JPH1170355A - Apparatus for applying molten adhesive - Google Patents

Abstract

(57) [Summary] An apparatus for applying a molten adhesive, comprising:
In a type in which a solid molten adhesive is melted in a heatable melting tank 1 and discharged to an application point via a pump mechanism, the apparatus is remarkably compacted, and Prevents leakage of molten adhesive. SOLUTION: A piston pump 20 comprises a pump casing having a suction opening and a discharge opening, and a piston 10 guided in a pump passage, and a spring is provided directly between the suction opening and the discharge opening in the pump passage. The only valve that is loaded is arranged, and the pump piston is screwed vertically into a pump fitting that is embedded in the bottom 17 of the melting tank and is inseparably connected to the pipeline of the pipeline system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact apparatus for applying a molten adhesive, in which a still solid molten adhesive is melted in a heatable tank and supplied to an application point by a pump mechanism. Then, the present invention relates to a type in which the state is changed from a liquid aggregation state to a solid aggregation state.

[0002]

2. Description of the Related Art The above-mentioned exchange of the aggregated state is performed by cooling in a conventional molten adhesive. The cured molten adhesive is liquefied by reheating to a predetermined temperature. Of increasing importance is a PU-fused adhesive that reacts with the moisture in the air and eventually cures, ie, does not allow re-melting of the cured adhesive with ambient air. The advantages of PU-melt adhesives are high strength and high temperature and moisture resistance. Due to the permanent curing properties of PU-fused adhesives due to reaction with air, processing of PU-fused adhesives requires special technical measures to avoid unintentional or premature curing . Therefore, the parts of the melting tank and of the applicator which come into contact with the molten adhesive must be sealed off from the surrounding air, which is achieved, in particular, by the use of protective gas. Leakage of the PU-molten adhesive from moving components with sealing elements, such as drive elements or pistons, can lead to hardening of the adhesive and thus to failure of the device.

[0003] Conventional mechanisms for the supply of melted adhesive are gear pumps and single-acting or single-acting piston pumps. Known gear pumps have a relatively complicated construction and require high construction and maintenance costs, especially in the case of processing of air-hardened PU-melt adhesives. Such a device for the treatment of molten adhesives is described in particular in European Patent Application EP-0150337A1.

[0004] European Patent Application EP-0074839A
No. 1 and European Patent Application EP-0075428A
In the apparatus for applying a molten adhesive known from Japanese Patent Publication No. 1 (1993), a single piston pump of the backward operation type is used for supplying the molten adhesive. Driving is performed by a vibrating air motor (Luftmotor). Such piston pumps also have a relatively complicated structure, and their production costs are extremely high. Furthermore, the construction length is long, and the use of two ball valves is necessary. Particularly in the treatment of highly viscous adhesives, the flow of the adhesive and, consequently, the continuous supply of the adhesive to the application site may be interrupted due to the narrow flow passage.

[0005] EP 0 462 386 A1 describes a double-acting piston pump which is intended to enable an improved flow of highly viscous materials. However, such measures also require high costs in connection with manufacturing and maintenance, based on the four movable components, the valve arrangement and the location to be sealed against the medium to be supplied.

[0006] The devices described so far have further common drawbacks. To allow quick and accurate gluing at any time after the interruption, a certain supply pressure must always be maintained, i.e. the pump mechanism will always be Must be driven. This requires special measures, especially with regard to work safety.

[0007] Utility model G901366 of the Federal Republic of Germany
From US Pat. No. 0.8, there is known a device for applying a molten adhesive, in which a piston is movably arranged in a horizontally arranged guide channel below the melting tank. A piston, which can be driven via a rapidly rotating electric motor, discharges the molten adhesive through a ball valve to an outlet opening. Since the piston is reciprocated very rapidly in the guide passage, a sufficient quantity of material is discharged from the melting tank to the supply hose, so that the drive does not have to be constantly running to maintain working pressure. However, since only one suction opening is arranged in the guide passage,
The suction capacity is significantly lower overall. As a disadvantage, the production costs for providing long guideways are high. In this case, as a further disadvantage, high demands are placed on the sealing of the piston outlet opening, which are not completely achieved and leaked molten adhesive accumulates on the piston. If an air-hardened PU-melt adhesive is used, the melt-adhesive causes the piston to adhere and tighten, thus causing equipment failure. Attempting to avoid the flow of molten adhesive under supply pressure with a high sealing force results in an undesired reduction of the effective motor output or a stoppage of the motor. Furthermore, the arrangement of the ball valve at the end of the penetrating guide passage is inconvenient, since in the case of cleaning such a valve, the hose connection must be disassembled. When the drive motor is shut off, it is difficult to start the piston in the position where it is moved deepest into the suction passage, especially in the case of high-viscosity adhesive, because the piston is not pressurized at the pressure generated in the position. Is the most difficult to exercise.

[0008] In all known means, the construction and arrangement of the fittings and the line system and the heating device are inadequate. Attempts are made to ensure sufficient and uniform heating of the melting tank with the smallest possible structure for the electrical heating device, with the necessary connections and pipes for the supply pump and the discharge of the discharged adhesive. The road system is also trying to heat optimally. European Patent Application EP-0748
In the means described in JP-A-39A1, an individual collection pipeline block is arranged below the bottom of the tank. In this case, too, the arrangement for the tight connection of the connecting line between the tank bottom and the collecting line block is disadvantageous, and the heat transfer between these two components is disadvantageous.

[0009]

SUMMARY OF THE INVENTION An efficient and compact apparatus for applying a molten adhesive is provided, in which the molten adhesive flows out in the form of a leak stream despite the low demands on the sealing procedure. Rather, the structure and maintenance are to be significantly simpler.

[0010]

According to the present invention, a piston pump comprises a pump casing having a suction opening and a discharge opening, and a piston guided into a pump passage. The only valve that is spring-loaded directly between the suction opening and the discharge opening in the pump channel, the pump piston is embedded in the bottom of the melting tank and cannot be separated into the pipeline of the pipeline system Screwed vertically into the pump fitting connected to the Advantageous configurations of the invention are set out in the dependent claims.

[0011]

Advantages of the device according to the invention are, in particular, that the adhesive does not leak out of the guides of the movable component. Due to the simple sealing of the tank, the device is particularly well suited for the treatment of air-hardened PU-melt adhesives. The maintenance-free hinged connection between the piston rod and the piston by means of a flexible element allows the hinge (joint) to be located as deep as possible inside the melting tank, and therefore the piston and the piston pump have a horizontal orientation. Only a small force is generated.

Simple and maintenance of the tank chamber with respect to the surrounding air by sealing between the piston rod and the upper tank wall using a seal plate pressed from the outside to the wall of the melting tank with a spring so as to be movable in the horizontal direction. Free airtight closure is possible. Since little friction occurs between the piston and the seal plate and between the seal plate and the wall of the melting tank, a large amount of motor power is used for sucking and discharging the molten adhesive.

Another advantage of arranging the spring on the piston rod is that the crank drive does not stay in the lower dead center position when the drive motor is shut off, thereby avoiding difficult starting during reconnection.

By arranging a plurality of suction openings in the pump housing, a significantly better suction efficiency is additionally obtained. Due to the vertical arrangement of the pump mechanism, which operates solely with one ball valve, a short construction which is technically favorable is possible. Pump casing with ball valve,
By forming it as a pre-manufactured unit that can be screwed into a pump mounting buried in the tank bottom, simple assembly and maintenance are possible. By arranging the control valve also vertically and easily accessible from above, a simple metering of the adhesive to be dispensed is possible. A pipeline system pre-buried at the bottom of the tank, and
Optimal heating of the melting tank, the feed pump, the relief valve and the line is achieved by means of a heating device arranged in close proximity to the lines and fittings of the line system. Furthermore, a very compact construction is possible with the design according to the invention of the melting tank, and there is no need for pipeline connections which must be made compact to the outside.

The vibrations caused by the imbalance of the drive are guided vertically towards the bottom of the device due to the horizontal arrangement of the electric motor, so that no unwanted movements, such as a horizontal wobble of the device, occur anymore.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The melting tank 1 is provided with a cover opening 18, which can be closed by a cover (not shown) if necessary. A piston rod opening 26 is arranged on the upper wall of the melting tank 1 next to the cover opening 18, and the piston rod 19 projects through the piston rod opening, and the crank drive of the drive motor 2 which is immovably arranged on the frame. It is connected to the section 7. The piston rod 19 is hingedly connected at its lower end to the piston 10 via a flexible element 25 capable of transmitting pushing and pulling forces. In order to seal the inside of the melting tank 1 from the outside air, the seal plate 8 is loosely arranged on the piston rod 19, and the sealing plate is always pressed against the upper wall of the melting tank 1 by the compression spring 27. . The seal between the seal plate 8 and the piston rod 19 is preferably provided by a seal lip (Dic
htlippe).

The pump casing 9 of the piston pump 20
Have a pump passage 15 in which the piston 10 is guided. In the schematic diagram of FIG. 2, the piston pump 20 is shown without the piston 10. Pump passage 1
5 is a pump casing 9 above the bottom of the melting tank 1.
It is connected to the inside of the melting tank 1 via a horizontal suction opening 11 arranged therein. The pump channel 15 is formed in a stepped manner in the lower region and forms a valve seat for the valve ball 12 of the only ball valve 22. The valve ball 12 is under the action of a valve spring 13. The pump passage 15 has a horizontal discharge opening 1 below the ball valve 22.
6. The pump casing 9 is screwed into the pump mounting part 4 with screws 24. The pump mounting part 4 is a non-separable component of a previously formed pipeline system 21, which is embedded in the bottom 17 of the melting tank 1.
(eingiessen).

Another component of the pipeline system 21 is a hose connection mounting portion 6 and a relief valve mounting portion 5, and a relief valve 14 is screwed into the relief valve mounting portion. Individual pipelines 3 and mounting portions 4, 5, of pipeline system 21
Disposed only slightly from the periphery of 6 is an electric heating element 23, which is buried together with the pipeline system 21 in the bottom of the melting tank 1 (FIG. 3). In FIG. 1, the heating element is not visible.

A heatable hose is connected to the hose connection mounting portion 6, and a coating gun is mounted at the other end of the hose. The operating device of the application gun is connected to the control device of the drive motor 2.

For the application of the molten adhesive, the molten adhesive is put into the melting tank 1 in a solid state. Air-hard PU
-Molten adhesive (luftaushaertender PU-Schmelzklebstoff)
In the case of using the cover opening 18, the cover opening 18 is hermetically closed by a cover (not shown), and the remaining internal space of the melting tank 1 is filled with a protective gas. A heating element embedded in the bottom of the melting tank 1 heats the entire melting tank 1 to melt the molten adhesive. Due to the arrangement of the piston pump 20 and the relief valve 14 in the associated mountings 4, 5 embedded in the bottom of the melting tank 1, the piston pump and the relief valve are also heated simply and optimally. After the molten adhesive has completely dissolved, the actuator of the application gun (not shown) is operated. At this point, the electric drive motor 2 is connected and drives the piston 10 via the crank drive 7 and the piston rod 19, preferably at 1400 revolutions / minute (U / min). In this case, the lower end of the piston 10 passes through the suction opening 11 and vibrates. During each upward movement, the ball valve 22 is closed and a corresponding amount of molten adhesive from the melt tank 1 is pumped through the suction opening 11 into the pump passage 1.
It is sucked in 5. When the piston 10 is moved downward again, a part of the melted adhesive which has been sucked is pushed back into the melting tank 1 through the suction opening 11 again, while another part, which is sufficient in quantity, is opened ball Valve 2
2 and the discharge opening 16 are press-fitted into the pipeline system 21. Due to the high speed of the oscillating movement of the piston 10, the molten adhesive is continuously and sufficiently supplied to the application point. Immediately after the operation of the application gun is stopped, the drive motor 2 is shut off.
In order to avoid undesirably high pressures in the line system 21 during operation of the piston pump 20 or to limit or regulate the amount of molten adhesive to be supplied to the hose connection fitting 6, the closing pressure of the relief valve 14 Is adjusted appropriately. That is, when the adjusted closing pressure is exceeded, a part of the supplied molten adhesive flows back into the melting chamber of the melting tank 1 via the relief valve 14.

Since the hinged connection between the piston rod 19 and the piston 10 consists of a maintenance-free flexible element 25, the connection is inside the melting tank 1, ie, It can be provided as far as possible from the crank drive 7. Therefore, the horizontal force acting on the piston pump 20 due to the pivoting movement of the piston rod 19 is reduced to a minimum. The sealing plate 8 is made of a material with good sliding properties, so that it can be moved along the wall of the melting tank 1 following the pivoting movement of the piston rod 19 easily and in a sufficiently sealed state (FIGS. 4 and 4). (Fig. 5). Automatic post-adjustment action of the compression spring 27 (selbstnachstellende Wir
kung) makes the seal maintenance-free.

Further, the compression spring 27 disposed on the piston rod 19 prevents the crank drive unit 7 from stopping at the bottom dead center position when the drive motor is shut off.
At the bottom dead center position of the crank drive, the piston 10 is in a working position that requires a high driving force based on the pressure generated in the pump. If the piston 10 stops at the lowermost position when the drive motor 2 is shut off, it becomes difficult to start when the piston 10 is reconnected. To avoid this, the compression spring 27 causes a return rotation of the crank drive 7 to the top dead center position where the movement is easy.

[Brief description of the drawings]

FIG. 1 is a side view of the device according to the invention, partially broken away without the frame and the cover.

FIG. 2 is an enlarged view of a piston pump.

FIG. 3 is a plan view of a pipeline system.

FIG. 4 is a schematic view of the course of movement of a crank drive unit and a piston pump.

FIG. 5 is a schematic view of the course of movement of a crank drive unit and a piston pump.

[Explanation of symbols] 1 melting tank, 2 drive motor, 3 pipeline,
4 Pump mounting part, 5 Relief valve mounting part, 6 Hose connection mounting part, 7 Crank drive part, 8 Seal plate, 9 Pump casing, 10 Piston, 11 Suction opening, 1
2 valve ball, 13 valve spring, 14 relief valve, 15 pump passage, 16 discharge opening,
17 bottom part, 18 cover opening, 19 piston rod, 20 piston pump, 21 pipe system, 22 ball valve, 23 heating element,
25 deflection element, 26 piston rod opening, 27 compression spring

Claims (5)

[Claims] An apparatus for applying a molten adhesive, comprising: a melting tank that can be heated by an electric heating element; and a piston pump that is driven by a rapidly rotating electric motor to discharge the molten adhesive. A piston pump (20) comprising a pump casing (9) with a suction opening (11) and a discharge opening (16) and a piston (10) guided in a pump passage (15). A single spring-loaded valve is arranged directly between the suction opening (11) and the discharge opening (16) in the pump passage (15), the pump piston (20) being melted The bottom of the tank (1) (17)
Applying a molten adhesive characterized in that it is screwed vertically into a pump mounting part (4) buried therein and inseparably connected to the line (3) of the line system (21). Equipment for. 2. A piston rod (19) and a piston (1).
The connecting hinge between the first and second parts (0) consists of a flexible element (25), which is arranged inside the melting tank (1) and which seals the piston rod (19) for sealing the piston rod opening (26). 2. The method according to claim 1, further comprising the step of disposing a plate, wherein the sealing plate is movably in contact with the wall of the melting tank by the force of the compression spring. apparatus. 3. In the bottom (17) of the melting tank (1),
A relief valve mounting part (5) connected to the pipeline system (21) is buried, and in the relief valve mounting part,
3. Apparatus for applying a molten adhesive according to claim 1, wherein the spring-loaded and adjustable relief valve (14) connected to the melting tank (1) is screwed vertically. 4. The pipe system (21) embedded in the bottom (17) of the melting tank (1) has one or more hose connection fittings (6). An apparatus for applying the molten adhesive according to claim 1. 5. An electric heating element (23) comprising a line (3) and a mounting (4, 5, 6) of a line system (21).
5. The molten adhesive according to claim 1, which is arranged in the vicinity of the periphery and is embedded together with the pipeline system in the bottom (17) of the melting tank (1). Equipment for.