DE2165071A1 - Gun for dispensing a melted hot glue - Google Patents

Description

PAITNTANWKLTE

DIPL.-ING. GÜNTHER KOCH DR. TINO HAIBACH

8 MUNICH 2, December 28, 1971

OUR MARK: 13 557

COOPER INDUSTRIES, IUC. HOUSM, TEXAS 77002 / USA

Gun for dispensing a melted hot glue

The invention relates generally to devices for dispensing adhesives that melt at high temperatures, also referred to below for short as hot melt adhesives bezeifanet, us this concerns in particular pistol-like, hand-held devices with a heated melting chamber through which a high Temperature meltable thermoplastic adhesive forced through is to be melted and applied to a surface of a workpiece via a nozzle. Such Devices are now commonly referred to as "hot glue guns".

It has been shown that hot glue in the form of thermoplastic materials and the like for the most diverse Applications are very suitable, and therefore their use has become widespread. There are already several constructions of hand-held pistol-like designs Devices for dispensing hot melt adhesives have been developed in which the adhesive is in the form of a solid solid rod, fed to a heating channel in which it is melted and then extruded through a narrow opening and on the surface to be provided with the adhesive

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to be brought. Various arrangements are used here to apply a force to the rod-shaped adhesive to apply so that the melted glue over a Nozzle is dispensed and applied to the desired area; For example, the glue gun is designed so that the User can apply pressure to the exposed rear end of the glue bar with their thumbs to move them toward to move towards the dispensing nozzle; alternatively, rotatable transport wheels, ratchets or similar devices are used. However, this makes it difficult to reduce the manufacturing costs of such glue guns and at the same time to provide properly working mechanical feed devices, which serve to apply a force to the KIefc to move berstange in the direction of the dispensing nozzle, and it is difficult to prevent unwanted leakage or dripping to prevent liquid glue from coming out of the nozzle when the device is not in use. With a known glue gun A device with a ratchet and a puller is used to advance the adhesive days, and this gun has a nozzle that must be turned with the help of a wrench to close a valve provided in the nozzle, or to open so that no melted adhesive can escape or drip off when the gun is not in use.

The invention is based on the object of a new type of hand tool for dispensing a hot glue bwz. a hot glue gun for a thermoplastic pillow glue, in which a device that is under Peders tension is provided, which serves to continuously move the solid hot glue rod towards the front dispensing end to bias a heating chamber, and in which it is made possible in an expedient manner, for the purpose of refilling further insert existing rods into the gun with a hot glue. Also according to the invention is a novel hot melt glue gun created, which comprises a heating chamber, also a dispensing nozzle, against which a consisting of the hot melt adhesive

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existing rod is biased, as well as a valve device that closes automatically to prevent the escape of To prevent melted adhesive over the dispensing opening, as long as there is no protruding from the dispensing opening of the nozzle Part of the valve device is pressed against a surface to which the adhesive is to be applied. Farther is a novel hand tool of the kind mentioned for dispensing an adhesive created according to the invention, the one Includes device with a pressure piece or piston, which serves to bring the solid glue supply in Eichtung on the heating chamber and to advance the discharge nozzle, this device Can be easily removed when cleaning the tool or replacing the device with a new device shall be.

The invention and advantageous details of the invention are explained in more detail below with reference to schematic drawings of exemplary embodiments. It shows

1 shows, in perspective, a hand tool for dispensing a hot glue or a hot glue gun;

FIG. 2 shows the hot glue gun according to FIG. 1 in a section along the line 2-2 in FIG. 1;

3 schematically shows the electrical circuit of the heating device the hot glue gun;

4 and 5 each show a cross section along the line 4-4 and 5-5 in Fig. 2;

6 shows, in an exploded perspective partial representation, the removable nozzle, the tapering one Part of the melting chamber and the 'parts of the valve device the hot glue gun;

209848/0 0-9

Fi. 7 shows a horizontal section along line 7-7 in Fig..2;

8 shows, in a partial section, the melting chamber and the dispensing nozzle of a modified embodiment of a hot glue gun;

Figure 9 is a section along line 9-9 in Figure 8;

10 shows a further modified embodiment of a melting chamber and a dispensing nozzle in longitudinal section; and

11 shows a section along the line 11-11 in FIG.

In the drawings, there are corresponding parts each denoted by the same reference numbers} the illustrated, hot glue gun, designated as a whole with 12, comprises a gun-like housing which is made up of two to one another Matching housing halves 13A and 13B assembled and an upper main portion 14 and a pistol grip 15 comprises. In the upper area of the housing halves 13A and 13B is a elongated tubular melting chamber 16 which includes a cylindrical tubular portion 16A, which extends over the greater part of its length, and at the front end a truncated cone tapering towards the front has shaped portion 16B, which protrudes from the gun housing 13 and in an external thread provided annular end portion 16G ends which encloses an outlet opening 17 of small diameter. Of the rear part of the uniform diameter, generally cylindrical barrel section IbA of the Schiuelzkaüiiner an upwardly directed loading opening 18 is formed, which communicates with a loading space 19 stands, which is delimited by the housing halves 13A and 13B, opens at the top of the housing 13 and it allows hand in the uniform diameter barrel portion 16a of the melting chamber

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insert a supply of glue in the form of a cylindrical rod.

A dispensing nozzle 21 is screwed onto the free end portion 160 of the melting chamber 16 and has a through bore 22 which at the foremost end of the nozzle comprises an outlet portion 22A of smaller diameter, a central portion 22B with an average diameter and an internally threaded rearward Larger diameter portion 220 that is screwable onto the annular end portion 160 of the melting chamber. Furthermore, a valve body in the form of a pin 23 is provided which comprises a thinner, elongated cylindrical section 23A which is mounted in the bore section 22 of the nozzle and protrudes from the free end of the nozzle, and a section 23B of larger diameter with a frustoconical end face facing the annular transition surface between bore sections 22A and 22B that forms a valve seat, and a stem section 230 that protrudes rearwardly through the conical section 16B of the chimney and through a triangular support disc 24 generally coaxial with the exit port 17 is held. The shaft section 230 between the actual valve body 23B and the support disc 24- is provided by flattening or in some other way with outwardly projecting lugs 23C ¹ , which come to rest on the support disc when the pin 23 is pushed inwards by its front Approach 23A is pressed against the surface of a workpiece in order to limit the axial inward movement of the valve pin 23 and thereby set its opening stel development.

Through the open rear end of the melting chamber 16 protrudes forward a push rod 25, which at its front End of a cylindrical piston 26 made of polytetrafluoroethylene

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whose outer diameter corresponds to the inner diameter of the portion 16A having a constant cross section corresponds to the melting chamber; the piston 26 is held in position on a rod part 27 by disks 26A, and about the pole 2? To support concentric with the barrel portion 16A, a guide plate is on the housing 13 28 attached, which has a guide opening through which the rod 27 protrudes. The free rear end of the rod 27 carries a button 2A outside the housing 13 and behind the housing.

According to FIG. 2, a spring 30 is provided which serves to push the melted adhesive out of the nozzle 21. The leather 30 is arranged in a cylindrical tube 31 through which the spring is guided and which is arranged below the axis of the push rod 27 and parallel to it. The front end of the spring 30 is attached to a pin or anchoring section of the housing 13 in the manner indicated at 30A in FIG. 2, while the rear end of the spring is connected to a forwardly projecting cylindrical extension 32A of a manually operated device 32 which has an opening 32B for receiving a finger of the user and is used to apply a pulling force to oil spring 30. The Ansazt 32A is arranged in the rear end of the spring guide tube 31, and the guide tube is z. B. connected by an inwardly projecting indentation 31A. The front end of the guide tube 31 is provided with an extension 31B so that the circular outer hand of this extension cooperates slidingly with a cylindrical cavity 33 which is formed by two opposing sections of the housing halves 13A and 13B. The front end of the device 32 is inclined upwards and forwards so that it is inclined to the rear end of the upper main portion 14 of the housing 13

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fits, and this device is provided with a forward opening recess 32C which the button 2? A of the Push rod 2? can take up releasably.

That part of the barrel section 16A of the melting chamber, which is between the loading opening 18 and the conical Section 16B of the melting chamber extends, is surrounded by an electrical heating element 34, which is of a tubular sleeve 35 made of metal is enclosed, the at the same time defining an elongated, generally cylindrical tree 35A- for receiving a thermostat; this space extends along the underside of the socket 35 and includes a removable cylindrical probe section a thermostat switch 36 on · The heating element 34 comprises a casing made of a mica flat material, the Z. B. helically on the barrel portion of the Melting chamber 16 is wound; furthermore is a first Winding layer made of resistance wire, e.g., chrome-nickel wire, provided, which lies between successive layers of the mica material and a heating coil HW-I forms with a power consumption of 150 watts; furthermore the heating element comprises a second outer winding HW-2, which forms a ballast winding, on their mode of operation in the following in the description of the associated electrical Circuit is received. Between certain layers of the mica material, strips of nickel or similar thin conductive strips can be arranged, which form the supply lines for the heating windings described.

When the hot glue gun is to be loaded, the spring-loaded device 32 is pulled back against the force of the spring 3 ^ until the recess 320 has released the button 27A of the push rod; then the device 32 is rotated about the longitudinal axis of the Federführun ₌ srohrs 31 so that the training with the

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section provided with recess 32C opposite the axis of the attachment. Set 32A extends in side viewing. Then will the push rod 27 is pulled back as far as it will go to move the piston 26 to a position just behind the loading opening Bring 18; this rear position of the piston is determined by a stop screw 37; then becomes a The rod 20 consisting of the hot glue is inserted by hand into the melting chamber 16 via the openings 19 and 18. Now the push rod 27 is advanced by hand to move the rod 20 in sight of the nozzle, and the Device 32 becomes one behind button 27A Point withdrawn and rotated back up so that the recess 32C is aligned with the button 27Aj now the spring 30 is allowed to move the device 32 forward pull so that recess 320 receives button 27A and a spring force is applied to the push rod 27, through which the push rod is advanced to the inserted rod 20 up to the stop in sighting on the conical Section 16B of the melting chamber 16 to advance. WM the heating element 3 ^ switched on in a manner still to be described, in order to heat and melt the hot glue in the melting chamber 16, the action caused by the spring 30 the push rod 27 exerted force that the hot melt glue forward into the conical section 16B of the melting chamber and is pressed into the bore portion 22B of the nozzle 22, where the hydraulic pressure generated in the melting chamber to the Effect comes, so that a force acts on the valve pin 23, which the valve body 23B against the seat at the transition between the nozzle bore portions 22A and 22B. Becomes the outwardly protruding portion 23A of the valve pin pressed against a surface to be applied hot glue, the valve body 23B is pushed backward from its Seat lifted so that hot glue can escape from nozzle 21.

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The hot glue gun is designed so that you can get about a whole stick and a half of the hot glue required to fill the portion of the melting chamber 16 of an empty gun 25U that extends from the front end of the feed opening 18 extends from forward. The length of the stroke length of the push rod 27 between the position at which is the piston 26 at the front end of the loading opening 18 is located, and the front end of the stroke is chosen so that when using the tool only an amount of hot glue that corresponds to a fed rod 20 can be consumed. if When the push rod reaches the front end of its stroke length, the gun can therefore be operated with another hot glue rod and then immediately used again, as there is still melted hot glue in the foremost Part of the melting chamber is located.

The pressure that the melted hot glue will put on the inner end of the valve body 23B of the valve pin 23 causes the valve to be held normally closed. When the push rod is with the piston has moved to its foremost position, it could no longer exert any pressure on the hot glue when the valve is open and valve pin 25 could be any take up the position in which the valve is open or almost closed or fully closed. To get out of this To avoid resulting difficulties, measures are taken to inevitably close the valve for to ensure the event that the piston 26 reaches its foremost position · For this purpose, the cylindrical Shank portion 23C of the valve pin protruding rearward from the valve body 2JB is dimensioned so that the piston 26 comes into contact with the adjacent end of the shaft portion 230 and the spring force just before the Moment can act on the valve stem in which the

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Piston reaches the front end of its lifting rod »Tuck Force then holds the valve pin in its closed position, in which the valve body 2 *> B rests against its seat, until the pistol is loaded again.

The thermostat switch or the temperature-dependent switching device 36, the probe section 36A of which protrudes into the sauna 35A delimited by the socket 35, is preferably designed so that the probe section comprises a socket made of ceramic material in which, coaxially with it, a socket that expands when heated rod is arranged made of metal which is fixedly connected to the front end portions of the probe with the socket w · or abuts it. This rod protrudes from the other end of the socket made of ceramic material and cooperates with a «spring-like actuating arm or the like of a switch, once the rod has expanded a predetermined amount to open two switch contacts which are normally closed. until they are lifted from one another by the expanding rod.

The gun's electrical circuit is in working order. 3 shown schematically. In the preferred embodiment, a first heating element and a main heater HW-I is provided, which is connected to a power source through a protective device W OTP against overheating and (thermostatic switch 36 are connected, the latter a second heating element or a Ballastheizelement EW The thermostat switch remains closed until the hot glue gun has heated up to the temperature set with the aid of the thermostat, which in practice is, for example, about 175 ° C.

When connecting the gun to a power source * heating element Hw-I is because with the current source through the ^s lchlosse-

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NEN thermostat switch 36 connected so that the melting chamber 16 is heated quickly. In an expedient embodiment the first heating element works with a power consumption of about 130 watts to heat up quickly to allow the melting chamber. The thermostat is thermally coupled to the heating element HW-I in that it is in the Space 35A is located in close proximity to the turns of the heating element; it opens as soon as the melting chamber has a Temperature of about 175 ° 0 reached. As soon as the thermostat switch 36 opens, the current flows through the first heating winding HW-I, the second heating winding HW-2 and the lamp IL, which therefore lights up. The illumination of the lamp indicates to the user that the tool is ready for use. The second heating coil or the ballast heating element HW-2 is dimensioned so that the tool stabilizes at a temperature which is higher than the switching temperature of the thermostat switch 36, so that this switch is open and the lamp IL remains on. The second heating coil HW-2 can e.g. B. be dimensioned so that a total of about 0.27 A flows through the circuit, whereby the entire Power consumption, including that of the indicator light, is reduced to about 31 watts. The lamp met two tasks, d. that is, it indicates that the melting chamber has been heated to the correct operating temperature and it also illuminates the workplace.

The overtemperature protection OTP is thermally coupled with the heating elements and comes into effect by melts when a predetermined excess temperature is reached, to finally break the circuit so that the pistol can only be used again after it has been repaired has been. If necessary, the overtemperature protection could be connected in series with the thermostat switch 36 may be provided in the line which bridges the second heating coil HW-2 and the lamp IL, so that at one

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If the thermostat switch fails, the overtemperature protection could interrupt the circuit of the thermostat switch. In these circumstances, once plugged into a power source, the tool would be on all the time, it would requires a considerably longer heating-up time, but overheating would not occur.

With the construction of the hot glue gun described above, in which the withdrawal of the rod 27 with the piston 26 from the melting chamber normally by the Stop screw 37 is prevented, and in which the guide part 28 releasably connected to the housing 15 by the screw 28A is, you can easily remove the rod 27 with the piston 26 when the tool is cleaned or the piston and Rod assembly is to be replaced. For this purpose, the user simply pulls the device 32 backwards to withdraw the recess 32C opposite the button 27A of the rod 27, then it rotates the device 32 by about 90 ° to a lateral position and finally it removes the Bolts 28A and 37 »after which the entire piston and rod assembly can be removed.

If necessary, an additional measure can be used to ensure that the valve body 23B always comes to rest on its seat when the valve pin 23 is brought out of contact with the workpiece; to this end, w is possible to provide a biasing spring 4-0, on the valve stem 230 between the valve body 23B and the guide plate is pushed and 24 of FIG. 8 and 9 supported on these two parts. The spring 40 therefore applies an elastic biasing force in the forward direction to the valve body 23B of the valve pin 23 in order to vorzusapnnenj the valve body against the valve seat and the nozzle.Here, the spring 40 acts in the same sense as the hydraulic pressure of the melted adhesive in the front part of the melting chamber 16, which is also on the valve body a

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Closing force always applies when the valve pin is lifted from the workpiece and therefore move outwards can.

Figs. 10 and 11 show another modified embodiment in which in the converging portion 16B of the melting chamber, a valve guide and acceleration part 42 is provided, which is made of aluminum and a cylindrical tubular core portion 43, which on the shaft portion 230 of the valve pin 23 slidably is led; Furthermore, the component 42 comprises four wing sections 44 with a longitudinal profile that is substantially corresponds to a right triangle or a truncated triangle; these wings are angularly spaced from 90 ° around the axis of the core portion 43, and its outer edges are in intimate contact with the inner surface of the conical section of the melting chamber 16. Thus, the component 42 made of aluminum facilitates the transfer of heat from the heating element 34 · and the wall of the Melt chamber out via the wing sections 44 to the adhesive in the converging section 16B of the melt chamber. In the illustrated embodiment, the tubular core portion 43 has at its rear end an inwardly projecting annular shoulder defining an opening which is sized to its diameter corresponds almost to the diameter of the shaft portion 23C of the valve pin, so that the rear end of the valve pin 23 is slidably guided through this opening in a central position. Fig. 10 also shows another construction a stop for limiting the inward movement of the valve pin 23. In the construction according to FIG. 10, the approaches 230 * shown in FIG. 6 are omitted, and there is a short tube 45 made of steel is provided which the Shank section 230 of the valve pin immediately behind the Surrounds valve body 23B; the length of the tube 45 is chosen so that the pipe comes to rest on the support disc 24,

20 98A870096 ORIGINAL tNSPECTEO

as soon as the valve pin reaches its predetermined innermost position, so that any further inward movement of the valve pin is prevented. In a corresponding manner, instead of the tube 45, a tightly wound spring could be used, the total length of which corresponds to the length of the ear 45, and which is pushed onto the shaft section 20 % the total length of this spring is also chosen so that it rests against the Support disk 24 comes as soon as the valve pin 23 reaches its intended innermost position, so that further inward movement of the valve pin is prevented.

Claims :

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Claims (13)

Δ Κ SPHlCHE Gun for applying a melted hot glue to a surface of a workpiece, g e k e η η draw et by a housing (13), a tubular melting chamber (16) with an elongated cylindrical Section 0-6A) for receiving a solid rod (20) made of a thermoplastic adhesive its rear end, a heating element assembly (34) for Heating the melting chamber and melting the stick of adhesive located therein, one on the front end The nozzle (21) which is detachably arranged in the melting chamber and has a through hole (22) which has an outlet opening (1?) for dispensing the melted hot melt adhesive and is provided with a valve seat, one with the valve seat cooperating movable valve body (23B) with an actuating pin (23A) which passes through the outlet opening protrudes and can be brought into contact with a surface of a workpiece to be moved so that it lifts the valve body from the valve seat, a push rod assembly (25) which is slidably guided in the melting chamber and axially reciprocable, and a spring (30) coupled to the push rod assembly her can be released and then, when it is coupled to the spring, serves to make the push rod assembly resilient biasing forward to advance the stick of glue and cause the melted hot glue to exert a pressure on the valve body which tends to abut the valve body in its closed position to bring the valve seat. 2. Gun according to claim 1, characterized in that the push rod assembly (25) between a rear and a front limit position is movable, and that the valve body (23B) has a shaft ab- 209848/0096 section (230) comprises, which from the valve body after protrudes back to a point at which with it the push rod assembly cooperates when this reaches its front limit position to the valve body in its closed position to be brought into contact with the valve seat. 3.. Pistol according to claim 1, characterized in that the melting chamber (16) is one in the forward direction conically tapering front portion (16B) which ends at an outlet opening, which is in communication with the bore (22) of the nozzle, and that the valve body (23B) has a shaft portion (230) extending rearward through the conical portion of the * melting chamber to a point with which the push rod assembly (25) cooperates when #ie reaches a predetermined forward position, to cause the valve body to be pressed against the valve seat and brought into its closed position will. 4 ·. Pistol according to claim 1, characterized in that the spring is a helical spring (30) which can expand and contract along a spring axis parallel to the axis of the melting chamber (16), that a fixed anchor (30A) is provided for the front end of the spring, and that a movable holding " part (32) is provided which is guided so that it can be advanced and withdrawn along the spring axis, and which is mounted so that there is an angular movement about the spring axis from a first position in contact with the Push rod assembly (25) can lead in a second position from *, in which it is opposite the spring axle in extends laterally. 5. Gun according to claim 4, characterized in that the push rod assembly has an in 209848/0096 the melting chamber (16) comprises movable piston (26) and a piston rod (27) which extends from the piston to the rear and out of the rear end of the housing (13), and that the holding part (32) extends one forward
has opening recess (320) from which the rear end of the piston rod can be received. 6. Pistol according to claim 2, characterized in that the spring is a helical spring (30) which can expand and contract along a spring axis parallel to the axis of the melting chamber (16),
that a fixed anchorage (30A) is provided for the front end of the spring, and that a movable holding part (32) is provided which is guided so that it can be advanced and retracted along the spring axis and which is mounted so that it can perform an angular movement about the spring axis from a first position in contact with the push rod assembly into a second position in which it is laterally offset with respect to the push rod assembly. 7. Pistol according to claim 6, characterized in that the push rod assembly has an in the melting chamber comprises movable piston (26) and a piston rod (27) extending rearwardly from the piston and extends out of the rear end of the housing, and in that the retainer has a forwardly opening recess has, from which the rear end of the piston rod can be received. 8. Pistol according to claim 3 »characterized in that the spring is a helical spring which can expand and contract along a spring axis parallel to the axis of the melting chamber, that a fixed anchorage for the front end of the helical spring
is provided, and that a movable holding part is provided 209848/0096 hen is guided so that it is advanced along the spring axis and can be withdrawn, and which is mounted so that there is a winker movement about the spring axis from a first position in contact with the piston rod can run into a second position in which it is opposite the piston rod is offset laterally. 9 · Pistol according to claim 8, characterized in that the push rod assembly has an in the melting chamber comprises movable piston and a piston rod extending rearwardly from the piston and protrudes from the rear end of the housing, and that the holding part has a recess opening to the front, from which the rear end of the piston rod can be received. 10. Pistol according to one of claims 4, 6 and 8, characterized in that the housing (13) has a Cylindrical guide (33) concentric with the spring axis and open in the direction towards the rear end of the housing comprises, and that the holding part (32) is provided with a cylindrical tube (31) which is opposite the holding part protrudes forward, encloses the helical spring (30) and has a cylindrical contact surface (31B), which by the Inner surface of the guide is guided to hold the holding part relative to the housing in a predetermined position. 11. Pistol according to one of claims 1 to 3 »characterized in that a valve spring (4C) is provided, which cooperates with the valve body (23B) to move it elastically into its closed position To pretension the system on the valve seat. 12. Pistol according to claim 1, characterized in that the Heizelementanorünung (34) heating windings (HW-I, HW-2), which surrounds the Schme chamber 209848/0096 give, also a sleeve (35) made of metal, which the heating coils and includes an outwardly extending extension which has an elongated space (35A) for receiving it a ', thermostat (36A) which is connected to one point of the circumference extends substantially over the length of the heating coils, and a thermostat switch (36). To regulate the power supply to the heating coils, the thermostat or the probe being arranged in the space mentioned is. 13. Pistol according to one of claims 1 to 3 »characterized in that the heating element arrangement (34) comprises a first heating winding (HW-I) with a predetermined power consumption, which causes rapid heating of the hot glue in the melting chamber until the hot glue melts, when connected to a power source, further a thermostat switch (36) which is in a first circuit which includes the first heating coil, so that the first heating coil can be connected to the power source until a predetermined temperature is reached in the melting chamber, and a second circuit with a second heating coil (HW-2), which forms a ballast winding, which is connected in series with a lamp (IL) and in parallel with the first circuit to reduce the strength of the current flowing through the first heating coil when the the! thermostat switch opens, so that the current strength assumes a value at which the through the heating coils generated temperature stabilized at a value which is slightly higher than the actuation temperature of the thermostat switch ₉ while at the same time the lamp is turned on. 209848/0096 Blank page