EP0024086B1

EP0024086B1 - Apparatus for producing a retaining device for nails to form a row of nails

Info

Publication number: EP0024086B1
Application number: EP80900466A
Authority: EP
Inventors: Erik Berendtsen; Peder Pedersen
Original assignee: Nordiske Kabel OG Traadfabriker AS
Current assignee: Nordiske Kabel OG Traadfabriker AS
Priority date: 1979-02-22
Filing date: 1980-09-10
Publication date: 1983-03-23
Also published as: DK147012B; JPS56500209A; WO1980001790A1; NO803092L; NL8020073A; GB2053839A; CH642586A5; SE8007394L; GB2053839B; NO154958B; BE881882A; NO154958C; DK147012C; EP0024086A1; DK76679A; CA1146059A; SE423887B

Abstract

In the production of rows of nails in running lengths or measured lengths for use in nail guns, the nails (3) are placed in a row of parallel grooves (2) in the periphery of a wheel (1). A groove (7) extending along the periphery of the wheel is approximately as deep or a little deeper than the grooves (2) and intersects the grooves (2) at the centre thereof. Bands (8) are applied on both sides of the groove (7) in spaced relationship with the groove, and a third band (9) is applied on top of the bands (8) to form a cavity defined by the bands (8 and 9) and by the wheel periphery with the groove (7). Liquid resin is introduced into said cavity and solidifies to form a panel (10) which abuts the row of nails and has projections extending between and gripping at least partly around the nails.

Description

The invention relates to an apparatus for producing a retaining device for nails to form a row of nails for use in a nail gun, the nail heads preferably having an at least approximately conical underside; the object of the invention is to produce such a retaining device in the form of at least one panel of polymeric, preferably thermoplastic material abutting one side of the row of nails and having at least one row of projections which are narrow compared to the width of the panel and extend between the nails to secure them, using a method known "per se", comprising disposing into grooves in the peripheral surface of a wheel rotating about a horizontal axis and applying the polymeric material during the rotation of the wheel, in order to obtain such an arrangement of retaining device that the nails may be ejected from the retaining device without any risks of material being carried off from the retaining device itself, since any material torn off from said device would be pulled down into the nail hole and would cause great trouble there.
It is known to produce rows of nails by coating the nails disposed in grooves in a wheel with a plastic material, e.g. as described in the U.S. Patents 3 303 632 and 3 432 985. However, these known methods do not provide for the formation of a panel on one side of the row of nails and thereby the desired safe guiding of the nail row through a nail gun; another point is that the row of nails produced in this manner involve a great risk of the plastic material being torn off when the nail is ejected.
For instance U.S. Patent 3 303 632 teaches the use of a rotary wheel with a peripheral row of nail-receiving grooves and a wide peripheral groove intersecting the nail-receiving grooves and having a depth a little greater than the nail-receiving grooves; this peripheral groove receives hot liquid polymeric material and forms it into a panel embedding the nails with a uniform large width, identical with the width of the peripheral groove, all over its depth and specially where the nails are embedded in it.
The object of the present invention is to provide an apparatus permitting a very rapid and simple manufacture of a retaining device with a panel having projections which secure the nails so that they will be released from the panel as easily as possible. This is achieved according to the invention in that for the purpose of forming said narrow projections with a weakened line or similar indication for release of the nails, said wheel is provided with at least one narrow groove or slot in the peripheral surface of the wheel, said slot extending longitudinally of the row of nails and having approximately the same depth as or somewhat greater depth than the nail-receiving grooves.
With such an apparatus, the nails will thus form part of the mould in which the polymeric material is cast, and the nails may be placed in the mould quite easily and in a manner known in connection with other retaining devices. When the hot, liquid, polymeric material flows down into said slot it will, depending upon the depth of the slot, enclose the nails more or less so as to secure them as effectively as desired, while still ensuring release of the nails from the projections by operation of the nail gun without any risks of undesired plastic portions being torn off.
When the depth of the slot is the same as or a little greater than the nail-receiving grooves, a small opening of weakened line will be formed in the projections surrounding the nails, ensuring that the nail will be ejected from the retaining device itself when it is urged axially forwards by means of the impact mechanism fitted in a nail gun. The nail head, which should preferably have a conical underside, then serves to urge the panel aside and to break the weakened line, but the nail head may also be shaped differently, it being only necessary to adapt the edge of the panel facing the nail head so as to obtain a corresponding wedge effect.
The hot, liquid, polymeric material is supplied continuously during the rotation of the wheel. The nails are then placed in a manner known per se in the grooves in the wheel periphery, said grooves extending either in parallel with the wheel axis or obliquely, the latter often being desirable in order for the nails to be placed as closely adjacent one another as possible. The wheel is then rotated at a suitable speed of rotation so that the plastic material continuously solidifies when forming the panel and penetrating between the nails and down into said slot.
Spreading of the plastic material for forming the panel may, in a way, be controlled by selection of outflow velocity, temperature and rate of feeding. However, the invention relates to an apparatus permitting a quite precise shape of the panel to be achieved so that it can, as is often desired, be used as a guide in the nail gun as well. Such an apparatus comprises a wheel rotating about a horizontal axis and having grooves in its outer periphery for receiving each nail, and is characterized by at least one slot in the peripheral surface of the wheel extending longitudinally of the row of nail-receiving grooves having approximately the same depth as or a little greater depth than the nail-receiving grooves, and that movable forming means, e.g. forming bands or forming wheels, are provided for controlling the spreading of the hot, liquid, polymeric material forming the retaining device and for forming the panel, said forming means being caused to follow the periphery of the wheel over a distance sufficiently long for the applied hot, liquid, plastic material to solidify within said distance into a shape determined by the profile of the forming means. The forming means may be constructed in many different ways, depending upon dimensions and the polymeric material used, it being important that the solidified material does not adhere to the forming means, and that the temperature at which the materials concerned are sufficiently fluid, is so low as to avoid damage to the forming means, which, if they are bands, must be of a flexible material. Since such a continuous row of nails is often to be coiled up, it is usually necessary to employ a thermoplastic material. It has been found that certain types of polyethylene have a very low softening point and bring about so little friction in relation to the forming means and solidify so quickly that the entire method will be carried out extremely easily and quickly when using such a material. At the same time the friction in relation to the nails is comparatively insignificant without being so low as to endanger the required securing, but the nail is ejected from the retaining device without much loss of power.
A functionally particularly advantageous embodiment of such an apparatus is characterized in that said forming means comprise two movable bands abutting and following the surface of the wheel so as to define the two edges of the panel, and an additional band for forming the back of the panel, said additional band abutting the outer face of said first-mentioned two bands.
The invention will be described in greater detail below with reference to the drawing, in which

Fig. 1 shows a part of an apparatus for carrying out the method of the invention, and
Fig. 2 shows a section taken along the line II-II in Fig. 1.

The drawing shows a part of a wheel 1 whose outer periphery is provided with grooves 2 for receiving nails 3 supplied from a feeding channel 4. The wheel 1 rotates in the direction shown by the arrow 5, and the retaining device for the nails is provided at the upwardly facing part of the wheel where plastic material, preferably a thermoplastic polymer, is supplied through a nozzle 6.
As appears from Fig. 2 the wheel is provided with a peripherally extending slot 7, and the nails are additionally kept in place by means of two running bands 8, which also serve to define the region in which the plastic material is to solidify to form the panel 10 of the retaining device. Simultaneously with this, the plastic material will penetrate down between the nails and into the slot 7 that has such a depth as to form small projections which grip each nail and have a clearly weakened line at the side of the nail facing away from the panel 10. To assist a quite precise casting of the panel, a running band 9 is provided that abuts on the top of the two bands 8, and which thereby defines completely the mold cavity in which the panel is to be formed.

Claims

1. An apparatus for producing a nail retaining device which comprises at least one panel of polymeric material, said panel abutting the side of the row of nails and having at least one row of projections which extend so far between the nails as to secure the nails against the panel, simultaneously facilitating the release of the nails, said apparatus comprising a rotary wheel, the outer periphery of the wheel being provided with grooves for receiving a row of nails and with an annular channel extending in the direction of the row of nails and extending to a depth corresponding approximately to the bottom of the grooves for the nails and said apparatus also comprising means for supplying liquid polymeric material to the row of nails, characterized in that the: apparatus is further provided with movable forming means (8, 9) for controlling the spreading of the liquid polymeric material, said means (8, 9) being caused to abut the wheel (1) over a distance sufficiently long for the supplied liquid polymeric'material to solidify and form the panel (10) into a shape determined by the profile of the forming means (8, 9) and in that the annular channel (7) of the rotary wheel (1) defining the row of projections is narrow compared with the width of the panel (10).

2. An apparatus in accordance with claim 1, characterized in that the narrow channel (7) has a depth slightly greater than the depth of the grooves (2) so as to form a weakening point in the projections enclosing the nails (3).

3. An apparatus according to claim 1, characterized in that said forming means (8, 9) comprise two movable bands (8) abutting and following the surface of the wheel (1) so as to define the two edges of the panel (10), and an additional band (9) for forming the back of the panel (10), said additional band (9) abutting the outer face of said first-mentioned two bands (8).