EP2253180B1 - Apparatus for applying adhesives - Google Patents

Description

The present invention relates to a device, in particular manually manageable device for applying adhesives according to the preamble of the main claim. Such a device, commonly known in the trade as a "hot melt gun", is well known in the art and is known in the art DE 39 06 480 A1 described.

How about the FIG. 1 Illustrated in this prior art document, a solid stick-shaped adhesive member is brought into contact with electrically heated liquefaction means by manual actuation, thereby melting the adhesive member at the end in a melt chamber and allowing the molten adhesive to be applied to an application site through a housing outlet. The document from the prior art also discloses how the liquefying agent is realized as a metal element and heated by means inserted in lateral receiving portions of the metal element heating resistors. Such a known device is usually supplied with mains power and thus wired, so that, by suitable design of the heating resistors, a comparatively high heating power can be brought to the metallic liquefaction body.

However, it is disadvantageous in such devices that the masses involved, in particular the metal element realizing the melting chamber, do not require inconsiderable heating times, with the additional circumstance that heat transfer between the heating resistors and the metallic Body must be overcome, additional power and heating time required.

This, in practical use, typically takes up to about 300 seconds and more for the interior of the melting chamber to reach the desired temperature for liquefying the rod-shaped hot melt adhesive. This then often results in practical use in that, to avoid intermittent cooling and thus re-solidification of the hot melt in the melting chamber, such devices are operated in the continuous on state (steady state heating), which adds to the already considerable electrical energy consumption of such devices further increased. In particular, for a wireless, purely portable realization of a hot glue gun this procedure is therefore unsuitable from the prior art.

Against the background of the task to reduce the (electrically) to be heated mass in order to reduce energy consumption, is from the further prior art, such as WO 2008/006619 A1 a device is known in which the known melting chamber is replaced by an electrically heated, the end face on the adhesive pencil striking grid, which causes local electrical melting of the grating in the forehead area. This can already be achieved a considerable saving of the required electrical heating energy and significant shortening of the heating time, however, this procedure from the prior art is mechanically-constructively complex to implement and leads in unfavorable cases to excessive pressurization of the adhesive element against the grid problems.

Accordingly, it is an object of the present invention to simultaneously improve a heating time between an electrical energy activation and a possible application of the liquefied adhesive a generic device for applying adhesives in view of a reduced electrical energy consumption, thus potentially network-independent operability and such a device the simple, potentially automated and mass-production-ready skill to make, even under tough conditions a trouble-free plastic liquefaction operation should be possible.

The object is achieved by the preferably manually handled and / or designed as a wireless portable unit device for applying adhesives having the features of the main claim; advantageous developments of the invention are described in the subclaims. Independent protection in the context of the present invention is claimed for a liquefaction body according to independent claim 16, which is preferably claimed for use with the device according to one of claims 1 to 15, but also independently of this as an invention.

In an advantageous manner according to the invention, the liquefaction body realized from the electrical resistance material itself, and thus itself (and without external, additional heat generators), becomes a part of the melting chamber in which the end of an adhesive pin is melted by means of the melt contact surface formed by it. In other words, directly and without the interposition of a heat-conducting element (which, depending on the form of implementation, a further development electrical contacting surface for the resistance material of the liquefaction body may be in the area of the melt contact surface and insofar as an electrode forming the melt contact surface is part of the liquefaction body) the heat input to or into the adhesive material takes place, with the obvious consequence of very fast heating time and thus short time to operational readiness, in (by avoiding any unnecessary heat transfer components) optimized electrical energy yield, so that this approach according to the invention is particularly suitable for battery operation.

According to the invention, therefore, the liquefaction body is geometrically designed so that, as a wall of the melting chamber, a sloping surface meets the end of the adhesive pin, which, by its tapered design, tapered design allows the flow of the liquefied adhesive through a passage opening to the housing outlet , In this case, an internal geometry of the liquefaction body or the melt contact surface has been found to be preferred, which tapers (at least in sections) in the manner of a funnel, cone, hollow cone or nozzle, wherein the melt contact surface sections also have a flat surface portion or even designed tapering in a pyramid can be.

According to a preferred embodiment of the invention (Best Mode), the resistance material used for the realization of the liquefaction body is a PTC (positive temperature coefficient) characteristic barium oxide ceramic or a comparable resistance material, wherein, for optimized electrical energy input in such as a hollow cone or funnel-shaped element, the inner and outer surfaces of the body has a (large) surface coating for the realization of electrodes.

In the advantageous embodiment of the invention, such a contact is made by coating with a metal material or other suitable electrical conductor material, in particular manufacturing processes of sputtering, sputtering, (gas phase) deposition or painting have been found to be favorable and preferred, in the context of Invention as "coating" also about a (corresponding to the contour of the melt contact surface or the offered by the liquefaction body inner melting chamber wall adapted) sleeve or the like electrically conductive element comes into consideration. In terms of process technology and for the simple realization of the liquefaction body as an electrically contactable dipole, it is encompassed by further developments of the invention to divide (divide) a coating (eg full area) into two electrodes (electrode portions) suitably with an electrical voltage source are contactable for heating the liquefaction body.

According to a preferred embodiment of the invention, the liquefaction body is provided with a pair of preferably conical-sleeve-shaped electrodes on both sides, ie on its inner side presenting the melt contact surface, so that the electrical contacting via the outer surface (first electrode) or over the inner surface (second electrode, this then also forms the melt contact surface off) is realized. In order to achieve the advantageous thermal advantages in the sense of the invention, such, suitably approximately sleeve-shaped each adapted to the contours of the liquefaction body electrodes are thin-walled relative to a wall thickness of the (eg ceramic) liquefaction body, typically the electrodes have a wall thickness <15% of the wall thickness of Liquefaction body, preferably <10%, and more preferably <5% of the wall thickness of the liquefaction body, so that with a typical wall thickness of, for example, 1.5 mm of the PTC liquefaction body, a typical electrode thickness is about 0.1 to 0.2 mm.

It is also provided in accordance with preferred developments of the invention, the surface applied to the liquefaction body electrodes inextricably applied to this, in addition to a soldering process (particularly suitable the so-called reflow or reflow) also about a connection by means of electrically conductive and suitable thermally resistant adhesive offers.

According to a preferred embodiment of the invention, it is intended to design these as a wireless, portable unit and to provide corresponding network-independent with a recorded in the housing battery unit. Suitably, this is configured modularly removable in an otherwise known manner and z. B. in the form of lithium-ion batteries to make powerful rechargeable.

The inclusion and attachment of the liquefaction body in the housing is preferably isolated (heat), which may be provided for thermal insulation in the mechanical realization suitable air chambers or air cushion. Also it appears, especially from the point of view of mass production, favorable to encapsulate the liquefaction body with a suitable (including electrically insulating) material and expose only corresponding electrical connection areas for contacting or to offer a direct wiring.

With regard to possible (portable) housing forms and implementations, reference is made to the WO 2008/006619 , which in terms of a design and a basic structure of essential functional components, such as with regard to FIGS. 1 to 4 as well as possible transport mechanisms of the FIGS. 5 and 6 , as are considered possible developments of the invention in the present disclosure, as well as a possible pistol-shaped embodiment according to the already in the DE 39 06 480 revealed basic form (which could be replaced by an otherwise known battery module about there provided, handle-side supply of the mains voltage).

More preferably, according to the invention, it is provided, in particular for manual handling (and the associated manual application of force to an applicator tip of the device by manual pressure or the like handling effects of an operator) to store at least the liquefaction body and a (firm) ansitzende application tip so resiliently in the housing in that, in response to pressurization of the applicator tip during the dispensing and application process of adhesive, the unit resiliently yields along the feed axis, insofar as such adverse damage can be prevented or mitigated by unduly large manual application of force.

In addition, according to further developments, it is provided within the scope of preferred embodiments to guide the preferably elongated-rod-shaped adhesive element through a retraction device (retraction means) which, in accordance with further development, exerts a pulling force directed counter to the feed direction onto the adhesive element. A device designed in this way has the additional advantage that, after completing an application process (and terminating a corresponding, manual or automatic feed force on the adhesive element which presses it towards the melt contact surface), the adhesive element is pulled counter to the feed direction by the predetermined retraction stroke Thus, to effectively prevent dripping or after-leakage, assisted by a negative pressure development in the frontal region of the adhesive member in response to the retraction movement, the operability and operational safety are further increased.

As a result, the present invention of directly heating a liquefier body member (suitably providing an inclined melt contact surface) by itself and using it to form a fusion region (melting chamber) of the tackifier rod achieves the intended purpose of minimizing heating times with optimized, to combine for a battery operation suitable energy consumption. Thus, the present invention allows in the manner shown, the simple realization of a highly user-friendly adhesive applicator device, which will make accessible to the traditional only network-bound devices accessible material "hot melt adhesive" in other areas of application.

Figur 1

einen Längsschnitt durch den Verflüssigungskörper, insbesondere zur Verwendung in einer Vorrichtung zum Auftragen von Klebstoffen gemäß einer ersten Ausführungsform der Erfindung;

Figur 2, Figur 3

eine Schnitt- bzw. Seitenansicht einer möglichen Ausgestaltung der Erfindung gemäß einer zweiten Ausführungsform;

Figur 4

ein elektrisches Widerstands-/Temperaturdiagramm zum Verdeutlichen des PTC-Verhaltens des zur Realisierung des Verflüssigungskörpers bevorzugt verwendeten Widerstandsmaterials;

Figur 5, Figur 6

eine doppelte Längsansicht sowie eine Längsschnittansicht einer Vorrichtung zum Auftragen von Klebstoffen gemäß einer dritten Ausführungsform der Erfindung;

Figur 7, Figur 8

eine doppelte Längsansicht sowie eine Längsschnittansicht einer Vorrichtung zum Auftragen von Klebstoffen gemäß einer vierten Ausführungsform der Erfindung und

Figur 9, Figur 10

eine doppelte Längsansicht sowie eine Längsschnittansicht einer Vorrichtung zum Auftragen von Klebstoffen gemäß einer fünften Ausführungsform der Erfindung.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in

FIG. 1

a longitudinal section through the liquefaction body, in particular for use in a device for applying adhesives according to a first embodiment of the invention;

FIG. 2, FIG. 3

a sectional or side view of a possible embodiment of the invention according to a second embodiment;

FIG. 4

an electrical resistance / temperature diagram for clarifying the PTC behavior of the resistive material preferably used for the realization of the liquefaction body;

FIG. 5, FIG. 6

a double longitudinal view and a longitudinal sectional view of a device for applying adhesives according to a third embodiment of the invention;

FIG. 7, FIG. 8

a double longitudinal view and a longitudinal sectional view of a device for applying adhesives according to a fourth embodiment of the invention and

FIG. 9, FIG. 10

a double longitudinal view and a longitudinal sectional view of a device for applying adhesives according to a fifth embodiment of the invention.

The FIG. 1 shows, as with a typical wall thickness of 1 to 2 mm and a typical opening diameter of about 12 mm, tapered to an outlet width of about 3 to 4 mm, formed of a barium oxide ceramic PTC condensing body 10 is tapered tapered , By sputtering, this body 10 is provided with a circumferential metallization, wherein, for potential separation, two circumferential separating cuts 12, 14 separate the metallization into a first, primary outer-shell-side electrode 16 and an inner electrode 18.

The inner wall portion (melt contact surface) 19 is, as in the sectional view of Fig. 1 shown, relative to the supply direction descriptive center axis 21 inclined by an angle 19 of approximately 20 °.

In an otherwise known manner, these electrodes are supplied with an operating voltage (by mechanical and electrical peripherals not shown in detail) and thereupon heat up the PTC resistance material of the body 10 (a typical temperature-resistance profile illustrates FIG FIG. 4 ; the PTC characteristic leads to an increase of the resistance with increasing temperature, which in turn, in the manner of a temperature control behavior, sinks the current flowing through the PTC resistor body).

In the area of the inner metallization 18, the liquefaction body shown in FIG. 1 forms a cone-shaped melt contact surface tapering toward a tapered passage opening 20 for the front end of a (typically cylindrical) glue stick 22, as indicated by the dashed line in FIG FIG. 1 indicated. The virtually immediate heat transfer from the heat generator (resistor element 10) to the solid adhesive 22 leads to very short heating and thus melting times and optimum energy utilization. In practical operation (in battery mode), gluing can be carried out after approx. 10 to 15 seconds.

The FIGS. 2, 3 (where the FIG. 2 a longitudinal section along the section line II / II in FIG. 3 shows) illustrate a slightly varied embodiment: in turn, analogous to the representation of FIG. 1 In the outer jacket region, condenser body 30 formed in a conically tapering manner is provided with a first electrode coating 32 in the inner cone region (simultaneously melt contact surface) with an electrode surface 34, which furthermore continues on the outlet side through a tapered passage opening 36 of the body 30 to an applicator tip 38. At the opposite (ie expanded) introduction region of the liquefaction body 30, the inner coating 34, z. Example, in the area 40, contactable, wherein a cylindrical-sleeve-shaped portion 42 (made of non-electric and non-heat-conducting material) simplifies the guiding of a left side to be introduced Klebsstoffstifts.

With reference to the FIGS. 5 to 10 will be described in the following three other embodiments for the realization of the invention, which are structurally similar to each other, differ only in the central region of the adhesive element guide and are described summarily together. In that regard, the same reference numerals and / or the non-mention of a respective feature of an embodiment are to be understood as an identical realization in the respective other embodiments of the FIGS. 5 to 8 ,

So first shows the FIG. 5 in the schematic longitudinal view in the lower half of the housing of the device for applying adhesives according to the third embodiment in an external view, the upper half of the device with the housing (or removed housing shell). The FIG. 6 shows the sectional view along the section line VI-VI in FIG. 5 ,

More specifically, this embodiment shows (i.ü. also the other embodiments of the FIGS. 7 to 10 ) a two-part housing shell 50, which extends in each case in one piece over the entire length of the device. Two housing halves are aligned with each other, aligned by pin guides or bores 52, 54, and in the exemplary embodiment shown, the pair of housing shells are connected by elastic rings 56 (in the housing inlet area) and 58 (in the front application area).

In this tapered to a housing outlet outlet of the housing sits a conical section Liquefaction body 10 (made of barium oxide ceramic as PTC, as described above), which is provided in the region of its outer shell with a first cone electrode 60 undetachable, in its inner shell region with a second hollow cone-shaped electrode 62, which in the in FIG. 6 shown way through the housing outlet into a cylindrical applicator tip region 64 extends and ends an outlet nozzle 66 (diameter eg 1mm) offers. The inner sleeve 62 and the outer sleeve 60 are non-detachably connected to the ceramic body 10 by a reflow soldering process (which is more preferably carried out in a common processing step for both electrodes) and are in a manner not shown in detail in the figures with a portable power source via a the housing outside sitting (not shown) electrically contacted switch. The figure additionally clarifies a circumferential cavity 63 as a heat-insulating region between the outer electrode 60 and the housing 50.

The FIG. 6 illustrates right of the PTC element realized as a silicone tube hollow cylindrical guide portion 68 through which the round rod-shaped adhesive member (not shown) is guided; this is dimensioned such that a simple sliding of the adhesive element can take place on the inner wall of the hose element 68, wherein a lip-shaped annular shoulder 70 provided in the right-hand region sealingly encloses the adhesive element (and insofar acts as a barrier against possibly exiting molten adhesive material).

The guide member 68 is surrounded by a sleeve member 72 (preferably realized, as well as the pair of housing shells 50, made of a heat-resistant plastic material, such as Ryton) engages via a ring shoulder 74 in the element 68 and is supported via a second shoulder 76 and against the force of a compression spring 78 against an inner annular shoulder 80 of the housing. In this way, the arrangement of silicone sleeve 68, solid plastic sleeve 72 and supported compression spring 78 causes a pressure suspension of the contacted liquefaction body (including the firmly attached thereto outlet 64): a force application of the outlet end 64 would then be transferred to the silicone body 68 and (via a Ring neck) on the solid plastic sleeve 72, which in turn can be supported by means of the paragraph 76 and the compression spring 78 resiliently on the housing shoulder 80. To that extent, a potentially harmful, high force input, such as may result from improper manual handling, can be mitigated - within limits - in its damaging consequences for the overall arrangement.

The embodiment of FIG. 6 (see also FIG. 8 FIG. 10) also discloses a disadvantageous drip-reducing retraction device for the (rod-shaped) adhesive element: As shown in the right-hand region of the housing 50, adjacent the glue pin inlet 82, is a circumferential silicone rubber molding 84 held in the housing so that it is pressed against the force of a second compression spring 86 (which is supported by an inner housing annular shoulder 88) in the direction of the inlet end 82 of the housing, for this purpose, the helical compression spring engages in a suitably sized Ring groove of the rubber molding 84 a.

The molded body 84 has a central, tapered passage area 90, which is adapted to an outer diameter of an adhesive stick to be introduced, that by the action of the rubber material of the body 84, a detent effect arises, while a kraftbeaufschlagtes passing through in the adhesive operation (ie a pressing of the glue stick in the FIG. 6 in the left direction in the direction of the outlet 66) is not hindered. Rather, the rubber-shaped element 84 has the task, in no longer successful Kraftbeaufschlagung the adhesive pin in the direction of adhesive or feed retraction (ie, a movement of the adhesive pin in the direction of the right FIG. 6 effect: by the peripheral adhesive action on the tapered portion 90 namely takes the molding 84, which was moved in adhesive operation and movement of the adhesive pin in the left direction against the clamping force of the compression spring 86 in the direction of the shoulder 88, the adhesive pin back with, so Advantageously, the adhesive pin is pulled out of the engagement region, in particular the direct contact with the (the melt contact surface forming) inner electrode 62. In this way, there is advantageously no further melting by any residual heat after electrical deactivation, in addition, a slight negative pressure, which at the same time retracts any liquid adhesives from the cylindrical end region 64, so that they can no longer escape undesirably from the opening 66.

The third and fourth embodiment differs from the embodiment of FIGS. 5, 6 merely by a slightly different embodiment of the central region of the adhesive guide: Again, in the fourth embodiment, reference is made to the FIG. 7, FIG. 8 , one tubular, hollow cylindrical silicone element 68 a provided which similar to the embodiment of FIGS. 5, 6 is designed. However, this is not surrounded by a cylindrical solid plastic element 72, but carries only behind a ring shoulder 92 a ring 94 of solid plastic material, which in turn, analogous to the functionality of FIG. 6 , serves as an abutment for the compression spring 78 for supporting against the annular housing inner shoulder 80. In this way, in comparison to the realization of the FIG. 6 , Make the middle part less expensive, in particular eliminates the additionally suitable plastic material to be sprayed part 72nd

Another alternative form of realization shows the FIG. 10 , Here again takes a hollow cylindrical silicone body 68b the task of both the leadership, as well as the suspension true, because a radially widening outer wall portion (radial projection) 96 of the element 68b serves both to support against the inner wall paragraph 80 of the housing, as well as a spring element (due the inherent elasticity of the silicone rubber material used for the realization). By this realization, the design effort can be further simplified, being provided, for example by a (not shown) disc or the like. Distance element between the housing portion 80 and the right-hand wall portion of the projection 96, the spring or elastic behavior is adjustable or influenced ,

Not shown in the illustrations are (almost any) variants how the present invention can be implemented in suitable packages; it is, depending on the purpose, low, the condensing body modular To disguise (for example by means of thermally and electrically insulating material) and / or in a (not shown) housing a suitable shell-side heat insulation (also by suitable air cushions or bridges) provided in order to further optimize the thermal properties and thus the electrical energy consumption.

Claims (15)

1. A device for applying adhesives comprising a housing which is configured to receive a fixed pin- or rod-shaped plastic element (22) cooperating with electric heat-generating liquefying means (10) and which at its end offers a housing outlet for outputting an adhesive which is liquefied by the liquefying means,
   characterised in that the liquefying means are realised as a liquefying body (10) made itself from a heat-generating electric resistive material and without external additional heat generators, the liquefying body offering a melting contact surface (18) for cooperating with a frontal end section of the adhesive element, wherein the melting contact surface, relative to an axis (21) extending along a feed-in axis of the adhesive element, is inclined towards this axis by an angle (19) of > 0 ° and < 90°, preferably > 5° and < 40°, further preferably > 10° and < 30°.
2. The device according to claim 1, characterised in that the liquefying body (10) tapers in feed-in direction to become an outlet opening (20) facing in direction of the housing outlet, for the liquefied adhesive in the liquefying body.
3. The device according to claim 1 or 2, characterised in that the melting contact surface is configured as a tapering inner surface (18) and constitutes a surface or section of the liquefying body, which is configured, at least in sections, as a nozzle, a funnel, a hollow cone and/or a pyramid and/or is provided with at least one planar contact surface section.
4. The device according to one of claims 1 to 3, characterised in that the liquefying body comprises a flat electric contacting (16, 18).
5. The device according to claim 4, characterised in that the flat electric contacting (18), at least in sections, is provided in the area of the melting contact surface in such a way that liquefying takes places on the contacting or adjacent to the contacting.
6. The device according to claim 4 or 5, characterised in that the flat electric contacting (16, 18) is applied by applying a metallic material to the preferably ceramic resistive material of the liquefying body by means of coating, in particular vaporising, depositing, varnishing and/or sputtering, or is realised by at least one cone- sleeve-shaped electric conductor element areally connected with the liquefying body.
7. The device according to claim 6, characterised in that the flat electric contacting for creating an electric dual pole comprises nozzle-, funnel-, hollow-cone- or pyramid-shaped conductor elements as a contact electrode pair provided on both sides of the liquefying body.
8. The device according to claim 7, characterised in that at least one of the conductor elements provided on either side of the liquefying body is non-detachably connected with the liquefying body in particular by means of soldering or gluing.
9. The device according to one of claims 1 to 8, characterised in that the liquefying body (10) has an electrical resistance characteristic effecting temperature regulation.
10. The device according to one of claims 1 to 9, characterised in that the liquefying means are supplied off-grid with electric power from a battery unit inside the housing, which in particular may be configured module-like so as to be removable and/or rechargeable.
11. The device according to one of claims 1 to 10, characterised in that the liquefying body is provided in the housing in a heat-insulating manner, in particular by forming an at least partially surrounding air cushion.
12. The device according to one of claims 1 to 11, characterised in that the liquefying body comprising an application tip on the outlet-side is spring-mounted in the housing along the feed-in axis.
13. The device according to one of claims 1 to 12, characterised in that guidance means for the adhesive element are configured such that the liquefying body and the adhesive element, while outputting the liquefied adhesive, are in contact with each other via the melting contact surface through manual, lever or spring action.
14. The device according to claim 13, characterised by retraction means, which for exercising a pulling force directed against the feed-in direction upon the adhesive element, are configured in such a way that the adhesive element, which is load-free in feed-in direction, is moved by a predefined longitudinal stroke against the feed-in direction.
15. The device according to one of claims 1 to 14, characterised in that the housing comprises a switch-on button manually operable from outside for electrically activating and/or deactivating the liquefying means by switching an operating current for the liquefying body on or off.

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