FI66546C - ADJUSTMENT OF THERMAL PLASTING OF THERMOPLASTIC LIMEEMNE - Google Patents

Description

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Federal Republic of Germany Förbundsrepubliken Tyskland (DE) P 2936531.9 (71) Hilti Aktiengesel1schaft, 9494 Schaan, Liechtenstein (LI) (72) Martin Költer, Fiirstenfeldbruck, Federal Republic of Germany Förbundsrepubl iken Tyskland (DE) ) Apparatus for melting and dispensing thermoplastic adhesive -Anordning för smältning och dosering av thermoplastiskt 1imämne

The invention relates to a device for melting and dispensing a thermoplastic adhesive. The device comprises at least two controllable heating stages and a housing partially formed as a handle.

Thermoplastic adhesives are increasingly used in fastening technology. Their advantages are the fast loading capacity, the absence of volatile solvents that are hazardous to health, and the possibility of detaching the joint by heating. In addition to clean production processes, hot melt adhesives are also used in installation technology. In that case, the problem is the partly long breaks that occur between individual uses. If the device is switched off completely during these breaks, it will take a relatively long time before it is switched on again before the device is at operating temperature again.

These types of devices are sensitive to known nm. From U.S. Patent Nos. 2,444,137 and 2,827,181 and U.S. Patent Nos. 3,744,921, 4,059,204 and 3,665,150.

In one known device, the time required for heating is reduced so that the heating procedure takes place in two steps. In the first step, the more intense heating step is brought to a certain temperature. Once this is achieved, the thermal switch switches on the weaker heating phase, which is only set for the adhesive dosing temperature.

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However, if the melt is not dispensed for a long time, there is a risk of overheating in this appliance. To avoid this, the device must be switched off during longer breaks. In this case, however, the user must decide whether it is a longer or shorter downtime. This is often very difficult to deduce and imposes an additional burden on the user. If the appliance is switched off too often, unnecessary waiting times will occur, if it is switched off too infrequently or not at all, there is a risk of overheating.

The object of the invention is therefore to avoid overheating and excessive cooling of the thermoplastic adhesive melting and dosing device during work breaks.

According to the invention, this is achieved in that the handle has control devices which, when relaxed from the handle, cause a change from a stronger heating step to a weaker heating step.

With the device according to the invention, the user does not have to decide on switching off during work breaks. Another essential advantage is that the device does not cool completely, but its temperature drops below the temperature of the adhesive and the machine components to an undamaged temperature. Thus, when put back into operation, the time required to reach the operating temperature is very short.

In principle, arbitrary switching elements, such as switches, pushbuttons or foams, can be used for the connection. However, since most of them have protruding parts and are susceptible to mechanical wear, it is advantageous if a touch-sensitive sensor switch is provided on the handle. The connection occurs when the user's hand only touches two parts. Such sensor switches are now also used in consumer electronics and are therefore very inexpensive elements.

When working with a hot melt adhesive device, very short downtimes often occur, in which case, for example, a part has to be installed in a certain position. Then the device is placed on the slab for a short time. In order to avoid a drop in temperature now, it is expedient if the switching from hotter to cooler takes place with a time delay.

Thus, unnecessary waiting times can be avoided with a view to overheating.

In the following, the invention will be explained in more detail by means of an exemplary drawing showing the device according to the invention from the side.

The device according to the invention consists essentially of a housing 1 in which a handle 2 is arranged laterally. The handle 2 has an electric cable 3 and a button 4. When the button 4 is used, a glue body 5 formed as a cylindrical rod is transferred to a melting chamber. It then presses a part of the melt in the melting chamber and forces it to come out of the dosing nozzle 6 at the front end of the housing 1. Aeration slots 7 are arranged on the opposite side of the handle 2 to cool the device. There is a sensor switch 8 on the side of the handle 2. The sensor switch 8 acts to switch on the lower heating phase when the handle 2 is removed. If the user grabs the device again and at the same time touches the sensor switch 8, the higher heating phase is automatically switched on again.