FR2579114A1 - Improved installation for dispensing hot-melt adhesive - Google Patents

Abstract

The invention relates to an improved installation for dispensing hot-melt adhesive, comprising the combination of the following means: a means 1 for supplying and loading with adhesive in the solid state; a melting vessel (kettle) 2 preferably having two chambers 3-4, one 3 premelting the solid adhesive coming from the supply and loading means and the other 4 constituting a reserve of liquid adhesive in direct connection with the means 6 for applying the adhesive of all known types; a means 5-5a for direct connection with the so-called premelting chamber and its level of filling in order, as a function of the latter, to act, likewise directly, on the said supply and loading means, in order to act as a regulator.

Description

The present invention relates to an improvement to hot-melt adhesive distribution installations. The most generally used hot-melt adhesive distribution installations commonly include a melter in which the fusion is carried out. by heat. glue usually in the form of dragees, at room temperature. and glue dispensing devices from this melter
For 1 application of melted glue. two main means are used. namely either by pressurization by pumps and nozzles, the pump sucking the glue through an orifice provided at the bottom of the melter or by contact with the melter then comprising two separate tanks but communicating between cu, the first of these tanks known as a profusion tank melting dragees without disadvantage for the distributor itself, which, read, its found in the melting tank 9a glue then flows from one tray to another according to the principle of va ss commu n7.cants.

 Whatever the formula adopted for these installations, a solid glue supply station must be provided and this supply is generally ensured manually by successive more or less controlled contributions, these contributions being made in small quantities.

These operations are therefore frequent
They are consequently the cause of two kinds of incidents, namely either the defect of product by my that of glue in the event of malnutrition. either the overdose responsible then for overflows of the melter
Various remedies have been sought to alleviate this or these drawbacks. Thus, for example, it has been sought to supply the melters with glue in the form of a liquid.

 Unlike the melter recalled above (of small capacity), in the case of the adoption of the liquid glue supply. a large capacity melter (several liters) is used, in which the change from solid state to liquid state is carried out. The adhesive is then transported using heating pipes but the supplies of solid adhesive are always carried out and checked manually. This system is however expensive to purchase and to use, without however remedying all the drawbacks that it may present.

The present invention proposes to overcome these drawbacks by providing an installation characterized by the combination of the following means
- a means of supply and loading of glue in 1 solid state
- a melter preferably having two enclosures, one providing reflow of the solid glue coming from the supply and loading means and the other constituting a reserve of liquid glue in direct connection with the means for applying the glue of all known types
- a means in direct connection with the so-called prefusion chamber and its filling, for example. depending on the latter. also act directly on said supply and loading means, to play the role of regulator.

 According to other characteristics. said regulating means advantageously comprises a probe sensitive to variations in the level of molten adhesive.

 According to a particular embodiment, said probe is of the capacitive type which does not come into contact with the bed of molten glue.

 Other characteristics and advantages of the invention will emerge more clearly from the description which follows, given with regard to the appended diagram illustrating a possible installation in accordance with the invention.

 Referring to this diagram, there is shown at 1 a loading hopper which can be of any known type. This loading means is designed so as to be able to deliver solid glue (for example in the form of sugared almonds) in a supply line shown schematically in la, by any suitable means for advancing the solid material and under controlled control. a regulating means which will be described below. This supply line opens into a capacity 2 divided by a partition 2a to define two chambers 3 and 4 communicating with each other, the lower part of the partition 2a being disposed at a certain distance from the bottom of the capacity 2. The chamber 3. which constitutes the so-called prefusion chamber is loaded with solid glue (dragees) 3a. A heating means (not shown) allows this solid glue to melt. The resulting liquid occupies the volume available in the two communicating chambers 3 and 4. A system known as applicator of known type is directly charged with the liquid glue from chamber 4. In the free volume situated above the glue in fusion brought in solid form into the prefusion chamber 3 is provided a probe 5 preferably of the adjustable capacitive type (C = a few picofarads) and with high sensitivity. This probe is in connection with an electronic control system of any type 5a which, as indicated above acts directly on the supply means of the pipe la. this command and control link being designated by the arrow F.

 The level of adhesive in the prefusion tank 3 can be maintained thanks to the regulating system 5-5a of the electronic type and the probe of which is adjustable in position. while not being in direct contact with the molten medium. As a result, the probe is protected from dirt, thus avoiding measurement errors.

 The electronic assembly in question is adjusted for a given level and when this level drops below a fixed threshold, the probe sends information to the regulator 5a activating the supply system 1 for a time t. which is thus controllable, making it possible to measure the supply of solid glue.

Such regulation therefore calls for a variation in the frequency of the contributions. in order to make them equal to consumption in the distribution system 6
By having an installation of the type which has just been described, it is immediately apparent that the contributions of solid adhesive are provided in a controlled manner. These contributions can be very high (several tens of kilograms). thus ensuring the running of the distribution system on line at high speed, for several hours, even several days.

 Of course, all the metal parts of the installation according to the invention and in particular of the supply system will advantageously be treated with non-stick coatings, in order to avoid sticking of the dragees, in particular at the level of the melter. The discharge chute of the loading means 1 will be closed by a valve (not shown) which will limit the heating of the dragees awaiting distribution.

Thus, the installation according to the invention has many advantages
- fully automatic operation
- simple construction
- low energy consumption
- security.

 It goes without saying that the present invention has only been described for purely explanatory and in no way limitative of the present invention and that any modification in terms of equivalences may be made by those skilled in the art, without departing from its frame.

Claims (2)

CLAIMS loading, to play the role of regulator. directly for said supply means and - a means (5-5a) for direct reading with the so-called prefusion chamber and its filling level so, depending on the latter, also act - a melter (2) preferably having two speakers (3-4). one (3) carrying out the prefusion of the solid glue coming from the supply and loading means and the other (4) constituting a reserve of liquid glue in direct contact with the means of application (6) of the glue of all known types:: - a means for supplying (1) and loading glue in the solid state Improved installation for the distribution of hot-melt glue. characterized in that it comprises the combination of the following means  1. Advanced installation according to  claim 1, characterized in that said mean  (5-5e) regulated advantageously includes a probe (5)  are @@@ aux @@ ctions of molten glue level.  2. Advanced installation according to  claim 1 or 2, characterized in that said probe (5. 5e) - capacitive type does not come into contact with the bed of molten glue.