DE2806968A1 - METHOD AND DEVICE FOR REACTIVATING THE MELT ADHESIVE LAYER OF A COATED DOWEL - Google Patents

Description

Reg. No. 3.31 16. 2nd 1978

Karl M. Reich, Maschinenfabrik GmbH, 7440 Nürtingen

Method and device for reactivating the hotmelt adhesive layer of a coated dowel.

The present invention relates to the method and the device for reactivating the hotmelt adhesive layer a coated dowel and for driving it into the bore of a workpiece.

As is known, dowels are used to connect wooden workpieces and are initially about halfway into the prepared Drilled in the first workpiece and glued in at the same time. From DE-OS 24 34 751 is this a portable impact device is known in which the dowels stored in a magazine are fed to a guide channel will. There, the hot-melt adhesive layer of the first dowel is reactivated, i.e. heated, by a stream of hot air and thus brought into an adhesive state. The dowel is then inserted into the prepared using the hammer Drilled hole in the workpiece, where the hotmelt adhesive layer quickly solidifies, so that the dowel is firmly attached to it connects to the workpiece.

This known method now requires devices for heating the air and a number of control elements that ensure the correct chronological sequence of reactivation of the hotmelt adhesive layer and hammering in the dowel. These Facilities make the device more expensive and can lead to malfunctions in robust operation. There is also extra air necessary for the hot air.

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The object of the present invention is therefore to provide a To create a method and a device with which the dowels are driven in in a simple and inexpensive manner can be. The impact device should be robust, with as few additional parts as possible and a long service life exhibit. The susceptibility to failure should be as low as possible.

This object is achieved in that the dowel is driven through a nozzle bore prior to hammering Inside diameter is smaller than the outside diameter of the coated dowel.

In impact tests with coated dowels it has surprisingly been found that in such a case the hotmelt adhesive layer is reactivated. The hot melt adhesive is attached by the strong friction the wall of the nozzle hole can be glued so that the dowel is glued into the dowel hole after it has been hammered into it.

In an advantageous embodiment of the invention, the nozzle bore has a funnel-shaped inlet zone which the The dowel is compacted with the adhering hot-melt adhesive without peeling off the hot-melt adhesive. When moving the dowel The hotmelt adhesive is then heated through the cylindrical nozzle bore until it is adhesive.

In the tests, it has also been found to be advantageous to make the inside diameter of the nozzle bore smaller than the outside diameter of the uncoated dowel. So if this has an outside diameter of 8 mm, then its hotmelt adhesive layer has an outside diameter of 8.6 mm. The inside diameter of the nozzle bore is then expediently chosen to be 7.8 mm, but it can be in the range from 7.6 mm to 7.8 mm. When the coated dowel is driven through .., the nozzle bore will be

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both the hot-melt adhesive layer and the dowel pressed together. The hotmelt adhesive layer, however, has the Exit from the nozzle bore again has an outside diameter of 8.4 mm.

If the dowel has a different outside diameter, the inside diameter of the nozzle bore is the same as the dowel diameter to adapt the corresponding ratio to this.

The present invention enables the hotmelt adhesive layer of a dowel in a surprisingly simple manner to reactivate the impact. There are no expensive and vulnerable additional parts to the actual impact device necessary, the impact device is robust, cheap to operate and has a long service life.

Further advantageous features of the invention are described in the subclaims.

In the following, exemplary embodiments of the invention are described in more detail with reference to the drawings.

Show it:

Fig. 1 side view of part of the impact device according to the invention, partially in the plane of symmetry cut.

FIG. 2 section along line II - II in FIG. 1.

3 shows an enlarged section through a nozzle according to the invention.

Fig. 4 enlarged section through a further embodiment of a nozzle according to the invention.

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The impact device shown in FIG. 1 is is a known, compressed air driven impact device, in which in a housing 1 with cylinder 2 of the Percussion piston 3 with driving ram 4 is mounted so as to be movable up and down. The stroke of percussion piston 3 is over a trigger 5 triggered.

A guide plate 6 is firmly connected to the housing 1 by screws 7. This guide plate 6 has a guide channel 8 which is aligned with the driving ram 4.

A magazine 9 is also attached to the housing 1, in which the dowels 11 connected to form a strip 10 are ready. They are pressed by a spring-loaded magazine slide 12 in the direction of the guide channel 8 Dowels are coated in a known manner over part of their length with a layer of hot melt adhesive 13, which connects the dowels together at the same time. A first dowel 11 is located in the guide channel 8 and lies on its back wall. The outside diameter of the dowel is given by d, the outside diameter of the hotmelt adhesive layer by d2.

A mouthpiece, in which a nozzle 16 is arranged, is fastened to the guide plate 6 with screws 14. This nozzle 16, shown enlarged in FIG. 3, has a cylindrical nozzle bore 17 with an inner diameter d ₃ and a funnel-shaped inlet zone 18. The inlet zone 18 consists of a first, frustoconical section 19 which faces the guide channel 8 and has a relatively large cone angle. It is used to center the dowel to be driven in.

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Between the first section 19 and the nozzle bore 17 runs a second, likewise frustoconical Section 20, which has a relatively small cone angle and in which the compression and reactivation the hot melt adhesive layer takes place. A cone angle of 6 ° has proven to be special for the second section proven to be advantageous, but it can be in the range between 4 and 10, depending on the hotmelt adhesive.

While the inlet zone 18 of the nozzle 16 according to FIG is particularly easy to manufacture, FIG. 4 shows a further embodiment of a nozzle 21, the generatrix of which the inlet zone 23 has a continuous curvature, which, starting from a relatively large cone angle at the inlet, gradually becomes tangential to the cylindrical one Nozzle bore 17 merges.

Immediately above the inlet zone 18, the mouthpiece is provided with an opening 24 through which the hot melt adhesive remains leak themselves or can be easily removed.

To hammer in a dowel 11, the hammering device is in a known manner with its mouthpiece 15 on a workpiece placed so that the nozzle bore 17 is aligned with the bore 26 of the workpiece. After actuating the trigger 5 Compressed air reaches the cylinder 2 from a compressed air source (not shown) via percussion piston 3 and drives this together with the driving ram 4 in the direction of the workpiece, so that the first one lying ready in the guide channel 8 Dowel 11 torn off the strip 10 and in the direction of the nozzle bore. 17 is driven. There will be both the hot melt adhesive layer 13 and the dowel 11 are compressed in the manner described, so that the hot melt adhesive reactivates and heats up will. The dowel is thus after hammering into the

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Bore 26 and firmly glued to the workpiece 25 after the hot melt adhesive has solidified. After letting go of Trigger lever 5 returns the hammer 3 to its upper rest position and the magazine slide 12 is conveyed the strip 10 and thus the next dowel 11 in the guide channel 8.

The invention can also be used advantageously with electromagnetically driven impact devices or with Use stationary dowel driving devices.

Any thermoplastic can be used with "hot melt adhesive" Plastic denotes that can be mixed with fillers and that when heated into an adhesive state transforms.

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Claims (9)

Reg. No. 3.31 16.2.1978 Claims A method for reactivating the hotmelt adhesive layer of a coated dowel and hammering it into the bore of a workpiece, characterized in that the dowel (11) is driven through a nozzle bore (17), the inner diameter d _{3 of which is} smaller than the outer diameter d "des coated dowel. 2) Device for performing the method according to claim 1 with a guide channel for receiving the dowel to be hammered in and a hammer-in ram sliding in the guide channel, characterized that at the outlet end of the guide channel (8) a mouthpiece (15) with the one with the driving ram (4) aligned nozzle bore (17) is arranged. 3) Device according to claim 2, d a d u r c h / g e k e η η records that the inner diameter d_ of the nozzle bore <17) in the range between 95% and 97.5% of the Outside diameter d, of the uncoated dowel (11) is. 4) Device according to claim 2 or 3, characterized in that the nozzle bore (17) at its end facing the guide channel (8) in alignment with a funnel-shaped inlet zone (18) connected is. 5) Device according to claim 4, characterized in that that the inlet zone (18) consists of two frustoconical sections (19,20), wherein the cone angle of the section (19) facing the guide channel (8) is substantially greater than the cone angle of the other section (2öO. -2- 903834/0305 ORIGINAL INSPECTED • et · 6) Device according to claim 5, characterized in that the cone angle of the section (20) facing away from the guide channel (8) is between 4 ° and 10 ° and is preferably 6 °. 7) Device according to claim 4, characterized in that the generator (22) the inlet zone (23) has a continuous curvature. 8) Device according to one of claims 2 to 7, characterized in that the mouthpiece (15) is interchangeably connected to the housing (1). 9) Device according to one of claims 2 to 8, characterized in that the mouthpiece (15) is provided with an opening (24) above the inlet zone (18). -3-