JP3700760B2 - Hot plate welding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for welding resin molded products using a hot plate, and more particularly to a hot plate welding method for welding molded products made of different kinds of resins having different melting points using a hot plate.
[0002]
[Prior art]
Resin-molded products are used in various fields because they have the characteristics of being inexpensive and lightweight without corrosion like metals and wood. Also, in order to save earth resources by recycling, most of the resin molded products are formed from thermoplastic resins. Various molding methods such as compression molding, transfer molding, injection molding, extrusion molding, and blow molding are used. Due to advances in molding machines and mold structures, complex shaped resin molded products can be easily molded. Yes.
[0003]
However, it may still be difficult to manufacture a molded product having a complicated shape by a single molding. In many cases, it is necessary to form a part of the molded product from a different kind of resin. In such a case, a plurality of molded products are respectively molded and then integrated by welding.
[0004]
The welding of the resin molded product is performed by heating the bonding surfaces of a pair of molded products to be welded, pressure-bonding them in a state where at least one of the bonding surfaces is melted, and cooling in that state. As a method for heating the bonding surface, a method using a heated hot plate, a method in which a pair of molded products are vibrated in a state where they are pressed and heated by frictional heat, etc. are known. This is called the welding method. Moreover, the method of vibrating using ultrasonic vibration is also called ultrasonic welding.
[0005]
Among them, the hot plate welding method is a method in which a bonding surface of a pair of molded products to be welded is brought into contact with and melted on the surface of the hot plate heated above the softening point of the molded product. In this method, the bonding surfaces of the molded product are pressure-bonded and cooled in that state. This hot plate welding method is particularly widely used because it has simple equipment and can be easily welded.
[0006]
[Problems to be solved by the invention]
However, when moldings formed of resins having different melting points are to be welded using the hot plate welding method, a problem may occur. For example, when two molded products having a large difference in melting point are to be welded, the temperature of the hot plate must be heated above the melting point of the molded product having a higher melting point. May be melted to other than the bonding surface of the molded product having a lower melting point, or may be softened and deformed even if not melted.
[0007]
Even if the difference in melting points is small, a problem may occur. For example, when trying to weld a nonwoven fabric made of thermoplastic resin fibers having a low melting point to an opening of a cylindrical molded product made of a thermoplastic resin having a high melting point so as not to impair the air permeability, the nonwoven fabric side should not be melted. In addition, it is desirable that the peripheral edge of the opening of the molded product is melted and the non-woven fabric is impregnated with the molten resin for welding. In this case, if the nonwoven fabric side is not heated to some extent, the molten resin is cooled and impregnation may be insufficient, resulting in poor bonding. However, when heated by a conventional hot plate welding method, the nonwoven fabric side melts. There is a problem that air permeability is impaired.
[0008]
In order to solve such a problem, for example, it is necessary to perform welding as shown in FIG. In FIG. 3, the hot plate A and the hot plate B are formed in a sandwich shape with the heat insulating plate 100 sandwiched therebetween, and the hot plate B is heated so as to have a higher temperature than the hot plate A. The hot plate A is brought into contact with a molded product 200 made of a low melting point resin, and the hot plate B is brought into contact with a molded product 300 made of a high melting point resin. If it does in this way, the above malfunctions can be prevented by selecting the heating temperature of the hot plate A and the hot plate B suitably.
[0009]
However, the above method requires two hot plates. Although it is possible to set the surface temperature separately with a single hot plate, the size of the hot plate increases. Furthermore, in order to control the temperature of the hot plate, a sensor and a temperature controller are required. Therefore, there is a problem that the welding machine becomes large and costs are increased, and restrictions on the arrangement space are large.
[0010]
The present invention has been made in view of such circumstances, and an object of the present invention is to be able to weld resin molded products having different melting points with a single hot plate at a low cost without increasing the size of the welding machine. And
[0011]
Another object of the present invention is to weld a nonwoven fabric made of thermoplastic resin fibers to a molded article having a melting point higher than that of the nonwoven fabric at a low cost without impairing the breathability of the nonwoven fabric.
[0012]
[Means for Solving the Problems]
The hot plate welding method of the present invention that solves the above problem is characterized in that a first molded product made of a first resin and a second molded product made of a second resin having a higher melting point than the first resin are used by using a hot plate. It is a method of welding, heating the contact surface of the second molded product in contact with one surface of the hot plate heated to the melting point of the second resin or more, facing the other surface of the hot plate and separating from the other surface Then, the first molded product and the second molded product are heated in a state in which the joining surface of the first molded product is heated by radiant heat from the hot plate by disposing the first molded product and at least the joining surface of the second molded product is melted. It is to be welded by pressure bonding.
[0013]
Another hot plate welding method of the present invention is characterized in that, in the hot plate welding method, the first molded product is a cloth formed of fibers made of the first resin, and the bonding surface of the second molded product is melted. The resin is impregnated into the first molded product and welded.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the hot plate welding method of the present invention, the joining surface of the second molded product having a high melting point is heated in contact with the hot plate heated to the melting point or higher as in the conventional case, so that it is melted as in the conventional case. It can be welded. On the other hand, the first molded product having a low melting point is disposed at a certain distance from the hot plate, and the bonding surface of the first molded product is heated by the radiant heat from the hot plate. Since the radiant heat becomes smaller as the distance between the hot plate and the first molded product becomes larger, the heating state of the first molded product can be controlled arbitrarily by setting the desired distance, and deformation due to softening of the first molded product is prevented. It can be heated while welding. In this state, the hot plate is retracted, and the first molded product and the second molded product are crimped and cooled to complete the welding.
[0015]
If the first molded product is a cloth formed of fibers made of the first resin having a low melting point, the bonding surface of the first molded product is melted by heating the first molded product with radiant heat from a hot plate. Without heating and without deformation of the first molded product, it is possible to heat to the extent that the molten resin in which the joining surface of the second molded product is melted can be impregnated and welded. Therefore, the first molded product can be welded without impairing the air permeability. That is, since the second molded product can be formed into a cylindrical shape having an opening and the first molded product can be joined so as to cover the opening, it is possible to cover the opening while ensuring the air permeability of the first molded product. Become.
[0016]
The first resin and the second resin need only have a melting point of the second resin higher than that of the first resin, and there is no particular limitation on the difference between the melting points. Also, the first resin and the second resin are both thermoplastic resins, and any material that can be welded may be used as long as it is welded between ordinary molded products. Furthermore, there is no restriction | limiting in particular also in the shape of a 1st molded product and a 2nd molded product.
[0017]
The first molded article can be a cloth formed from fibers made of the first resin. Examples of the cloth include woven cloth, non-woven cloth, and knitted cloth. The degree of air permeability may be determined according to the purpose. Among these, a nonwoven fabric that is easy to manufacture is preferably used. When the first molded article is a cloth or a fiber assembly formed of fibers made of the first resin, the first resin may not be heat weldable to the second resin, and is melted between the fibers. If the second resin is impregnated and solidified, the first molded product and the second molded product can be joined by the anchor effect. This case is also included in the welding referred to in the present invention.
[0018]
The distance between the bonding surface of the first molded product and the hot plate is determined according to the temperature of the hot plate, the contact time between the second molded product and the hot plate, the melting point of the first resin, the ambient temperature, and the like. The heating time by radiant heat from the hot plate depends on the temperature of the hot plate, the contact time between the second molded product and the hot plate, the distance between the first molded product and the hot plate, the melting point of the first resin, the ambient temperature, etc. Can be decided. In general, the shorter the distance, the shorter the heating time, and the longer the distance, the longer the heating time.
[0019]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
[0020]
Incidentally, Japanese Patent Application Laid-Open No. 11-343938 discloses an air intake duct formed by heat compression molding from a nonwoven fabric containing thermoplastic resin fibers. By forming the intake duct from the nonwoven fabric molded body in this way, it is possible to effectively reduce intake noise. In addition, the publication describes that the following three reasons are considered as reasons for reducing the intake noise, and that the intake noise is considered to be reduced by a synergistic effect thereof.
(1) Since the nonwoven fabric is an elastic body, it has a vibration damping action, and the generation of sound waves due to vibration of the tube wall is suppressed.
(2) The sound wave that has entered a large number of gaps between the fibers of the nonwoven fabric is weakened due to the viscosity of the gaps and the effect of heat conduction, and the sound energy is attenuated due to the resonance of the fibers themselves as the sound pressure varies.
(3) Since at least a part of the tube wall has a certain degree of air permeability, the generation of a standing wave is suppressed by a part of the sound wave passing through the tube wall.
[0021]
However, since the nonwoven fabric molded body has a larger manufacturing man-hour than the general resin molded body and is expensive, there is a problem that the air intake duct formed from the nonwoven fabric molded body is extremely expensive as compared with the conventional air intake duct.
[0022]
Therefore, as a result of intensive research, the intake noise is the same even when the intake duct body is formed from a normal resin molded body, an opening is formed in a part of the pipe wall of the intake duct body, and the opening is covered with a nonwoven fabric. Was found to be reduced.
[0023]
The present embodiment is one of the steps for manufacturing such an intake duct, and performs a step of welding a nonwoven fabric to an opening provided in a part of the pipe wall of the intake duct body.
[0024]
1 and 2 show a hot plate welding machine used in this embodiment. The hot plate welding machine includes a base 1, a left slide block 2 and a right slide block 3 that are movably held on the base 1 to the left and right, a left receiving jig 4 that is held on the left slide block 2, The right receiving jig 5 held by the right slide block 3, the hot plate block 6 held so as to be movable back and forth in the vertical direction on the paper surface of FIGS. 1 and 2, and the hot plate fixed to the hot plate block 6 7.
[0025]
A rail 10 is fixed to the upper surface of the base 1, and the left slide block 2 and the right slide block 3 are guided by the rail 10 and are movable in the left-right direction. The left receiving jig 4 and the right receiving jig 5 are detachably held by the left slide block 2 and the right slide block 3 and face each other.
[0026]
Further, stoppers 40 and 50 protrude from the left receiving jig 4 and the right receiving jig 5 so as to face each other. Bolts 41 and 51 are respectively screwed to the tips of the stoppers 40 and 50, and the tips of the bolts 41 and 51 are in contact with the hot plate 7. The distance between the left receiving jig 4 and the right receiving jig 5 and the heat plate 7 can be adjusted by the screwing distance of the bolts 41 and 51 to the stoppers 40 and 50.
[0027]
Using the hot plate welding machine described above, welding is performed as follows.
[0028]
The left receiving jig 4 holds a felt 8 made of PET fiber having a melting point of 160 ° C. and molded into a predetermined shape. The distance between the surface of the felt 8 and the surface of the hot plate 7 is adjusted to 5 mm by the bolt 41.
[0029]
On the other hand, a cylindrical intake duct body 9 is held by the right receiving jig 5. The intake duct body 9 is formed by blow molding from PP having a melting point of 165 ° C., and a window 90 is formed in a part of the tube wall. The distance between the surface of the peripheral portion of the window 90 and the surface of the hot plate 7 is adjusted by the bolt 51 so that the peripheral portion of the window 90 is in contact with the hot plate 7.
[0030]
First, the felt 8 and the intake duct body 9 are held by the left receiving jig 4 and the right receiving jig 5 as described above, and the left slide block 2 and the right slide block 3 are moved away from each other. Next, the heating plate 7 is heated to 260 ° C. by energization and kept at a constant temperature, and the left slide block 2 and the right slide block 3 are moved toward each other. Then, the stoppers 40 and 50 are both brought into contact with the hot plate 7 so that the movement is restricted. In this state, the felt 8 and the intake duct body 9 are heated by the hot plate 7.
[0031]
Since the surface of the felt 8 is 5 mm away from the surface of the hot plate 7, it is heated by the radiant heat from the hot plate 7. On the other hand, since the peripheral edge of the window 90 of the intake duct body 9 is in contact with the hot plate 7, it is directly heated by the hot plate 7. When heated until the peripheral edge of the window 90 is sufficiently melted in this state, the felt 8 reaches about 100 ° C. and is not heated until it is softened, but is heated to a degree sufficient for welding.
[0032]
Then, the left slide block 2 and the right slide block 3 are slightly moved away from each other, and the hot plate block 6 is moved backward perpendicularly to the paper surface so that the hot plate 7 is moved to the left receiving jig 4 and the right receiving jig 5. Evacuate from between. Immediately, the left slide block 2 and the right slide block 3 are moved toward each other, and the felt 8 and the intake duct body 9 are pressure-bonded. The movement of the left slide block 2 and the right slide block 3 at this time is restricted by the front end of the bolt 52 that is screwed into the right slide block 5 and projecting against the surface of the left slide block 4. The crimping margin is determined by the protruding length.
[0033]
Accordingly, the molten resin at the peripheral edge of the window 90 is impregnated between the fibers of the felt 8, and the felt 8 is sufficiently warmed, so that the impregnated molten resin is prevented from being cooled. Therefore, the molten resin is sufficiently impregnated in the felt 8 and cooled in that state, whereby the felt 8 is firmly welded to the peripheral edge portion of the window 90 of the intake duct body 9.
[0034]
The felt 8 is welded to the peripheral edge of the window 90, and most of the felt 8 covers the opening of the window 90. Since the felt 8 was not heated until it softened, the felt 8 is maintained in a predetermined shape without being deformed, and a predetermined air permeability is maintained in a portion covering the opening of the window 90. Therefore, in the intake duct obtained by this embodiment, intake noise is effectively suppressed.
[0035]
In addition, when the material of the felt 8 is changed, it can respond easily by adjusting the screwing distance of the volt | bolt 41 and changing the distance with the hot platen 7. FIG.
[0036]
【The invention's effect】
That is, according to the hot plate welding method of the present invention, molded products having different melting points can be welded with a single hot plate, the welding machine can be small, and a small arrangement space is sufficient. Therefore, the manufacturing cost can be reduced.
[0037]
And if the present invention is used for welding the resin-made cucumber duct body and the resin nonwoven fabric, it is possible to weld the nonwoven fabric without impairing the breathability of the nonwoven fabric, and to produce an intake duct with reduced intake noise at a low cost. it can.
[Brief description of the drawings]
FIG. 1 is an overall front view of a hot plate welder used in an embodiment of the present invention.
FIG. 2 is an enlarged front view showing a state in which an object to be welded is heated with a hot plate using the hot plate welding machine used in one embodiment of the present invention.
FIG. 3 is a front view showing a conventional hot plate welding method and showing a state in which an object to be welded is heated with a hot plate using a conventional hot plate welding machine.
[Explanation of symbols]
1: base 2: left slide block 3: right slide block 4: left receiving jig 5: right receiving jig 6: hot plate block 7: hot plate 8: felt 9: intake duct body 40, 50: stopper

Claims (2)

A method of welding a first molded product made of a first resin and a second molded product made of a second resin having a higher melting point than the first resin using a hot plate,
The surface of the hot plate heated to a temperature equal to or higher than the melting point of the second resin is heated by bringing the bonding surface of the second molded article into contact with the surface of the hot plate, facing the other surface of the hot plate and spaced apart from the other surface. Heating the bonding surface of the first molded product by radiant heat from the hot plate by arranging the first molded product,
A hot plate welding method, wherein the first molded product and the second molded product are pressure-bonded and welded in a state where at least the joining surface of the second molded product is melted. The first molded article is a cloth formed of fibers made of the first resin, and the molten resin on the joining surface of the second molded article is impregnated into the first molded article and welded. The hot plate welding method according to claim 1.

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