JP5086847B2 - Manufacturing method of resin tubular parts - Google Patents

Description

  The present invention relates to a method of manufacturing a cylindrical part made of a thermoplastic resin and having openings at both ends using an injection blow molding method.

As a method for producing stretch blow containers such as PET bottles, a direct blow is obtained in which a bottomed cylindrical preform is formed from a cylindrical parison formed by extrusion molding, and the preform is stretch blow molded to obtain a final product. A molding method and an injection blow molding method using a bottomed cylindrical preform formed by injection molding are widely known. For example, Patent Documents 1, 2, and 3 disclose a method for producing a plastic bottle by a direct blow molding method.
JP 2007-296650 A JP 2007-21916 A JP 2000-128195 A

  In the blow molding method, stretch molding is performed by blowing air into a bottomed cylindrical preform. Therefore, the present situation is that the blow molding method is not used for the production of a cylindrical part made of an elongated resin having both ends open, such as a liquid supply tube. For this reason, it is possible to measure a cylindrical part such as a resin tube having a thin wall and high barrier properties and transparency, for example, a flexible tube having a diameter of about 10 to 20 mm and a length of 200 to 300 mm. It was difficult to manufacture well.

  In view of this point, an object of the present invention is to propose a method for manufacturing a cylindrical product made of resin having both ends opened by using an injection blow molding method that provides relatively good dimensional accuracy. It is in.

In order to solve the above-mentioned problem, a method for manufacturing a cylindrical part made of resin according to the present invention is as follows.
A preform heating step of heating a cylindrical preform (11) having both ends opened from a thermoplastic resin to an extendable temperature; and
Before or after the preform heating step, one first end (12) and the other second end (13) of the tubular preform (11) are respectively connected to the first preform (11). Grip is grasped by the gripping tool (22) and the second gripping tool (23), and the first opening (2a) on the first end (12) side is brought into an airtight state by the first gripping tool (22) or the sealing tool. A preform gripping / blocking process to be sealed,
While the first air (35A) is blown into the cylindrical preform (11) from the second opening (3a) on the second end (13) side, the first gripping tool (22) and the first 2 By moving the gripping tool (23) in a direction relatively away along the axial direction (11a) of the cylindrical preform (11), the cylindrical preform (11) is moved in the axial direction (11a). A stretching step of molding the intermediate molded product (1A) stretched into
In the stretch blow mold (30), the intermediate molded product (1A) is sealed so that one first opening (2a) is in an airtight state, and the intermediate molded product ( The intermediate molded product (1A) is stretched by blowing the second air (35B) having a pressure higher than that of the first air into the interior of 1A), and the outer peripheral surface thereof is stretched by the stretch blow molding die (36, 37). Stretch blow molding step to obtain a cylindrical part (1) having a predetermined length and shape with both ends opened by pressing on the molding surface and shaping the outer peripheral surface;
The first end (12) and the second end (13) of the tubular preform (11) remain unstretched, and the first end (2) and the second end of the tubular part. (3) as it is,
The stretching step is performed in the stretch blow molding die (30) in a mold open state,
In at least one of the stretching step and the stretch blow molding step, the cylindrical preform (11) or the intermediate molded product (1A) from the second opening (3a) of the second end (13). The first gripping tool (22) is pushed out in the axial direction by inserting a stretching rod into the interior of the casing .

  The cylindrical part obtained by the method of the present invention has a shape in which both ends are not stretched and remain in the state of the cylindrical preform. In the present invention, paying attention to both end portions of such a cylindrical part, both end portions of the cylindrical preform are gripped by the first and second gripping tools, for example, one opening is closed by the first gripping tool, The cylindrical preform is stretched in a state. Next, the intermediate product obtained by stretching is stretch blow molded in a stretch blow molding die to obtain a cylindrical part as a final product. When the cylindrical preform is heated with both ends of the cylindrical preform held by the first and second holding tools, the cylindrical preform is covered with the first and second holding tools. Can be heated so that both ends are not heated. Further, when the first opening is sealed with the first gripping tool, a separate member for sealing the first opening is not necessary.

  In the method of the present invention, one end of both ends of the cylindrical preform is sealed, and the cylindrical preform is stretched in this state, and then stretch blow molding is performed in a stretch blow molding die. Accordingly, it is possible to produce an elongated cylindrical product by stretching and blowing a cylindrical preform having both ends opened.

Next, the manufacturing method of the cylindrical part made of resin of the present invention is as follows.
A preform heating step of heating a cylindrical preform (11) having both ends opened from a thermoplastic resin to an extendable temperature; and
Before or after the preform heating step, one first end (12) and the other second end (13) of the tubular preform (11) are respectively connected to the first preform (11). Grip is grasped by the gripping tool (22) and the second gripping tool (23), and the first opening (2a) on the first end (12) side is brought into an airtight state by the first gripping tool (22) or the sealing tool. A preform gripping / blocking process to be sealed,
While the first air (35A) is blown into the cylindrical preform (11) from the second opening (3a) on the second end (13) side, the first gripping tool (22) and the first 2 By moving the gripping tool (23) in a direction relatively away along the axial direction (11a) of the cylindrical preform (11), the cylindrical preform (11) is moved in the axial direction (11a). A stretching step of molding the intermediate molded product (1A) stretched into
In the stretch blow mold (30), the intermediate molded product (1A) is sealed so that one first opening (2a) is in an airtight state, and the intermediate molded product ( The intermediate molded product (1A) is stretched by blowing the second air (35B) having a pressure higher than that of the first air into the interior of 1A), and the outer peripheral surface thereof is stretched by the stretch blow molding die (36, 37). Stretch blow molding step to obtain a cylindrical part (1) having a predetermined length and shape with both ends opened by pressing on the molding surface and shaping the outer peripheral surface;
The first end (12) and the second end (13) of the tubular preform (11) remain unstretched, and the first end (2) and the second end of the tubular part. (3) as it is,
In the preform heating step, the tubular preform is configured so that the first gripping tool (22A) and the second gripping tool (23A) can be relatively moved only in the direction away from the axial direction (11a). (11) It connects with the rod (41) arrange | positioned in (11), The said cylindrical preform (11) is heated in this state, It is characterized by the above-mentioned.

If the cylindrical preform is inclined or contracted by the weight of the first gripping tool when the preform is heated, the height of the first gripping tool varies. For example, when the first gripping tool is gripped and pulled in the axial direction in the stretching process, the position of the first gripping tool may vary and the first gripping tool may not be gripped. If the first gripping tool and the second gripping tool are connected by a rod so that the first gripping tool and the second gripping tool can be moved only in the direction away from the axial direction, such an adverse effect can be avoided.

  According to the present invention, a cylindrical part having both ends opened can be manufactured by injection blow molding. In particular, it is suitable for manufacturing a tubular part having a longer axial length than the outer diameter.

  Embodiments of a method for manufacturing a cylindrical part to which the present invention is applied will be described below with reference to the drawings.

  Fig.1 (a) is explanatory drawing which shows an example of the liquid supply tube manufactured by the manufacturing method of this invention, and has shown one side by the cross section. FIG.1 (b) is explanatory drawing which shows the cylindrical preform used for manufacture of the said liquid supply tube, and similarly shows one side by the cross section. The liquid supply tube 1 (cylindrical part) which is a final finished product is an elongated cylindrical tube made of a thermoplastic resin, and has an average outer diameter of 10 mm to 20 mm and a length of 200 mm to 300 mm, for example. is there.

  A circular opening 2a is formed in the end surface of one first end portion 2 of the liquid supply tube 1, and the outer peripheral surface portion is a groove shape in which a small diameter portion 2d is formed between upper and lower large diameter flanges 2b and 2c. It has a cross-sectional shape. The other second end 3 is also the same, and a circular opening 3a is formed on the end surface, and the outer peripheral surface portion is a groove shape in which a small diameter portion 3d between upper and lower large diameter flanges 3b and 3c is formed. It has a cross-sectional shape. Adjacent portions of the first end 2 and the second end 3 are narrow-diameter constricted portions 4 and 5, and a large-diameter tube main body portion 6 is formed between the constricted portions 4 and 5. Yes. A bellows portion 6a is formed at the central portion of the tube body portion 6 in the direction of the axis 1a.

  A cylindrical preform 11 used to manufacture the liquid supply tube 1 having this shape includes a first end portion 12 and a second end portion 13, and a cylindrical portion 16 having substantially the same outer diameter formed therebetween. It has. The first end portion 12 and the second end portion 13 are portions that become the first end portion 2 and the second end portion 3 of the liquid supply tube 1 as they are without being stretched, and have the same shape as these. Therefore, in the figure, the corresponding parts in the first end 2 and the first end 12 are shown with the same reference numerals, and the corresponding parts in the second end 3 and the second end 13 are The same reference numerals are given.

  On the other hand, the cylindrical portion 16 of the cylindrical preform 11 is subjected to biaxial stretch blow molding to become a tube main body portion 6, a bellows portion 6 a and upper and lower constricted portions 4, 5 of the liquid supply tube 1. The outer diameter of the cylindrical portion 16 of the cylindrical preform 11 is smaller than the outer diameter of the tube main body portion 6 of the liquid supply tube 1, and the length of the cylindrical preform 11 is, for example, the length of the liquid supply tube 1. Less than half. The cylindrical preform 11 is an injection molded product of a thermoplastic resin.

  Next, FIGS. 2, 3, and 4 are explanatory views showing a process of biaxially stretching blow molding the liquid supply tube 1 from the cylindrical preform 11.

  First, as shown in FIG. 2, the first end portion 12 and the second end portion 13 of the tubular preform 11 are gripped by the first gripping tool 22 and the second gripping tool 23, respectively (preform gripping / shielding step). In this state, the cylindrical portion 16 of the cylindrical preform 11 is heated to a temperature state suitable for stretching (preform heating step).

  Here, the first gripping tool 22 is composed of a pair of gripping pieces 22 a and 22 b having a shape obtained by halving the annular member. The inner peripheral surface shape of these gripping pieces 22 a and 22 b is the same as that of the first end portion 12. The shape is complementary to the shape of the outer peripheral surface. When the gripping pieces 22 a and 22 b are closed with the first end portion 12 interposed therebetween, the first gripping tool 22 is mechanically engaged with the first end portion 12. Further, the opening 2 a is closed by the end wall 22 c of the first gripping tool 22. Further, a connecting protrusion 22 d is formed on the outer end surface of the first gripping tool 22, and a connecting member (not shown) is engaged therewith to pull the first gripping tool 22 in the axial direction of the tubular preform 11. Is possible.

  The other second gripping tool 23 is also composed of a pair of gripping pieces 23 a and 23 b in the shape of half of the annular member, and the inner peripheral surface shape of these gripping pieces 23 a and 23 b is the outer peripheral surface shape of the second end portion 13. And has a complementary shape. Accordingly, when the gripping pieces 23a and 23b are closed with the second end portion 13 interposed therebetween, the second gripping piece 23 is mechanically engaged with the second end portion 13, and the second end portion 13 is cylindrical. The preform 11 can be fixed so as not to move in the axial direction. Here, an opening 23 d having a size corresponding to the opening 3 a of the second end 13 is formed in the end wall 23 c of the second gripping piece 23, and the second holding piece 23 is attached to the second end 13. In this state, the opening 3a of the cylindrical preform 11 is not blocked. The outer peripheral edge of the end wall 23c is a large-diameter flange portion 23e.

  The tubular preform 11 is heated from the outside in a state where the first end 12 is covered with the first gripping tool 22 and the second end 13 is covered with the second gripping tool 23. Therefore, only the cylindrical part 16 to which biaxial stretch blow molding is applied can be heated.

  Next, as shown in FIG. 3, the heated cylindrical preform 11 together with the first gripping tool 22 and the second gripping tool 23 gripping the upper and lower sides of the heated cylindrical preform 11 is put into a stretch blow molding mold 30 in a mold open state. set. An air blowing tube for holding the second gripping tool 23 holding the second end 13 of the cylindrical preform 11 by the base 31 of the stretch blow mold 30 and supplying blow air from the blow air supply source 32. The lower opening 3 a of the tubular preform 11 is in communication with the 33. In addition, the tension tool 34 is connected to the connection protrusion 22 d of the first gripping tool 22 that grips the first end 12 on the upper side of the tubular preform 11.

  After that, while supplying low-pressure blow air 35A from the blow air supply source 32 into the cylindrical preform 11, the upper end portion 12 of the cylindrical preform 11 is moved to a predetermined height in the axial direction by the tension tool 34. Pull up to the position. Thereby, as shown in FIG. 3, the cylindrical part 16 of the cylindrical preform 11 is stretched by being pulled in the axial direction. Since the upper opening 2a of the cylindrical preform 11 is closed by the first gripping tool 22, the internal pressure is controlled to be a predetermined value by the low-pressure blow air supplied into the cylindrical portion 16, The cylindrical portion 16 is stretched in the axial direction with its inner diameter remaining substantially constant. As a result, an intermediate molded product 1A having approximately the same length as the liquid supply tube 1 that is a finished product is obtained (stretching step). This intermediate molded product 1A includes a first end portion 12 and a second end portion 13 and an elongated body portion 6A having an elongated and substantially constant diameter formed therebetween.

  Next, as shown in FIG. 4, the left and right molds 36 and 37 of the blow mold 30 are closed. After closing the mold, high pressure blow air 35B is supplied from the blow air supply source 32 through the air blowing pipe 33 into the intermediate molded product 1A to biaxially stretch blow mold the intermediate molded product 1A (stretch blow molding process). As a result, the liquid supply tube 1 having the shape shown in FIG. The upper and lower first end portions 2 and the second end portion 3 of the liquid supply tube 1 are portions where the upper and lower first end portions 12 and the second end portion 13 of the cylindrical preform 11 remain as they are.

  In this way, the elongated liquid supply tube 1 having both ends opened can be manufactured by biaxially stretching blow-molding the cylindrical preform 11 having both ends opened by injection molding. By the biaxial stretch blow molding, the liquid supply tube 1 which is thin, excellent in barrier properties, transparency, etc., and excellent in dimensional accuracy can be obtained.

  Needless to say, the method of the present invention can be used to manufacture a cylindrical part that is open at both ends other than the liquid supply tube.

  In the above example, the tubular preform 11 is stretched by pulling up the first gripping tool 22 with the pulling tool 34. Instead, stretching may be performed using a stretching rod used in biaxial stretching blow molding. That is, a stretching rod may be inserted in the axial direction from the opening 3a of the second end portion 13 of the cylindrical preform 11, and the first gripping tool 22 may be pushed out in the axial direction by the stretching rod.

  Further, before the first and second gripping tools 22 and 23 are attached to the tubular preform 11, a heating process of the tubular preform 11 may be performed.

  On the other hand, when attaching a gripping tool before heating, the gripping tool set shown in FIG. 5 can be used. In the preform heating step, when the tubular preform 11 is heated and softened, the tubular preform 11 may be deformed by the weight of the upper first gripping tool 22 and may be inclined or contracted. As a result, there is a variation in the position of the first gripping tool 22 after heating, and there is a possibility that the connecting protrusion 22d of the second gripping tool 23 cannot be gripped by the pulling tool 34 in the stretching process.

  The gripping tool set 40 shown in FIG. 5 is for avoiding such harmful effects. The gripping tool set 40 includes a first gripping tool 22A, a second gripping tool 23A, and a connecting rod 41. Since the basic configuration of the first gripping tool 22A and the second gripping tool 23A is the same as that of the first gripping tool 22 and the second gripping tool 23, the corresponding parts are denoted by the same reference numerals and description thereof is omitted. . The connecting rod 41 includes a rod main body 41a extending through the cylindrical preform 11, a medium diameter part 41b continuous with one end of the rod main body 41a, and a large diameter part formed at the end of the medium diameter part 41b. 41c. The middle diameter portion 41 b is mounted inside the first end portion 12 of the tubular preform 11, and the large diameter portion 41 c is formed between the end wall 22 c of the first gripping tool 22 and the first end portion 12 of the tubular preform 11. The rod 41 is sandwiched so as not to move in the axial direction 11a.

  On the other hand, the tip end portion 41d of the rod main body 41a is attached to the second gripping tool 23A in a detachable state. A cylindrical portion 23f protruding into the cylindrical preform 11 is formed on the inner peripheral edge of the end wall 23c of the second gripping tool 23A, and the distal end portion 41d of the rod main body 41a is formed on the cylindrical portion 23f from above. It is inserted in a state where it can be pulled out in the axial direction 11a.

  If the cylindrical preform 11 is heated while being rotated about its axis in the state shown in FIG. 5, the heated and softened tubular preform 11 can be prevented from being deformed by the weight of the first gripping tool 22A. . Further, in the stretching step after heating, when the first gripping tool 22A is pulled up in the axial direction 11a, the tip 41d of the rod body 41a of the rod 41 comes out of the second gripping tool 23A, and the tubular preform 11 is stretched. be able to.

(A) is explanatory drawing which shows the liquid supply tube manufactured by this invention, (b) is explanatory drawing which shows the cylindrical preform manufactured by injection molding in order to use for manufacture of the said liquid supply tube. . (A) is a longitudinal sectional view showing a preform gripping / sealing process and a heating process in which both ends of a cylindrical preform are gripped by a gripping tool, (b) is a plan view thereof, and (c) is a bottom view thereof. It is. It is explanatory drawing which shows the extending | stretching process which set and extended the cylindrical preform after a heating to the extending | stretching blow molding die of a mold open state. It is explanatory drawing which shows the biaxial stretch blow molding process by a stretch blow molding die. It is explanatory drawing which shows the example of the holding tool set which can be used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid supply tube 2 1st end part 2a Opening 3 2nd end part 3a Opening 4 and 5 Constriction part 6 Tube body part 11 Cylindrical preform 12 1st end part 13 2nd end part 16 Cylindrical part 22, 22A 1st Gripping tool 22a, 22b Gripping piece 22c End wall 22d Connecting projection 23, 23A Second gripping tool 23a, 23b Gripping piece 23d Opening 23e Flange part 23f Cylindrical part 30 Stretch blow molding die 31 Base 32 Blow air supply source 33 Blow air supply source 33 Blow pipe 34 Tensioner 35A Low pressure blow air 35B High pressure blow air 36, 37 Mold 40 Holding tool set 41 Rod 41a Rod body 41b Medium diameter part 41c Large diameter part 41d Tip

Claims (2)

A preform heating step of heating a cylindrical preform (11) having both ends opened from a thermoplastic resin to an extendable temperature; and
Before or after the preform heating step, one first end (12) and the other second end (13) of the tubular preform (11) are respectively connected to the first preform (11). Grip is grasped by the gripping tool (22) and the second gripping tool (23), and the first opening (2a) on the first end (12) side is brought into an airtight state by the first gripping tool (22) or the sealing tool. A preform gripping / blocking process to be sealed,
While the first air (35A) is blown into the cylindrical preform (11) from the second opening (3a) on the second end (13) side, the first gripping tool (22) and the first 2 By moving the gripping tool (23) in a direction relatively away along the axial direction (11a) of the cylindrical preform (11), the cylindrical preform (11) is moved in the axial direction (11a). A stretching step of molding the intermediate molded product (1A) stretched into
In the stretch blow mold (30), the intermediate molded product (1A) is sealed so that one first opening (2a) is in an airtight state, and the intermediate molded product ( The intermediate molded product (1A) is stretched by blowing the second air (35B) having a pressure higher than that of the first air into the interior of 1A), and the outer peripheral surface thereof is stretched by the stretch blow molding die (36, 37). Stretch blow molding step to obtain a cylindrical part (1) having a predetermined length and shape with both ends opened by pressing on the molding surface and shaping the outer peripheral surface;
The first end (12) and the second end (13) of the tubular preform (11) remain unstretched, and the first end (2) and the second end of the tubular part. (3) as it is,
The stretching step is performed in the stretch blow molding die (30) in a mold open state,
In at least one of the stretching step and the stretch blow molding step, the cylindrical preform (11) or the intermediate molded product (1A) from the second opening (3a) of the second end (13). A method for producing a resin-made cylindrical part, comprising: inserting a stretching rod into the inside of the housing and extruding the first gripping tool (22) in the axial direction by the stretching rod . A preform heating step of heating a cylindrical preform (11) having both ends opened from a thermoplastic resin to an extendable temperature; and
Before or after the preform heating step, one first end (12) and the other second end (13) of the tubular preform (11) are respectively connected to the first preform (11). Grip is grasped by the gripping tool (22) and the second gripping tool (23), and the first opening (2a) on the first end (12) side is brought into an airtight state by the first gripping tool (22) or the sealing tool. A preform gripping / blocking process to be sealed,
While the first air (35A) is blown into the cylindrical preform (11) from the second opening (3a) on the second end (13) side, the first gripping tool (22) and the first 2 By moving the gripping tool (23) in a direction relatively away along the axial direction (11a) of the cylindrical preform (11), the cylindrical preform (11) is moved in the axial direction (11a). A stretching step of molding the intermediate molded product (1A) stretched into
In the stretch blow mold (30), the intermediate molded product (1A) is sealed so that one first opening (2a) is in an airtight state, and the intermediate molded product ( The intermediate molded product (1A) is stretched by blowing the second air (35B) having a pressure higher than that of the first air into the interior of 1A), and the outer peripheral surface thereof is stretched by the stretch blow molding die (36, 37). Stretch blow molding step to obtain a cylindrical part (1) having a predetermined length and shape with both ends opened by pressing on the molding surface and shaping the outer peripheral surface;
The first end (12) and the second end (13) of the tubular preform (11) remain unstretched, and the first end (2) and the second end of the tubular part. (3) as it is,
In the preform heating step, the cylindrical preform is configured so that the first gripping tool (22A) and the second gripping tool (23A) can be relatively moved only in the direction away from the axial direction (11a). (11) A method for producing a resin-made tubular part, characterized in that the tubular preform (11) is heated in this state by being connected by a rod (41) arranged in the interior .

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