The present invention relates to a method and apparatus for feeding a molten resin mass of a synthetic high molecular material. More specifically, the invention relates to a method and apparatus for feeding a molten resin mass for causing a predetermined amount of the molten resin extruded from a die head of an extruder to fall down into a female mold for compression molding.
An injection-molding method and a compression-molding method have heretofore been widely known for producing such containers as bottles, caps and cups by using thermoplastic resins. In the compression-molding method, the molten resin extruded from a die head of an extruder is partly cut into a molten resin mass of a predetermined amount and is caused to fall down into a female mold for compression molding. Next, a male mold is pushed onto the molten resin mass in the female mold from the upper side thereof to effect the compression molding to obtain a desired formed article. To produce a bottle, first, a preform is produced by the compression molding and is subjected to the blow forming (see JP-A-2000-280248).
The present applicant has previously proposed a technology according to which a predetermined amount of a molten resin extruded from a die head of an extruder is cut into a molten resin mass, and a cylindrical transfer guide is used as means for transferring the molten resin mass into the female mold for compression molding. This technology enables the molten resin mass to fall down into the cavity of the female mold for compression molding without being even locally damaged (see JP-A-2005-343110).
According to the conventional apparatus for feeding the molten resin mass, however, the molten resin mass partly adheres onto the inner peripheral surface of the cylindrical transfer guide causing dispersion in the timing of falling into the female mold for compression molding, and improvement is urged from the standpoint of managing the production.
It is therefore an object of the present invention to provide a method of feeding a molten resin mass, which is capable of cutting a predetermined amount of a molten resin extruded from a die head of an extruder into a molten resin mass and of reliably causing the molten resin mass to fall down into a female mold for compression molding from a cylindrical transfer guide that transfers the molten resin mass up to the female mold for compression molding without delay in the timing, and an apparatus therefor.
In order to achieve the above object, an apparatus for feeding a molten resin mass of the invention has a cylindrical transfer guide which transfers a molten resin mass obtained by cutting a predetermined amount of a molten resin extruded from a die head of an extruder to a female mold for compression molding, wherein the transfer guide is provided with vibration-generating means for imparting vibration to the transfer guide.
The vibration-generating means includes a fixed frame, a moving member contained in the fixed frame and is capable of being finely moved, a valve member attached to the moving member and forms an air chamber relative to the fixed frame, and a push spring for pushing the valve member onto the fixed frame.
The vibration-generating means includes an air chamber having an air feed port and an air release port, and a floatable vibrator contained in the air chamber.
The vibrator may be a cylinder or a spherical body. Further, the vibrator may be constituted by a ring or may be designed in any other suitable shape.
Further, the vibrator may be directly rotated by using a drive motor.
According to another embodiment of the invention, the vibration-generating means includes an electromagnet mounted on the fixed frame, a magnetic member provided near the magnetic pole surface of the electromagnet and fixed on the side of the moving member, and a push spring for urging the moving member in a direction in which it separates away from the magnetic pole surface.
The vibration-generating means can be constituted by piezoelectric elements provided on the side of the fixed frame and on the side of the moving member facing each other.
The invention is further concerned with a compression-molding method by overlapping a cylindrical transfer guide on a female mold for compression molding, and causing a molten resin mass in the transfer guide to fall down into the female mold, wherein the pressure in the cylindrical transfer guide is set to be higher than the pressure in the female mold for compression molding.
According to an embodiment for putting the compression-molding method into practice, the pressure is reduced in the female mold for compression molding. According to another method, the pressure is elevated in a container chamber of the transfer guide. According to a further method, the pressure is elevated in the container chamber of the transfer guide and the pressure is reduced in the female mold.
Further, a compression-molding apparatus according to the present invention comprises a female mold for compression-molding a molten resin mass, a cylindrical transfer guide which can be overlapped on the female mold and is capable of containing the molten resin mass extruded from a die head of an extruder, and a pressure differential-imparting unit which sets the pressure in a container chamber of the transfer guide to be higher than the pressure in the cavity of the female mold in the compression-molding metal mold.
The invention is further concerned with a method of feeding a molten resin mass by overlapping a cylindrical transfer guide on a female mold for compression molding, and causing a molten resin mass in the transfer guide to fall down into the female mold, wherein the molten resin mass is caused to fall down by blowing a high-pressure air into a container chamber of the transfer guide from a nozzle head attached to an upper part of the transfer guide.
The high-pressure gas is desirably a compressed inert gas such as a nitrogen gas. The compressed air, too, can be used.
Further, an apparatus for feeding a molten resin mass according to the present invention comprises a female mold for compression-molding a molten resin mass, a cylindrical transfer guide which can be overlapped on the female mold and is capable of containing the molten resin mass extruded from a die head of an extruder, and a nozzle head attached to the vertex of the transfer guide and having a nozzle formed therein, wherein the nozzle head has an injection port opened in an upper region of the container chamber of the transfer guide.
The injection port in the nozzle head may comprise one or two or more circular holes, may comprise an annular groove, or may assume any other shape.
The nozzle head in the device for feeding the molten resin mass according to the invention includes a fixed housing attached to an upper part of the transfer guide, and a rotary head supported in the fixed housing so as to rotate and having a nozzle forming injection ports opened in the container chamber of the transfer guide. Here, the axis of the nozzle intersects the axis of rotation of the rotary head at a predetermined angle.
An apparatus for feeding a molten resin mass according to a further embodiment of the invention comprises:
The female mold for forming is placed on a slide plate that slides on a guide rail laid along the radial line of the turntable.
The molten resin mass transfer guide comprises a fixed blade of nearly a semicircular shape and a moving blade that can be opened and closed being coupled to the fixed blade by a hinge.
The molten resin transfer guide is placed just over the female mold for molding but just under the die head.
A guide throat is arranged between the transfer guide and the female mold for molding.
According to the method and apparatus for feeding the molten resin mass of the present invention, the molten resin mass does not adhere to the inner peripheral surface of the container chamber of the transfer guide, the molten resin mass can be fallen down into the female mold for compression forming in a short period of time and smoothly, and the production can be easily managed maintaining stability without dispersion in the falling time.
In an embodiment of controlling the temperature of the high-pressure gas to assume a predetermined temperature, it is allowed to relax the distortion at the time of cutting and molding and to improve the appearance of the molten resin mass. Further, when the high-pressure gas is cooled, stickiness of the molten resin mass can be lowered and handling property can be improved at the time of conveyance.
An embodiment of the apparatus for feeding a molten resin mass according to the invention will now be described with reference to the drawings.
Reference numeral 3 denotes lower female molds in the rotary compression-molding metal mold. Many female molds 3, 3, - - - , 3 for compression molding are arranged along the circumference on a turntable 4 maintaining an equal distance.
Between the extruder 1 and the turntable 4, there is provided a rotary cutter device 5 for cutting a predetermined amount of the molten resin extruded from the die head 2 of the extruder 1 into a molten resin mass, and for falling the molten resin mass down into the female mold 3 for compression molding. The cutter device 5 has a disk-like hub 6, and arms 7, 7, - - - , 7 are radially extending from the hub 6 maintaining an equal distance in the circumferential direction. A transfer guide 8 which constitutes a major portion of the invention is attached to an end of each arm 7. In
Referring to
The vibration-generating means 16 can be realized in a variety of embodiments which will now be described.
In this embodiment, the moving member 21 moves up and down relative to the fixed frame 20 along the guide shafts 23 and 24, and an air chamber 30 is formed in the moving member 21, the air chamber 30 being communicated with an air feed port 31 and an air release port 32. Further, a weight 33 which is a vibrator is incorporated in the air chamber 30. The weight 33 is a cylindrical member but may assume any other suitable form such as a spherical body or a ring.
In this embodiment, the compressed air is introduced into the air chamber 30 from the air feed port 31 to act upon the weight 33 so that the weight 33 rotates in a manner that the center of gravity and the center of rotation of the weight varies, and is released from the air release port 32. During this moment, the weight 33 gives impact to the movable transfer guide 21 to vibrate it. As a result, vibration is imparted to the transfer guide 8.
In an embodiment shown in
In this embodiment, the compressed air is fed from the air feed port 31 and is released from the air release port 32. During this moment, the compressed air acts on the ring 34 to rotate the ring 34. The ring 34 that rotates produces a vibratory force to impart vibration to the transfer guide 8.
In the above embodiment, the weight 33 rotates in the air chamber 30 due to the action of the air pressure of the compressed air. The weight 33, however, can be directly driven and rotated by a drive motor.
According to this embodiment, vibration occurs if an electric current is supplied to the piezoelectric elements 41 and 43; i.e., vibration is imparted to the moving member 21 via the members 40 and 42 and, as a result, the transfer guide 8 is vibrated.
According to the present invention constituted as described above, vibration is imparted to the transfer guide 8 from the vibration-generating means, a predetermined amount of the molten resin extruded from the die head 2 is cut into a molten resin mass and is caused to fall down into the female mold for compression forming at a stable timing without adhering to the inner peripheral surfaces of the container chamber 12 of the transfer guide 8.
Next, described below with reference to
According to this embodiment, an opening/closing lid 43 is attached to the top surface of the fixed transfer guide 9, and a container chamber 12 which is closed at its upper end and is opened as its lower side is formed in the transfer guide 8 in a manner to control the pressure in the container chamber 12.
Further, a number of fine air holes 45, 45, - - - , 45 are perforated in the fixed transfer guide 9 and in the moving holder 11, the air holes 45, 45, - - - , 45 being connected to a source of the compressed air that is not shown, and the compressed air is injected into the container chamber 12.
Next, the fundamental embodiment of the method of compression molding according to the invention will be described with reference to
When the moving holder 11 is closed to the fixed transfer guide 9 that constitutes the transfer guide 8, the invention so works that the pressure is P1 in the container chamber 12 formed between the above two. When the pressure in the female mold 3 for compression molding is set to be P2, the invention so works that the inner pressure P1 becomes greater than the inner pressure P2, i.e., so as to satisfy the condition P1>P2.
By using the pressure-imparting unit as described above, a pressure differential is produced between the upper side and the lower side of the molten resin mass 13. Therefore, the molten resin mass 13 falling into the container chamber 12 of the transfer guide 8 is allowed to fall down reliably into the female mold 3 for compression molding within short periods of time without dispersion in the timing.
According to the embodiment shown in
According to the present invention shown in
In order to blow the high-pressure gas into the container chamber 12 of the transfer guide 8, a nozzle 56 is formed in the gas nozzle head 55 as will be obvious from
The air feed port 58 is connected to a source of the compressed air that is not shown.
According to an embodiment shown in
An embodiment shown in
Further, an embodiment shown in
According to the above-mentioned embodiments, a high-pressure gas is injected through the injection port 57 into the container chamber 12 of the transfer guide 8, and acts onto the molten resin mass 13 so as to positively push the molten resin mass 13 down to reliably fall into the female mold.
In all of these embodiments, the high-pressure gas is injected straight into the container chamber 12 from the injection port 57 in the gas nozzle head 55. Here, it is also possible to remove irregularity in the high-pressure gas stream in the container chamber 12 by imparting a swirling motion to the high-pressure gas injected into the container chamber 12.
Next, described below with reference to
In
Further, the nozzle member 65 is attached to the retainer member 64 by a screw. An air hole 68 may be perforated in the center thereof. As is obvious from
As closely illustrated in
According to the present invention constituted as described above, the high-pressure gas fed into the container chamber 12 of the transfer guide 8 from the nozzles of the gas nozzle head 61 acts onto the upper surface of the molten resin mass 13 so as to reliably fall down into the female mold for forming.
The above embodiment has dealt with a case where the invention was applied to the cutter device 5 of the rotary type. Not being limited thereto only, however, the invention can be further applied to a cutter device of the reciprocal type as shown in
In
Unlike that of the embodiment shown in
A transfer guide 79 is provided on the guide throat 78. As will be obvious from
The fixed blade 81 and the moving blade 82 have their upper ends that are constituted as portions of cones and have their inner peripheral edges formed as blade tips 80a and 82a.
In
Number | Date | Country | Kind |
---|---|---|---|
2006-040250 | Feb 2006 | JP | national |
2006-097509 | Mar 2006 | JP | national |
2006-097510 | Mar 2006 | JP | national |
2006-125437 | Apr 2006 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2007/053334 | 2/16/2007 | WO | 00 | 8/7/2008 |