18 to the transition 5, so that between the Place 18 and the outlet end 19 of the longitudinal groove 10, an outlet slot 23 remains, through which the transverse pins 20 pushed from the shaft end through the guide channel 10 'of the label fasteners 21 shown in FIG. 8 lead out of the hollow needle or from their guide channel 10' in a radial movement can be. In the section lying between the point 18 and the outlet end 19, the width of the longitudinal groove 10 worked in with the side milling cutter 7 thus remains, while in the region of the hollow needle 1 lying behind it, a guide channel 10 'is formed by the inward stamping of the peripheral edges 12, 13 and 14 an axial slot 22 is formed, the width of which is smaller than the width of the guide channel 10 'itself.

When this needle is used, the thread-like part 21 'of the label fastener to be fastened slides through the axial slot 22 when the associated transverse pin 20 is pushed through the guide channel 10'.

It is expedient to deburr the edge edges 14 at least in the area of the outlet slot 23 or by means of a cutting tool, e.g. a file to break.

So that there is no radially step-shaped shoulder when the edge edges 12, 13 and 14 are stamped inwards in the region of the transition 5, the transition 24 between the stamping surface section 17 and the stamping surface section 16 of the stamping stamp 15 arcuately or obliquely. The oval or slot-like cross-sectional shape of the section of the guide channel 10 'lying in the region of the mounting shaft 3 serves to facilitate the insertion of the transverse pins 20 into the rear section of the guide channel 10', in particular when - as is often the case in practice - the thread-like one Part 21 'of the label fastener 21 at the junction with the cross pin 20 is somewhat thicker than in the rest of the area. For the lateral insertion of the transverse pins 20 into the guide channel 10 ', a transverse groove 25 is provided at the rear end of the mounting shaft 3 of the hollow needle 1. In addition, in order to cut off the transverse pins 20 from the thread sections 21 ', which connect them with a strand 26, the rear end of the guide channel 10' can be provided with a cutting edge 28 by means of a frontal milling 27.

In the embodiment shown in FIGS. 4, 4a, 5 and 6, the same needle blank is used as in the embodiment described above.

In this case, however, a disk milling cutter 7 'is used to produce the longitudinal groove 10, which has the same cutting profile as the disk milling cutter 7, but in which the cutting teeth 9' projecting laterally in a V-shape have a smaller distance from the circumference of the U-shaped cutting profile 8 ', which is matched to the radius of the thinner needle part 4. The edge edges 14 ', which are produced with this milling cutter 7', therefore run through in one plane in the region of the mounting shaft 3. An embossing die 15 'is therefore used for embossing the edge edges 14' of the longitudinal groove 10, which has a non-offset (FIG. 4), continuously flat embossing surface 17 '. The longitudinal groove 10 produced with the milling cutter 7 'thus receives the cross-sectional shape shown in FIG. 5 with the edge edges 14' undercut in a V-shape in the region of the mounting shaft 3 '. After the edge edges 14 'have been stamped inwards by the stamping die 15', an at least approximately round guide channel 10/1 is formed which has the same cross-sectional shape over its entire length and has a longitudinal slot 22 '.

As a further difference from the embodiment of the hollow needle 1, the hollow needle 1 'has a radial, arc-shaped cutout 29 which is arranged in such a way that the longitudinal slot 22' and thus also the guide channel 10/1 at a point 18 'corresponding to the point 18 of the hollow needle 1 ends and opens into a radial outlet opening 23 'which extends between the point 18' and the outlet end 19 of the longitudinal groove 10. By means of this milling 29 it can be achieved that the transverse pins 20 of the label fasteners guided through the guide channel can emerge somewhat more easily from the hollow needle. However, this cutout 29 is not absolutely necessary. Without it, the hollow needle is at least cheaper to manufacture due to the omission of one operation. Otherwise, the manufacturing costs of the hollow needle 1 'are the same as for the hollow needle 1, except that a stepped embossing die 15 is somewhat more expensive to manufacture than an embossing die 15' provided with a continuously flat embossing surface 17 '.

In any case, with the method according to the invention, the hollow needles 1 and 1 'can not only be manufactured much cheaper, but also better in quality than with the previously used methods, in which firstly a central bore, then the slot and finally the outlet opening in each case for producing the guide channel separate operations had to be generated.

Claims (5)

1. A method for the production of a hollow needle of round steel provided at the rear end with a fitting shank (3) which is thicker in diameter, which needle has a guide channel (10', 10/1) open at the rea end of the fitting shank (3) and terminating radially in arcuate form before the needle point (2) for at least approximately cylindrical cross-pins (20), provided with a filament, of fasteners for labels, buttons or the like which are to be secured to textiles or similar carrier materials, the guide channel (10', 10/1) being provided with a longitudinal slot (22, 22') the width of which is smaller than the width of the guide channel (10',10/1 ), characterised in that for the production of the slotted guide channel (10', 10/1) by means of a side-milling cutter (7, 7') having a U-schaped sectional profile (8, 8'), a U-shaped longitudinal groove (10) is milled from the rear fitting shank end approximately to the needle section narrowing toward the point (2), which groove is wider in the fitting shank (3) in the radial region lying outside the needle diameter (4) than in the radial region lying within the needle diameter (4) and has on both sides step-type marginal faces (12', 13'), and in that then the marginal edges (12, 13, 14, 14') of the U-shaped longitudinal groove (10) are stamped inwards by means of a stamping tool (15, 15') leaving free a radial exist slot (23, 23') situated in the vicinity of the point, which slot (23,23') has the width of the longitudinal groove (10).

2. A method according to claim 1, characterised in that the marginal edge sections (12, 13) of the U-shaped longitudinal groove (10) are undercut in V-form in the region of the fitting shank (3).

3. A method according to claim 1 or 2, characterised in that the marginal edge sections (12,13) of the U-shaped longitudinal groove (10) in the fitting shank (3) have both before and after the stamping operation a greater radial distance from the needle axis than the marginal edge sections (14) of the longitudinal groove (10) in the needle region (4).

4. A method according to claims 1 to 3, characterised in that for the formation of the U-shaped longitudinal groove (10) a disc-type stepped milling cutter (7, 7') is used which is provided on both sides with cutting teeth (9, 9') lying on a smaller radius and protruding symmetrically in relation to the U-section.

5. A method according to claims 1 to 4, characterised in that for the inward stamping of the marginal edges (12, 13, 14) of the U-shaped longitudinal groove (10) there is used a stamp die (15) having stamping faces (16,17) offset in step form in the transition region (5) between the needle diameter and the fitting shank diameter.

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