Method for manufacturing a product of thermoplastic resin and/or thermoplastic elastomer

The object of the present invention is to provide a method for manufacturing a product of thermoplastic resin and/or thermoplastic elastomer with materials of high recycle capability, preventing the productivity drop and the cost increase as well as the damage caused by the contact between semi-finished products and a drawing machine. A plurality of semi-finished moles and a drawing element are molded integrally by an extruder. The semi-finished moles are separated from the drawing element by cutting. The semi-finished moles separated from the drawing element are cut in accordance with a given length to produce a mole.

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing a product of thermoplastic resin and/or thermoplastic elastomer, which is used for interior and exterior moldings, and door and body seals.

The parts manufactured by extrusion such as interior and exterior moldings and door and body seals include; a door molding, an inner weather strip, a drip molding, a window molding, a roof molding, an opening trim, an opening seal, a trunk lid seal, a tail gate seal, a door seal and a run channel. As an example, the part such as shown inFIG. 12has been manufactured conventionally. A molding110has been manufactured with a metallic core111made of aluminum alloy or stainless steel, to which a seal112made of a PVC material of thermoplastic resin or an EPDM material of rubber or thermoplastic elastomer and a decorative surface113are integrally molded by extrusion molding. An elastomer is an elastic resin like rubber and a thermoplastic elastomer is a rubber-like molding material which can be molded by the remelt treatment. And a thermoplastic resin is an inelastic resin which can be molded by the remelt treatment.

The process for manufacturing the mold mentioned above is shown in FIG.13. At an extrusion step S10, a metallic core material M, a lip material L and a decorative material D, which are composed of a PVC material of thermoplastic resin, are supplied to an extruder120where an extrusion molding is performed. A semi-finished molding115is manufactured and is supplied to a cooling step S20. At the cooling step S20, the semi-finished molding115is cooled down passing through a cooling chamber121. At a drawing step S30subsequent to the cooling step S20, the semi-finished molding115is drawn with the rotation of a drawing machine122. Drawing by the drawing machine122gives the drawing force to the semi-finished molding115at the cooling step S20.

The semi-finished molding115is supplied to a dimension measurement step S40from the drawing step S30and measured up. And at a cutting step S50, the semi-finished molding is cut in accordance with the required length measured at the dimension measurement step S40by a cutting machine124to produce a molding110, which is stored in a container125.

The molding110including the metallic core111made of a metal, to which the seal112and the decorative surface113made of the thermoplastic resin are integrally molded, is difficult to be recycled, thereby giving rise to environmental pollution caused by poisonous gasses when it is incinerated. The part made of olefinic material thoroughly has been recently introduced, in which a core is also made of thermoplastic resin, so that the core can be recycled. This type of part can be manufactured by the same process as that shown in FIG.13.

However, manufacturing of the thorough olefinic parts has been suffered from the following problems.

The rupture, the surface waviness and the rough surface of the core will possibly occur if the part of thorough olefinic material is manufactured under the same extrusion speed as that of the part with a metallic core. In order to prevent the problems such as surface waviness, the extrusion speed must be slowed down to approximately one fifth of that applied to the manufacturing of the part with a metallic core. It will lower the productivity, thereby giving rise to the remarkable cost increase. If the parallel operation with plural extruders to compensate the productivity drop is introduced, more drawing machines are required for that.

The drawing machine has been possibly caused damage to the seal or the decorative surface of the molding since the drawing machine requires interposing the molding for drawing. It is possible to lower the interposing force of the drawing machine in order not to cause damage on the seal or the decorative surface of the molding, though another problem could occur that the slipping due to the resultant decrease in the drawing force renders the drawing machine inoperable.

SUMMARY OF THE INVENTION

The object of the present invention to assess the problems is to provide a method for manufacturing a product of thermoplastic resin and/or thermoplastic elastomer with materials of high recycle capability, preventing the productivity drop and the cost increase as well as the damage caused by the contact between the semi-finished products and the drawing machine.

The invention to assess the problems described above provides a method for manufacturing a product of thermoplastic resin or thermoplastic elastomer, or a hybrid product of thermoplastic resin and thermoplastic elastomer, the method comprising the steps of: molding integrally a plurality of semi-finished products and a drawing element by extrusion, which comprise thermoplastic resin or thermoplastic elastomer, or a hybrid of thermoplastic resin and thermoplastic elastomer; separating the plurality of semi-finished products from the drawing element by cutting in a drawing direction; drawing the drawing element separated from the plurality of semi-finished products by a drawing machine, thereby continuing to draw the plurality of semi-finished products and the drawing element which are before separation; and cutting the plurality of semi-finished products at a given length from which the drawing element has been separated.

The invention according to claim1provides a method of manufacturing a product by molding the plural semi-finished products and the drawing element integrally, thereby obviating the productivity drop even if the extrusion speed is lowered.

When the semi-finished products are drawn at the previous stage of manufacturing the finished product, the drawing element, which is molded integrally with the semi-finished product, is drawn by the drawing machine. The semi-finished products are not required to be in contact with the drawing machine, which will obviate the damage caused by the contact with the drawing machine.

The invention according to claim2provides the method for manufacturing a product of thermoplastic resin or thermoplastic elastomer, or a hybrid product of thermoplastic resin and thermoplastic elastomer according to claim1, wherein the plurality of semi-finished products and the drawing element comprise an olefinic material.

The invention according to claim2employs the olefinic materials—desirable for recycling-both for the semi-finished products and the drawing element. Therefore, the recycling of the product can be conducted properly when it is scrapped. Also, the drawing element can be reused for the material of extrusion molding repeatedly not scrapped.

The invention according to claim3(or4) provides the method for manufacturing a product of thermoplastic resin or thermoplastic elastomer, or a hybrid product of thermoplastic resin and thermoplastic elastomer according to claim1(or2), wherein the thickness of connecting elements for connecting the plurality of semi-finished products and the drawing element is from no less than 0.5 mm to no more than 10 mm.

If the thickness of the connecting elements between the semi-finished products and the drawing element is less than 0.5 mm, the semi-finished products and the drawing element tend to separate accidentally. On the contrary, if it is more than 10 mm, it may possibly be time-consuming to separate the semi-finished products from the drawing element. It is the reason why the invention according to claim3specifies the range of no less than 0.5 mm to no more than 10 mm for the thickness of the connecting elements. This range of thickness will prevent the accidental separation of the product material from the drawing element and render the cutting easier at the separation step.

The invention according to claim5, (6,7or8) provides the method for manufacturing a product of thermoplastic resin or thermoplastic elastomer, or a hybrid product of thermoplastic resin and thermoplastic elastomer according to claim1, (2,3or4), wherein the plurality of semi-finished products are oriented facing in a common direction.

When the product has a surface sliding on the glass, hair transplanting is sometimes made on it. In case the sliding surface where the hair transplanting is made is on one surface of the product, the semi-finished products need to be oriented in a given direction. The invention according to claims5through8eliminates a step to rotate the semi-finished products to align the sliding surfaces, since the semi-finished products face in a common direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiment of the present invention will now be described referring to the accompanying drawings.

FIG. 1is a sectional view showing a molding of thermoplastic resin and thermoplastic elastomer according to the present invention.

The method for manufacturing a molding1such as a door molding, which has the cross section shown inFIG. 1, will be described. The molding1is a long product, which is cut out from a semi-finished molding manufactured by extrusion, including a core2, a lip3and a decorative surface4. The core2is made of PP (polypropylene) of thermoplastic resin, which has some degree of hardness and stiffness. On the other hand the lip3and the decorative surface4are made of TPO (thermo plasticelastomer olefin) resin of thermoplastic elastomer, which have elasticity. The core2, the lip3and the decorative surface4are all made of the olefinic materials of thermoplastic resins, which are desirable in terms of recycling.

The molding1shown inFIG. 1is cut out from the long semi-finished molding manufactured by extrusion. In this embodiment, the four of the same shape semi-finished moldings are manufactured simultaneously. The plural semi-finished moldings are integrally molded connected to a drawing element with respective connecting elements (the whole part including the semi-finished molding connected to the drawing element with the connecting elements hereinafter referred to as extrusion molded part).

Before the description of the manufacturing process, an example of the position of the semi-finished moldings and the drawing element of an extrusion molded part will be described referring to FIG.2. An extrusion molded part10has four semi-finished moldings11-14, which are simultaneously extruded. As shown inFIG. 2, the four semi-finished moldings11-14of the extrusion molded part10have the same shape and are oriented so that they face in a common direction vertically: each of sliding surfaces5of the lips3is oriented upward, which is slidably in contact with a glass when mounted on a vehicle. The four semi-finished moldings11-14are connected to a drawing element19with connecting elements15-18, respectively. Each of the connecting portions between the semi-finished moldings11-14and the connecting elements15-18is located so that it may not interfere with the decorative surface4(see FIG.1). Therefore, the surface4can be kept free of damage, even if the separating surfaces between the semi-finished moldings11-14and the connecting elements15-18become rough or irregular at the separation.

It is preferred that the thickness of the connecting elements15-18be set in the range of no less than 0.5 mm to no more than 10 mm. If it is less than 0.5 mm, it is probable that the connecting element15-18will break. On the other hand, if it exceeds 10 mm, the big force is required for cutting off the connecting elements15-18.

The drawing element19is approximately rectangle, from the upper surface of which the first and fourth connecting elements15and18extend to be connected to the ends of the cores of the first and fourth semi-finished moldings11and14, respectively. On the other hand, the second and third connecting elements16and17extend diagonally downward from the lower corners of the drawing element19and are connected to the ends of the cores of the second and third semi-finished moldings12and13. The semi-finished moldings11-14are oriented around the drawing element19so that the envelope falls in a circle shown with the dotted line in FIG.2. If the four connecting elements are aligned in a line, it will require increasing of the inner diameter and the effective diameter of an extruder, which necessitates an extruder with a bigger mouthpiece. The above mentioned positioning of a near circle is preferable in order to obviate the need for such a big extruder.

When the plural semi-finished moldings are manufactured in parallel, the existing mouthpiece which has been employed conventionally will still be competent without modification, since the near circular positioning of the semi-finished moldings11-14doesn't necessitate a big mouthpiece. Also the semi-finished moldings11-14are subjected to the uniform extrusion pressure by positioning them in a near circle. Thus the shape of the manufactured molding can be stabilized.

The process of manufacturing the moldings shown inFIG. 1from the extrusion molded part shown inFIG. 2will be described referring to FIG.3. As shown inFIG. 3, at an extrusion step S1the extrusion molded part10is extrusion molded by an extruder20. A core material B of PP, a lip material L and a decorative material D of TPO are supplied to the extruder20. The extruder20molds the extrusion molded part10with these materials by the extrusion molding.

The extrusion molded part10molded at the extrusion step S1is carried to a cooling step S2. At the cooling step S2, the extrusion molded part10is cooled down to an appropriate temperature passing through a water tank21.

The extrusion molded part10cooled down at the cooling step S2is carried to a separation step S3. At the separation step S3, a separation unit22is provided, which is for separating the semi-finished moldings11-14from the drawing element19. The separation unit22comprises the physical cutting means such as a cutter or the melt cutting means such as a heat coil. The four semi-finished moldings11-14are cut off from the drawing element19by the separation unit22. Subsequently, the semi-finished moldings11-14are carried to a dimension measurement step S5and the drawing element19is carried to a drawing step S4. A drawing machine23for drawing the drawing element19is prepared at the drawing step S4. The drawing machine23has an upper conveyer23A and a lower conveyer23B, both of which interpose the drawing element19to draw it by the rotation of the upper and lower conveyers23A and23B.

When the drawing machine23draws the drawing element19, the upper and lower surfaces of the drawing element19are preferably flat, since the upper and lower conveyers23A and23B interpose the drawing element19pressing it vertically. Only by separating the semi-finished moldings11-14from the connecting elements15-18, the connecting elements15-18remain projecting from the upper and lower surfaces of the drawing element19. It is thereby difficult to interpose the drawing element19by the upper and lower conveyers23A and23B. Therefore, at the separation step S3, the connecting elements15-18are separated from the drawing element19as well as the semi-finished moldings11-14from the connecting elements15-18. The upper and lower surfaces of the drawing element19is rendered flat by separating the connecting elements15-18, thereby allowing the upper and lower conveyers23A and23B to interpose the drawing element19securely. As a result, the drawing element19can be drawn stably; thereby the extrusion molded part10as well.

The drawing machine23, which draws the drawing element19, gives the continuous drawing force to the semi-finished moldings11-14and the extrusion molded part10. The semi-finished moldings11-14are not interposed by the drawing machine23under the pressing force, thereby free from the damage. So the drawing machine23can interpose the drawing element19with relatively large force, for it is not necessary to decrease the interposing force. Therefore, the drawing machine23can prevent the slip between the drawing machine23and the drawing element19.

The four semi-finished molding11-14separated from the drawing element19at the separation step S3are carried to the dimension measurement step S5. At the dimension measurement step S5a dimension measurement unit24is prepared to measure the semi-finished moldings11-14for cutting and carry them to the following cutting step S6. At the cutting step S6, a cutting machine25is prepared, which cuts the semi-finished moldings11-14according to the dimension measured at the dimension measurement step S5to produce the molding1. The manufactured molding1is stored in a container26.

By manufacturing the molding1with the extrusion molded part10, which includes the plural semi-finished moldings11-14, the reduction in the productivity will be restrained even if the extrusion speed is slowed down compared with the case in which a metallic core is employed. Therefore, the products such as recycling adaptable moldings can be manufactured obviating the productivity drop. The existing extruder which has been used hitherto is competent for the extruder20, since the large mouthpiece of an extruder is rendered unnecessary by orienting the semi-finished moldings11-14in a circle envelope.

The drawing operation can be performed so that the drawing machine23may not be in contact with the semi-finished moldings11-14, since the drawing machine draws the whole extrusion molded part10interposing only the drawing element19, to which the semi-finished moldings11-14are connected. Therefore the semi-finished moldings11-14are free from the damage caused by the drawing machine23coming into contact with the semi-finished moldings11-14. Each of the semi-finished moldings11-14is so oriented that sliding surfaces5(seeFIG. 1) see upward. A step to turn around the semi-finished moldings11-14can thus be omitted when a treatment such as the hair planting is given to the sliding surfaces5.

Next, another example of an extrusion molded part, to which the method for manufacturing a product of thermoplastic resin and thermoplastic elastomer according to the present invention is applied, will be described referring to FIG.2. Each shape of the following extrusion molded parts can be molded by modifying the shape of the mouthpiece for the extruder20.

FIG. 4is a cross sectional view showing the extrusion molded part according to the second embodiment.

As shown inFIG. 4, an extrusion molded part30has four semi-finished moldings31-34, which have the same shape and are connected to a drawing element39with connecting elements35-38, respectively. Each of the semi-finished moldings31-34is oriented so that the sliding surfaces5see upward in the extrusion molded part30. The drawing element39has the cross section of trapezoid, from the upper surface of which the connecting elements35and38extend to be connected to the upward semi-finished moldings31and34. The connecting elements36and37, which extend sideward from the lower portions of the sides of the drawing element39, are connected to the downward semi-finished moldings32and33. The molding1according to the second embodiment is also manufactured in accordance with the process flow shown in FIG.3. In the extrusion molded part30, the semi-finished moldings31-34are positioned better balanced since they are positioned as described above around the drawing element39of a trapezoidal cross section. Therefore, the high stability of extrusion shape by the extruder20can be maintained. When the drawing machine23interposes the drawing element39vertically at drawing, the connecting elements36and37will be of no interference even if they remain on the drawing element39, since they extend sideway from the drawing element39. Therefore, at the separation step S3the drawing machine23can perform the secure drawing interposing the drawing element39even if the separation of the downward connecting elements36and37from the drawing element39is omitted.

FIG. 5is a cross sectional view showing the extrusion molded part according to the third embodiment.

As shown inFIG. 5, an extrusion molded part40has four semi-finished moldings4144, which have the same shape and are connected to a drawing element49with connecting elements45-48, respectively. The four semi-finished moldings4144are oriented symmetrical in both vertical and horizontal directions relative to a drawing element49. The semi-finished moldings41-44are accordingly oriented better balanced in the extrusion molded part40than those in the molding extrusion molded parts10and30, which results in the better stability of molding of the extrusion molded part40by the extruder20.

FIG. 6is a cross sectional view showing the extrusion molded part according to the fourth embodiment.

As shown inFIG. 6, an extrusion molded part50has four semi-finished moldings51-54, which have the same shape and are connected to a drawing element59with connecting elements55-58, respectively. The four semi-finished moldings51-54are oriented symmetrical in both vertical and horizontal directions relative to a drawing element59. The high stability of extrusion molding by the extruder20is also attained like the third embodiment described before.

The drawing element59has the cross section of hexagon, the top and bottom sides of which are slightly longer than the remaining sides. The top ends of the connecting elements55and58, which connect the upward semi-finished moldings51and54to the drawing element59, stand lower than the top surface of the drawing element59. On the other hand, the bottom ends of the connecting elements56and57, which connect the downward semi-finished moldings52and53to the drawing element59, stand higher than the bottom surface of the drawing element59.

The connecting elements55-58will not go over the top or bottom surface of the drawing element59even if the connecting element55-58are not separated from the drawing element59at the separation of the semi-finished moldings51-54. The semi-finished moldings51-54may thus be separated from the connecting element55-58respectively leaving the connecting element55-58on the drawing element59at the separation step S3shown in FIG.3.

At the subsequent drawing step S4, the drawing machine23adds the drawing force to the drawing element59interposing it vertically with the upper and lower conveyers23A and23B. When the drawing machine23interposes the drawing element59vertically, the connecting elements55-58will be of no interference, since they stand receding from the top or bottom surface of the hexagonal cross section of the drawing element59as shown in FIG.6. Therefore, the extrusion molded part50according to the fourth embodiment can be manufactured obviating the operation, in which the connecting elements55-58are separated from the drawing element59.

FIG. 7is a cross sectional view showing the extrusion molded part according to the fifth embodiment.

As shown inFIG. 7, an extrusion molded part60has four semi-finished moldings61-64, which have the same shape and are connected to a drawing element69with connecting elements65-68, respectively. The drawing element69has the cross section of long sideways rectangle. The connecting elements65-68extend from the both ends of top and bottom surfaces. In the extrusion molded part60according to the fifth embodiment, the stability of extrusion shape by the extruder20can be attained, since the four semi-finished moldings61-64are oriented horizontally symmetrical relative to the drawing element69.

The drawing element69is designed so that its cross section has the shape of long sideways rectangle. Running the upper conveyer23A between the upward connecting elements65and68, and the lower conveyer23B between the downward connecting elements66and67, the drawing machine23can interpose the drawing element69at the drawing step S4, even if the connecting elements65-68are not separated from the drawing element69. The drawing machine23can thus interpose and draw the drawing element69securely only by separating the semi-finished moldings61-64from the connecting parts65-68respectively, obviating the separation of the connecting parts65-68from the drawing element69.

FIG. 8is a cross sectional view showing the extrusion molded part according to the sixth embodiment.

As shown inFIG. 8, an extrusion molded part70has three semi-finished moldings71-73, which have the same shape and are connected to a drawing element77with connecting elements74-76, respectively. The drawing element77has the cross section of rectangle. The connecting elements74and76extend upward from the top surface of the drawing element77, and the connecting element71downward from the bottom surface. The sixth embodiment provides the extrusion molded part70, by which manufacturing of three semi-finished moldings71-73in parallel can be effected.

The sides of the drawing element77are flat and the connecting elements74-76stay out of the side regions. The operation of separating the connecting elements74-76from the drawing element77at the separation step S3can be omitted if a drawing machine which has the right and left conveyers to interpose the drawing element77is introduced instead of the drawing machine23.

FIG. 9is a cross sectional view showing the extrusion molded part according to the seventh embodiment.

As shown inFIG. 9, an extrusion molded part80has two semi-finished moldings81and82, which have the same shape and are connected to a drawing element85with connecting elements83and84, respectively. The drawing element85has the cross section of rectangle, from the top surface of which the connecting elements83and84extend upward to be connected to the semi-finished moldings81and82. The seventh embodiment provides the extrusion molded part80, by which manufacturing of two semi-finished moldings81and82in parallel can be attained.

Both sides of the drawing element85are flat and the connecting elements83and84stay out of the side regions. The operation of separating the connecting elements83and84from the drawing element85at the separation step S3can be omitted if a drawing machine which has the right and left conveyers to interpose the drawing element85is introduced instead of the drawing machine23.

FIG. 10is a cross sectional view showing the extrusion molded part according to the eighth embodiment.

As shown inFIG. 10, an extrusion molded part90has four semi-finished moldings91-94, which have the same shape and are connected to a drawing element99with connecting elements95-98, respectively. The disposition of the extrusion molded part90is the same as that of the third embodiment shown inFIG. 5. Abridge100connects the upward semi-finished moldings91and94, and a bridge101connects the downward semi-finished moldings92and93. These bridges reinforce the strength of the combination of the semi-finished moldings91and94, and the semi-finished moldings92and93, respectively.

In the preparation of drawing the semi-finished moldings91-94by the drawing machine23, the bridges100and101are separated from the semi-finished moldings91-94at the separation step S3. Subsequently the connecting elements95-98are separated from the drawing element99, and the semi-finished moldings91-94are cut out from the connecting elements95-98, respectively. This will complete the separation at the separation step S3.

A connecting element with reduced portions can also be employed instead of the uniform connecting element in the embodiments described above.FIG. 11Ais an enlarged view showing the connecting element shown in FIG.2andFIG. 11Bis an enlarged view showing the connecting element with reduced portions.

As shown inFIG. 11B, a connecting element16′ with reduced portions has a main portion16A with reduced portions16B and16C at both ends. Providing the reduced portions, the stiffness of the whole extrusion molded part can be attained and the force required for the separation can be reduced as well.

In the case of the uniform connecting elements16and17shown inFIG. 11A, the thickness of no less than 0.5 mm to no more than 10 mm is appropriate as described before. On the other hand, when the reduced portions16B,16C,17B and17C are provided as shown inFIG. 11B, their thickness of no less than 0.5 mm to no more than 10 mm will be desirable.

It goes without saying that the connecting element according to other embodiments can also have reduced portions.

It will now be appreciated from the foregoing description that the present invention is not limited to the particularly illustrated embodiment discussed above and may be carried out in various modified forms. In the embodiments described above, the descriptions have been made typically for the molding as a product, though the method can be applied to other products such as seals. In the above-mentioned embodiments, a connecting element is prepared for each semi-finished molding, which is for connecting a drawing element and a semi-finished molding. Two connecting elements or more can be provided for a semi-finished molding. The molding according to the embodiments described above is a product of both thermoplastic resin and thermoplastic elastomer. The present invention can also be applied to other products such as a product of thermoplastic resin only or a product of thermoplastic elastomer only.