JPS5953105B2 - Equipment for melting thermoplastic materials and making them available for use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for melting a thermoplastic material and making it available for use, and in particular to a device for melting a thermoplastic material and making it available for use. This invention relates to a test device for melting a plastic adhesive material.

Conventionally, in thermoplastic adhesives, also referred to as so-called "hot melt" adhesives, the conversion of the material from the solid phase to the molten state is carried out in a tank with heated walls.

The molten material is maintained in a molten state in a tank in sufficient quantity to accommodate the use of one or more applications. If the amount used is large, the amount of material retained in the molten state will be correspondingly large. Such a large amount increases the warm-up time needed to start up the device and exposes at least a portion of the molten material to heat and/or oxygen for an extended period of time. Most thermoplastic adhesive materials deteriorate due to oxidation when exposed to heat and/or oxygen for extended periods of time. It is therefore desirable to minimize the time that the material remains in the molten state, and this can be achieved by balancing the rate of melting with the rate of consumption. No. 549,18, commonly assigned U.S. Patent Application No. 549,18.
No. 9 (U.S. Patent No. 3964645)
No. 105,361), which is a continuation-in-part application, discloses an apparatus for melting and putting into use large quantities of thermoplastic materials, and this apparatus is a melting apparatus with an extremely high melting capacity. It also has a pump that can handle materials with extremely high viscosity.

However, such high-efficiency equipment has caused the following problems that could not have been anticipated in the past with respect to certain materials.

That is, although the device is operating, the following problem occurs when consumption is not achieved at the planned consumption rate.

That is, in that case, the rate at which the melter melts the material is greater than the rate at which it consumes the material, causing molten material to overflow from its storage chamber and back up into the melter and into the hopper. ). If the equipment is temporarily stopped under these conditions, with molten material remaining inside, this material will solidify and form a bridge across the hopper, which will have to be remelted. This is difficult and takes a long time 5, which prevents the charging of solid material from the hopper to the melting device. Therefore, a primary object of the present invention is to prevent the backflow of molten material into the hopper and the accompanying bridging of solid material between the hopper walls.

Another object of the invention is to limit the amount of molten material retained in the storage chamber by preventing back flow upstream of the hopper.

These objectives may be accomplished by providing a device to maintain the material in the lower part of the hopper at a temperature substantially below its freezing point. As long as the hopper walls are maintained at a temperature below the freezing temperature of the material, no material will flow back up into the hopper and therefore no crosslinking will occur in the hopper walls. According to the present invention, an air chamber is provided by surrounding the bottom of the hopper with a shroud, and air is forced to flow through this air chamber during use of the apparatus, thereby preventing the molten material from flowing backward.

This forced draft flows over the walls of the hopper and acts to cool the hopper and keep it substantially below the melting point of the thermoplastic material. In one embodiment, airflow through the air chamber is induced by a fan mounted to the wall of the shroud.

In other embodiments, the pump used in the device is an air-operated pump whose exhaust air is used to provide air flow through the damper.

In any case, the type of air source does not matter.
The important thing is that the air flow is sufficient and
The thermal conductivity of the hopper walls is high enough to dissipate more heat than is supplied by the molten material flowing back. The above-mentioned and other features of the invention will become apparent from the description given below with reference to the accompanying drawings.

1 and 2, the thermoplastic material melting and dispensing apparatus 5 of the present invention has a housing 10 in which a hopper 11. Grid type melting device 12, storage room 13
, a gear pump 14 and a manifold block 15 are provided.

A solid thermoplastic material 6 in the form of blocks (FIG. 4), pellets (FIG. 6) or blocks is placed on top of the hopper 11, from where it sinks through the open bottom and into the grate melter 12. surface. The grid type melting equipment is
It is heated and the solid material that comes into contact with it melts. The molten thermoplastic material 7 is conducted through a passage 16 at the bottom of the grate melter 12 into a storage chamber 13 directly below it. The bottom walls of the storage chamber] 7, 18, 19 are sloped so that the molten material can reach the inlet 20 of the pump 14.
I'm starting to be guided by this. The material is conveyed by this pump to a manifold block 15 and from there through a hose or conduit 21 to one or more adhesive applicators 22 of conventional type. The housing and hopper housing 10 includes a plate-shaped metal substrate 25 and a cover 26 mounted on the top thereof.

The force bar 26 surrounds two compartments of the applicator, namely a melting compartment 27 and a control compartment 28. Both compartments are separated by an insulating barrier, not shown. The control compartment houses all of the electrical equipment responsible for regulating the temperature of the entire device. The devices in this control partition may be, for example, 1
It may be of a commercially available type, such as that of the type shown in U.S. Pat. isn't it. The top 30 of the cover is provided with an opening 31 into which the hopper 11 and a shroud 29 fit. The hopper has a vertical tube 32, the bottom 33 of which is open;
Moreover, the top part is closed by a lid 34. A flange 35 is welded around the hopper for use in mounting the shroud 29, as will be described in detail below. Grate-type melting device As shown in FIGS. 2, 3, and 4, the grate-type melting device 12 includes:
It has a container for receiving the solid thermoplastic material falling from the hopper.

The container has four side walls 37, 38, 39, 40 and a bottom flange 41. The bottom part has a plurality of vertical protruding heating elements 43, each of which has a polygonal cross-section at the base and a truncated conical top. The protrusions are arranged in longitudinal rows 44, with adjacent protrusions 45 in the same row integrally joined to each other.

Between adjacent rows, the arrangement of the protrusions 45 is offset in the longitudinal direction so that when viewed from the top surface, the protrusions present alternate rows and columns, and the columns are separated by the intervening rows of protrusions. It is arranged in such a way that it can be melted.

On both sides of each row there is an open passage 16 opening towards the top of the storage chamber 13 and extending over the entire length of the row.

In melting thermoplastic materials, it is important that the melting equipment have as much surface area as possible in contact with the material agglomerates or pellets of low thermal conductivity.

Since the application of the present invention, U.S. Patent No. 3,531,02
As shown in No. 3, a measure was taken to increase the surface area by forming ribs on the bottom of the grate melting apparatus.
Grid type melting device 1 using a truncated conical heating element of the present invention
2 is 40% more effective than the conventional type with ribs for the same lattice surface temperature. Therefore, the material and the slanting material 1jj and the spinning material 1 are also broken.
The truncated cone or truncated pyramid shaped projection has a flat top surface 50. In the following specification, the term "cone" is used to include pyramid shapes having from three to an infinite number of sides. However, if the number of sides of this pyramid is infinite, the cross section of this protrusion will be circular. Cutting off the top to form the top end 50 increases the contact area with the solid thermoplastic material;
A uniform surface temperature throughout the cone can be maintained with minimal input. In one preferred embodiment:
The grid-type melting device 12 is formed as a monolithic casting.

The casting has three feet 52 formed on each end wall and a pair of feet 53 on the front and rear walls. Each leg is provided with a vertical hole for accommodating a bolt (not shown), by means of which the lattice-type melting device is attached to the top of the storage chamber 13, and furthermore, a gasket is suspended and held at the top of the melting device. A plate 55 can be attached. Gasket 56 connects the top of the grate melter and
The hopper tube 3 is held between the hanging holding plate 55 and
2 and prevents gas from escaping into the atmosphere from around the hopper.

Gasket 56 also makes it possible to create a vacuum within hopper 11, or alternatively to maintain an inert atmosphere. Such a vacuum or inert gas atmosphere is used to minimize deterioration of the molten material.
Adopted in some specific cases. In the illustrated embodiment, the grate melter has an integral annular boss 54 extending forwardly from its front side wall.

Boss 54 also has three equally spaced legs 57 around its outer wall. This foot 57 is provided with a bolt hole for receiving a bolt (not shown) for attaching the melting device to the top of the storage device. There are nine horizontal holes 60 extending through the base and front wall of each row of heating projection elements 45.

Each horizontal hole 60 has a resistance type electric heater 61.
are loaded, with one heater extending past the base of each row of truncated conical heating elements. Furthermore, there is a hole 63 extending through the rear wall, which is adapted to accommodate a temperature sensing device, not shown. This temperature sensing device operates to maintain the temperature of the heater element 61 at a predetermined temperature. The rear wall of the melter block is provided with a transverse hole 64 in which a thermometer 65 of the conventional type is housed, the front face 66 of which is located on the control panel of the housing 26.

Storeroom Storeroom 13 has an open top and a bottom melter fixed to a grid-type melter.

Between the reservoir of the storage chamber 13 and the bottom of the grid-type melting device,
It is desirable to provide an insulating gasket. The storage chamber has shallow side walls 70, 71 and a shallow rear wall 72.

The front wall 73 is slightly deeper so that the bottom of the storage chamber is tapered from the front and side walls towards the front opening 75 of the front wall 73. Through this opening 75, the molten material is led into a recess 76 formed in the pump mounting boss JMOV of the storage chamber.
This recess 76 intersects with a vertical hole 83 extending from the bottom of the boss J-mo V toward the recess 76. Pump 14 is placed in this hole 83 and bolted to manifold block 15.
The boss J-MoV has a base 78 whose flat bottom surface abuts and is supported by the manifold block 15.

The manifold block, on the other hand, is located on and carried by the base 25 of the housing. The manifold block 15 and the pump mounting bosses J and V are connected to each other by bolts (not shown) passing through vertical and directional bolt holes provided in both. In the preferred embodiment, two U-shaped resistance heaters 85 are installed on the bottom wall 1 of the storage chamber.
7, 18, and 19.

Moreover, a tube 87 is further provided on the bottom wall 18. A temperature sensor is inserted into the tube 87, and is used to control the amount of electricity supplied to the heater 85 in order to maintain the temperature of the bottom wall at a predetermined temperature.

In the lower part of the side wall of the storage chamber a transverse hole 82 is provided, into which a conventional thermometer 89 is inserted, the front part of which is placed in the control panel of the housing 26.

As shown in FIG. 5, heaters 85 are placed on both sides of the pump 14 to uniformly heat the pump 14 and the manifold 15. Pump The top surface 92 of the pump 14 forms a coplanar continuation of the sloped surface of the bottom wall 18 of the storage chamber.

In the preferred implementation, this surface is sloped at an angle of about 5 DEG to the horizontal, and the slope allows the molten material to flow naturally down toward the inlet of the pump 20. The pump 14 is provided with a pair of shafts 94 and 95 that rotate in opposite directions.
It extends above the shaft, and its rotation directs the material between the two shafts towards a rear cover wall 97 formed in the cover 98.

The wall 97 projects over and covers the pump inlet hole 20 and slopes toward the inlet hole 20 so that material previously in contact with the wall 97 flows toward the pump inlet hole 20. ing. In addition to the end plate 96 and its associated suction device, the pump includes a pair of intermeshed gears 10 keyed to the drive shaft 94 and the driven shaft 95.
It has 3,104.

Both gears rotate in a generally quatrefoil shaped recess 105 in stator 106 . One leaf portion 107 of the quatrefoil communicates with the inlet hole 20 and the opposite leaf portion 108 communicates with the outlet hole 109 in the lower end plate 110. The other leaves 111, 112 are designed to accommodate both gears. In addition to the outlet holes 109, the lower end plate 110
It has a pressure equalization port 116 extending therein and communicating with a pressure equalization port 116 of the manifold block 15, and further includes a pressure equalization port 116 extending therein and communicating with a pressure equalization port 116 of the manifold block 15.
It has vertical holes 117 and 118 for housing and pivotally supporting the lower part of.

The bottom of the end plate 110 and the manifold block 1
A conventional "0" ring is provided between the top surface of the manifold block and the ring 122 of semicircular cross section on the top surface of the manifold block to form a seal between the two surfaces. There is.
There is no seal between the manifold and the storage chamber 13 other than this "O" ring. shaft 94
, 95, but this is not a problem as it is returned to the suction side of the pump through the T-shaped slot 123 in the manifold block.

As shown in FIG. 2, T-shaped slots 123 allow vertical holes 17 and 118 in the lower endplates to communicate with each other and with vertical holes 115 in the endplates.

Therefore, both rotating shafts 94, 95 and holes 117, 118
The leaking material flowing between the pump and the pump is returned to the suction side of the pump through the hole 115 in the end plate ]]0.
Pump 14 is attached to the top of the manifold block by bolts, not shown, that extend vertically through the vertical holes 26, 127.

In a recommended embodiment, spacer sleeves (not shown) are provided between holes 126, 127 and the bolts. Manifold block The manifold block 15 has a pump discharge port 1.
Holes are provided so that material discharged from 09 flows into vertical inlet holes 130 of the block.

This inlet hole 130 has a longitudinal passage 131. , a transverse passage 132, a longitudinal passage 133 on the front side of the block and outlet holes 134, 135. A conventional adhesive applicator, such as that shown in U.S. Pat. No. 27,865, republished, or U.S. Pat.
It is connected to outlet holes 134 and 135.

The number of outlet holes and the number of applicators connected thereto can be arbitrarily determined depending on the application.

A filter mounting hole 137 is provided coaxially with the longitudinal passage 131, and a normal filter can be inserted into the plug 138 at one end.
is housed by being screwed into the threaded end of the hole 137.

This filter is described in U.S. Patent No. 3,224,5
No. 90 (December 21, 1965) (shown here).
Crossing the longitudinal passageway 133, a reverse valve mounting hole 149 extends from the front face 150 of the manifold block to communicate with the pressure equalization port 116.

This inverted 6,1 stop valve mounting hole also intersects the longitudinal passageway at the front of the manifold. A conventional pressure release type one-way valve (check valve) (not shown) is provided in the hole 149 and is screwed into the hole 149. Pump Drive The pump 14 is driven by any type of drive motor. 165
and the drive shaft 166.

In the preferred embodiment shown in FIGS. 1-4, the motor drive shaft has a key 168 at its outer end that fits into a keyway 169 on the pump drive shaft. ing. The motor 165 is a pneumatically operated motor mounted on the cover 26 of the housing, and is rotated by compressed air, and its rotation rotates the shaft 166 at a constant speed via a reduction gear in the housing. ing.

This application is filed in U.S. Patent Application No. 549,1 by the same applicant.
No. 89 (U.S. Pat. No. 3,964,645) is a continuation-in-part of US Pat.

A feature of the present invention is that the material melted by the grid-type melting device 12 is prevented from flowing backward into the hopper. Such a backflow occurs when the amount melted by the grid-type melter 12 exceeds the amount consumed by the coating device 22.

To prevent this, a shroud 29 is provided above and spaced from the bottom outer wall of the hopper to define an air chamber 200.

Air is continuously fed into this air chamber 200 during operation of the device 5, and this air flow is provided to the tube 32 of the hopper 11 by the molten thermoplastic material rising from the melting device 12. A larger amount of heat than the amount of heat is removed from the outer wall of the tube. The cold wall 32 of the hopper thus acts as a thermal barrier to prevent molten material from flowing back up into the hopper. Shroud 29 has a base 201 and an upper portion 202.

The base is separated outwardly from the vertical wall 32 of the hopper by four side walls, a lower flange 203 and an upper flange 20.
1. The lower flange 203 protrudes outward from the bottom surface of the base 201 and rests on the gasket retaining plate 55. The upper part 202 of the shroud also has four vertical walls spaced outwardly from the hopper wall 32 and a lower flange 205 and an upper flange 206.
A lower flange extends inwardly from the sidewall of the top 202 and rests on the outwardly projecting flange 204 of the bottom 201 . The upper flange 206 of the upper portion 202 extends inwardly to contact the outer surface of the hopper sidewall 32. In the preferred practical example, the lower part 201 of the shroud is connected to the top part 202 by bolting or other means;
It is also secured to the top of the grate melter by conventional bonding devices (not shown).

The hopper 11 is pushed into the shroud until the hopper flange 35 and the shroud upper flange 206 abut.

The flange 35 is usually not fixed to the shroud,
The hopper can therefore be easily removed from the shroud by simply pulling upwards. In the embodiment shown in FIGS. 1-4, a conventional electric fan 210 is mounted in the top 202 sidewall 211 of the shroud 29 to create a flow of pressurized air into the shroud during operation of the apparatus and to direct the air into the shroud. It is pushed out from an orifice 212 provided in the lower part 201 of the.

The material of the side wall 32 of the hopper 11 is fan 210.
Preferably, aluminum is used to provide better heat transfer to the air stream.

If the air flow prevents free zinc crosslinking of the molten material in the hopper, the chamber 200
The air flow therein must be capable of removing heat at a rate greater than the rate at which heat is imparted to the sidewalls 32 by the flowing molten material. By constructing the side wall of the hopper from aluminum, this heat removal is facilitated. A second preferred embodiment of the device for preventing backflow from the grate melter 12 to the bottom of the hopper 11 is shown in FIG.

In this example, the upper end of the wall 32 of the hopper 11 is attached to the upper end of the shroud 220 by means such as welding. In this example, the inner surface of the shroud and the hopper 11
The flow of air between the outer wall of the chamber 221 is accomplished by connecting the exhaust of the air motor 165 to the chamber 221 via a conduit 222 without using the fan 210.

The exhaust air then flows through the chamber upwardly over the outer wall 32 and exits through holes 223 provided in the shroud.

Motor 165 is operated by compressed air.

As the compressed air exits through the motor outlet, conduit 222, it expands at a rapid rate as it enters the cooling chamber 221 where it cools to a temperature of about 0 DEG or less. Thus, the wall 32 of the hopper 11 is continuously cooled by the exhaust from the motor 165. FIG. 6 shows a third embodiment in which the one shown in FIG. 5 is further modified.

In this example, exhaust from motor 165 flows into cooling chamber 221 and at least a portion of the air from conduit 222 flows into cooling tube 225. The tube 225 extends between and is attached to the side walls 32 of the hopper 11. This tube is located directly in the path of the airflow discharged from conduit 222 into chamber 221;
A large portion of the air will therefore flow through this tube, and this cool air stream will absorb heat from the solid thermoplastic material below the hopper and the tube and the wall of the hopper connected thereto. A major advantage of the present invention is the formation of a solid barrier between the inner walls of a supply hopper in a thermoplastic material melting apparatus, i.e., crosslinking (B
The key point is to eliminate rdging.

By preventing melt from flowing back into the hopper, it is possible to prevent the supply from being temporarily disabled due to the solid barrier of the feed in the hopper when the equipment is reused after a temporary suspension. be done. Although the content of the present invention has been explained above through three embodiments, it will be obvious to those skilled in the art that various modifications and variations can be made to the present invention within the scope of the claims. .

[Brief explanation of drawings]

FIG. 1 is a perspective view of an apparatus for melting a thermoplastic material and making it available for use, which is an embodiment of the present invention, and FIG. 2 is an exploded perspective view of a part of the apparatus shown in FIG. 1. , FIG. 3 is a side elevational view with a part of the device shown in FIG. 1 removed, FIG. 4 is a sectional view taken along line 4-4 in FIG. 3, and FIG. 5 is another embodiment. FIG. 6 is a sectional view similar to FIG. 5 showing another embodiment, and FIG. 7 is a sectional view taken along line 7-7 in FIG. 6. be. Each reference numeral in the figure indicates the following. 10... Housing, 1]...
... hopper] 2...Grate type melting device, 13...Storage room, 14...
... Pump, 15... Manifold block, 16... Bottom opening of melter, 22
...... Equipment for making materials available for use (adhesive applicator), 29... Shroud, 61...
・・・・・・Heating heater, 210・・・・・・・・・
Cooling fan.

Claims (1)

Claims: 1. An apparatus for converting a solid thermoplastic material into a molten thermoplastic material and providing the molten thermoplastic material for use, comprising at least a housing having a hopper for receiving the solid thermoplastic material; a grate-type melting device that has one discharge opening and is provided below the hopper and allows flow through;
a storage chamber provided below the grid-type melter and adapted to receive molten material discharged from the discharge opening; a device for heating the melter; and a device for bringing the molten thermoplastic material into use. a pump for supplying the molten thermoplastic material from the storage chamber to the service apparatus; and a pump for supplying the molten thermoplastic material from the grate melter upstream into the hopper. a backflow prevention device for preventing the backflow; the shroud defining an air chamber between it and the outer wall of the hopper;
and a device for supplying a forced air flow into the air chamber to cool the lower part of the hopper. 2. The method of claim 1, further comprising a flexible seal extending between an inner wall of the shroud and an outer wall of the hopper, the seal being located proximate the bottom of the hopper. The device described. 3. The device of claim 2, wherein the device for providing airflow includes a motor-driven fan mounted to the wall of the shroud. 4. an air-operated motor for driving the pump, the air-operated motor having an inlet hole and an exhaust hole communicating with a source of pressurized air, and a device for supplying the air flow that connects the motor to the pump. 3. The device of claim 2, further comprising a conduit communicating an exhaust hole with the air chamber. 5. The device of claim 1, wherein the device for providing airflow includes a motor-driven fan mounted to the wall of the shroud. 6 comprising an air-operated motor for driving said pump, said air-operated motor having an inlet communicating with a source of pressurized air, and an exhaust hole, said device for supplying said air flow said air-operated motor; and a conduit communicating with the air chamber. 7. Apparatus according to claim 1, characterized in that the hopper is made of aluminum. 8. In an apparatus for converting a solid thermoplastic material into a molten thermoplastic material and providing said molten thermoplastic material for use,
A flowable grate melting device having a housing having a hopper for receiving a solid thermoplastic material, a continuous side wall, a bottom wall, and an open top for receiving the solid thermoplastic material from the hopper. a lattice-type melting device, wherein the bottom wall has a plurality of divided compartments, each compartment having an upper part and a lower part, and an upper part of each compartment having a truncated conical shape; at least one discharge opening provided in the melting device; a storage chamber provided below the grid-type melter and adapted to receive a supply of molten material from the discharge opening; a heating device for heating said bottom wall; a serving device adapted to put said molten thermoplastic material into use; and a serving device adapted to convey said molten thermoplastic material from said storage chamber to said serving device. a pump and a backflow prevention device configured to prevent the molten material from flowing back upstream from the grid-type melting device to the hopper; a shroud enclosing a lower portion, the shroud defining an air chamber between an inner wall of the shroud and an outer wall of the hopper, and the backflow prevention device also having an air flow supply device. an apparatus for melting and preparing solid thermoplastic materials, wherein the air flow supply device supplies a forced air flow into the air chamber to cool the lower part of the hopper. . 9. The apparatus of claim 8, wherein a flexible seal is provided adjacent the lower portion of the hopper between the inner wall of the shroud and the outer wall of the hopper. 10. The apparatus of claim 8, wherein the air flow supply device includes a motor-driven fan disposed in a wall of the shroud. 11 a pneumatically actuated motor for driving said pump, said pneumatically actuated motor having an inlet communicating with a source of pressurized air and an exhaust hole, and a device for supplying said air flow said pneumatically actuated motor; 9. The apparatus of claim 8, including a conduit communicating between the motor and the air chamber. 12. A semiconductor device disposed in the hopper, the conduit device being disposed in the path of air flow from one end of the conduit communicating the air operated motor and the air chamber. The device according to item 11 above. 13. The apparatus according to item 11, having a semiconductor device in the hopper and supported by the hopper. 14. The device according to item 13, wherein the hopper and the semiconductor device are made of aluminum.