JP3392408B2 - Method of manufacturing straight pipe with single receiving port and molding apparatus used in this method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a straight pipe with a single socket and a molding apparatus used in this manufacturing method.

[0002]

2. Description of the Related Art As a method for forming a receiving port at the end of a resin pipe material, the following method has been conventionally performed.

(1) A method of press-fitting a mold having an outer surface conforming to the inner surface shape of the receiving port (sleeve method) into a receiving port forming portion such as a resin pipe as a cylindrical molding material (2) tubular molding material A so-called petal core in which a part of the core mold (shell) is hydraulically moved so as to be expanded outward and the pipe is expanded to form a receptacle ( Hydraulic shell expansion method)

(3) As disclosed in Japanese Patent Application Laid-Open Nos. 7-1580 and 7-1582, etc., after being inserted into a core mold in a resin pipe as a cylindrical molding material,
A method using a so-called petal core in which a pipe is expanded by mechanically moving a part of the core mold (shell) to the outside and expanded to form a socket (shell expansion method by mechanical action)

(4) A method of obtaining a receptacle by forming a molded article having a shape similar to a socket without an undercut portion by injection molding and then cutting the molded article similar to the socket to form an undercut portion ( 5) A method of cutting a thick pipe or a cylindrical rod extruded into a socket shape

However, each of the above conventional methods has the following problems. In the case of the above method (1), the mold structure is simple, but a large force is required when the core mold is press-fitted or withdrawn. Moreover, when the receiving opening has a large concave and convex undercut portion such as a fitting groove of a rubber ring, there is a possibility that the core mold may not come off from the molded product after molding.

In the case of the above method (2), since the shell moves in the diameter expanding direction and comes into close contact with the inner surface of the resin pipe, a mold mark remains on the inner surface of the obtained receiving portion, resulting in poor appearance. Also, there is a risk that the rubber ring for sealing fitted inside the receptacle may be improperly mounted. In addition, due to the structure of the shell, when a holding pressure is applied after filling, it is difficult to apply a large holding pressure because the device may be broken. In the case of the above method (3), the shell diameter-expanding mechanism is complicated, and the number of parts is large, which easily causes a failure. Further, since the structure of the mold is complicated, it is unsuitable for molding a small-diameter one and the manufacturing cost of the mold becomes high.

In the case of the above methods (4) and (5), the receptacle can be molded with high accuracy, but the processing cost is high. Further, it is difficult to cut the end portion of the straight pipe, and first, a method of adhering or fusing the joint obtained by the cutting work to the end portion of the straight pipe must be taken, which increases the cost of the secondary processing.

[0009]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has a socket forming section having a simple structure of a forming apparatus and having an undercut section on at least a part of the inner surface.
An object of the present invention is to provide a method for manufacturing a straight pipe with a single- ended mouth that can form a straight pipe with a single- ended mouth with high accuracy and a high appearance, and a molding apparatus used for this manufacturing method.

[0010]

In order to achieve such an object, a single-sided receiver according to the invention as set forth in claim 1 of the present invention.
A method for manufacturing a straight pipe with a mouth (hereinafter, referred to as a “manufacturing method of the present invention”) is a mouthpiece forming part having an undercut part on an inner surface.
In the method for producing a straight pipe with a single socket including: a core mold having an outer surface shape substantially corresponding to the inner surface shape of the socket molding section, a tubular molding having an inner diameter larger than the maximum diameter section of the core mold. The core mold inserting step of relatively moving the core mold in the axial direction of the material and inserting it into the processed part , and at least the outer surface shape of the mouth molding part.
It has a substantially corresponding inner surface shape and is divided into two or more parts in the axial direction.
Before assembling the outer mold, which consists of a freely assembled split mold
The outer die mounting step of surrounding the processing portion with an outer die , the molding material heating step of heating at least the processing portion of the tubular molding material to make it into a deformable state, and the inner peripheral surface of the minimum diameter portion of the outer die.
While fixing the cylindrical molding material by clamping the outer peripheral surface of the processing part, while eccentric while keeping the central axis of the core mold parallel to the central axis of the mouth molding part to be molded, receiving while compressing the working portion by revolving around the central axis of the socket forming portion to be formed in the outer circumferential direction of the cylindrical molding material in the core mold outer surface
Molding process to mold the mouth molding part and cooling with a predetermined temperature gradient
The first stage of cooling to the crystallization start temperature at a
After the 1st step, the 2nd step of maintaining the temperature at the crystallization start temperature
And after the end of the second stage, cooling at a cooling rate with a predetermined temperature gradient
Cooling and solidifying step consisting of the third step of
The maximum distance from the center axis to the outer peripheral surface of the core mold is
Insert the core mold into the mouth molding part so that it is larger than the minimum inner diameter.
While moving it in the axial direction, place the outer mold inside the mouth molding part.
The distance from the mandrel to the minimum inner diameter of the split mold is
A mold releasing step in which a straight pipe with a single socket having a socket forming section is relatively moved in the axial direction of the core mold and then is separated after being divided into a state of being larger than the maximum outer diameter. , And are provided.

Meanwhile, the molding apparatus according to the invention of claim 2 of the present invention (hereinafter, referred to as "molding device of the present invention")
Is a core mold having an outer surface shape substantially corresponding to an inner surface shape including an undercut portion provided in a straight tube with a single- ended opening to be molded, and a maximum outer diameter smaller than the inner diameter of the tubular molding material, and a cylinder. Outside the processed part that is the receiving molding part of the molding material
It is possible to assemble it so as to surround it, and the socket molding part is
It consists of multiple split types that can be taken out,
Has an inner surface shape that approximately corresponds to the outer surface shape of the mouthpiece molding part
Fixing means for fixing the tubular molding material consisting of an outer mold ,
Receiving to be formed on the central axis of the core mold in a state of being surrounded by the outer mold
While eccentric while maintaining the parallel state with respect to the central axis of the mouth forming portion, an outer form of the inner surface direction of the processing unit by revolving around the central axis of the socket forming portion to be molded core mold with a core mold outer surface To
And a core type eccentric revolution mechanism for compression .

[0012] In the molding apparatus of the present invention, as described in claim 3.
As shown in the figure, the core type eccentric revolution mechanism is
Rolling case, advancing / retreating member, slide block, core type
And a shaft portion that rotatably supports the
Is supported by bearings and transmits the rotational driving force of the electric motor.
And is freely rotatable in the casing.
The advancing / retreating member slides inside the rotating case toward the core mold.
It is freely inserted and its rear end is a hydraulic cylinder.
Is rotatably supported at the rod end of the
The hydraulic cylinder rotates with the rotation of the base.
The core of the rotating case is formed by expanding and contracting the rod of the dar.
It is designed to move back and forth in the direction.
Inclination with respect to the slide shaft of the advancing / retreating member on the surface of the die
Angular pins are projected on the slide block.
The hook has a connecting pin on the surface on the core mold side, and
The side surface has the same cross-sectional shape and the same angle as the angular pin.
Angular holes that are inclined at
The angular pin is slidably inserted in the hole
And the connecting pin of the slide block is attached to the shaft portion.
Preferably, it is fixed.

In the molding apparatus of the present invention, as described in claim 4 , the core type eccentric revolving mechanism is provided so that the tip faces the inside of the core die from one end of the core die, and is driven to rotate by a motor. The shaft and an arm, one end of which is fixed to the drive shaft inside the core mold, rotates with the rotation of the drive shaft, an external gear provided along the inner peripheral surface of the core mold, and the other end of the arm. It has an internal gear that is freely pivoted and inscribes in the external gear, and a driving force transmission means that transmits the rotational driving force of the drive shaft to the internal gear. Is preferably detachable, and preferably has a plurality of pairs of external and internal gears of different modules.

As a material of the molding material used in the production method of the present invention, a resin having a high degree of crystallinity and a high shrinkability such as high density polyethylene is suitable, but an amorphous material such as vinyl chloride resin or polystyrene. Resins can also be used.

[0015] As the material of the core mold, but are not limited to, the portion forming the mold surface of at least the core type, high thermal conductivity aluminum, aluminum alloy, zinc alloy,
It is preferably formed of a copper alloy or the like, and of these, aluminum or aluminum alloy is more preferable from the viewpoint of weight reduction.

[0016] As the outer mold material of is not particularly limited, for example, carbon steel or stainless steel. Further, in order to improve transferability, it is preferable that the portion in contact with the resin be mirror-finished.

[0017] The core-type shape (diameter) by varying appropriately, it is possible to perform compression commensurate with the contraction amount of the molding material used.

The amount of eccentricity of the core mold is not particularly limited as the molding conditions and the amount of shrinkage differ depending on the size and shape of the molded portion of the molded product or the type of resin used, but for example, high density polyethylene is used to obtain a nominal diameter of 50. When molding the piping material with a socket of No. 1, about 0.1 to 20 mm is preferable.

In the present invention, the term "cylindrical" means not only a cylindrical shape having a perfect circular cross section, but also an oval shape or an elliptical shape, and various shapes on the surface. The convex portion may be provided so as to project.

In the manufacturing method of the present invention, the molding material heating step may be performed before or after the core die is inserted into the processing portion. The method of heating the processed portion before inserting the core mold into the processed portion is not particularly limited, but a method of immersing and heating at least the processed portion of the tubular molding material in an oil bath, a far infrared heater, a sheath heater, etc. The method of heating with a heater, the method of supplying hot air with a blower or the like to heat, and the like. The method of heating the processed part after inserting the core mold into the processed part is not particularly limited, but the method of heating with a heater provided in the core mold and the outer mold or the method of heating the processed part in the core mold and the outer mold is provided. In addition, a method of heating by supplying a heat medium such as steam or heating oil to the heat medium flow path may be used.

The easily deformable state means a state in which the processed portion is easily deformed by the eccentric revolution of the core type, and the heating temperature at this time is equal to or higher than the softening point temperature of the material forming the tubular molding material. Is preferred.

In the manufacturing method of the present invention, the contact between the core mold and the tubular molding material during compression in the molding step is preferably point contact because it promotes stretching and rolling.

In addition, in the manufacturing method of the present invention, it is necessary to provide a cooling step for cooling the mouthpiece molding portion to a temperature not higher than the temperature at which the resin can be easily deformed, before carrying out the mold releasing step . The cooling step is necessary to configure the a first step of cooling rate, a second step of cooling rate from the cooling rate of the first stage, a third stage of the cooling rate from the cooling rate of the second stage But
If the material forming the tubular molding material is a crystalline resin such as polyethylene, the cooling step is composed of three stages, the cooling rate is high in the first stage and once in the second stage.
It is necessary to keep the temperature constant, maintain the temperature for a while, and increase the cooling rate again in the third stage, and especially the temperature in the second stage needs to be near the crystallization start temperature .

In the cooling step, the cooling rate pattern used for cooling depends on the crystalline resin used and the degree of crystallinity aimed at. Regarding the crystalline resin used, it is necessary to grasp the relationship between the cooling rate and the crystallinity in advance. In order to understand the relationship between the cooling rate and the crystallinity, the crystallinity of the resin sample solidified at various cooling rates can be calculated by
Measure with SC etc. to understand the relationship between the cooling rate and the crystallinity. Further, if a DSC or PvT measuring device that can change the cooling rate is used, it is possible to grasp the crystallization start temperature and the crystallization temperature range that change depending on the cooling rate. Particularly in the case of DSC capable of setting a wide range of cooling rates, the resin sample is cooled in a cooling pattern to be actually molded, and the crystallinity is measured with the sample to which the temperature history is given, whereby the crystal in various cooling patterns is measured. You can grasp the degree of change.

[0025] Here, the crystallization starting temperature or the crystallization temperature range, judging from the results obtained by DSC or PvT measured in the cooling step. That is, in the case of using DSC, the temperature range in which the curve greatly deviates from the baseline is the crystallization temperature range from the temperature-calorie curve,
The maximum value among them is the crystallization start temperature. Also, PvT
In the case of measurement, in the temperature-specific volume curve, the temperature range in which the rate of change of the specific volume is the largest is the crystallization temperature range, and the maximum value thereof is the crystallization start temperature.

In the manufacturing method of the present invention, the means for changing the cooling rate is not particularly limited.
The following four methods can be adopted. (1) A method of changing the flow rate of the refrigerant. (2) Switching refrigerants having different temperatures. (3) The passage position of the refrigerant is switched. (4) A method of using cooling by a refrigerant and heating by a heater in combination.

[0027] As changes monkey method the flow rate of refrigerant in the above (1) can be varied the cooling rate by changing the flow rate of the refrigerant flowing through the cooling tube in the mold. That is, as the flow rate of the refrigerant increases, the heat transfer efficiency increases and the cooling rate increases. The flow rate is controlled in a wide range of, for example, 0 to 20 liters / minute by using a refrigerant pumping device. During the cooling process, the cooling rate can be changed at a preset timing by controlling the opening amount of the flow rate control valve provided in the cooling pipe manually or according to a signal from the control device.

In the method (2) of switching refrigerants having different temperatures, a plurality of mold temperature controllers (temperature controllers) are used and a plurality of refrigerants having different temperatures are used. The cooling rate is changed by utilizing the fact that the cooling rate changes depending on the temperature difference between the mold and the coolant. In this case, the larger the temperature difference, the faster the cooling rate. During the cooling process, manually or according to a signal from the control device, appropriately switch the electromagnetic valve provided in the pipe from the mold temperature control device, supply to the refrigerant flow pipe of the mold, by switching these refrigerants in advance, The cooling rate can be changed at the set timing.

In some cases, the temperature can be set in a wider range (for example, 5 to 180 ° C.) by changing the kind of the refrigerant, that is, the chiller, water, oil and the like. In this method, it is possible to maintain the temperature of the peripheral wall surface of the cylindrical cavity at a constant temperature (cooling rate = 0), and further to reheat within the temperature range of the refrigerant if necessary. A plurality of mold temperature control devices for different types of refrigerant are used, the solenoid valves provided in the pipes from each mold temperature control device are switched as appropriate to supply to the mold refrigerant flow pipe, and these different The temperature of the mold can be set by switching the type of refrigerant.

In the method (3) for switching the passage position of the refrigerant, the cavity and the refrigerant are selectively flowed through the cooling pipes arranged in the mold so that the distances to the cylindrical cavity portion are different. The cooling rate can be changed by utilizing the fact that the distance between and affects the heat transfer efficiency. In this case, the shorter the distance between the cavity and the cooling pipe, the faster the cooling rate. During the cooling process, the cooling rate can be changed at a preset timing by switching the flow path through which the refrigerant flows, either manually or according to a signal from the control device.

In the method (4) in which the cooling by the refrigerant and the heating by the heater are used in combination, a cooling pipe for passing the refrigerant through the mold and a heater are provided, and the cooling rate by the refrigerant is adjusted by the heater. , The cooling rate can be changed.

[0032] Alternatively, using a plurality of mold temperature regulating apparatus, the coolant is supplied to the refrigerant tubes of the mold by one mold temperature regulating apparatus, the mold heating medium by the other mold temperature control device You may make it supply to a heating medium flow pipe.
During the cooling process, manually or according to the signal from the controller,
By turning on / off the heater, the cooling rate can be changed at a preset timing.

[0033] may be used alone above 4 methods, respectively, it may be by a combination of these methods as appropriate,
According to the combined method, the control range or the control pattern can be further expanded. The heating heater is not particularly limited, but for example, a sheath heater, high frequency heating, heating means such as near infrared rays or far infrared rays can be used.

Further , the cooling rate may be judged and controlled by the resin temperature of the processed portion in contact with the molding surface of the core mold and the outer mold or the molding surface, or the elapsed time during the molding cycle.

As the simplest control means, the set values of the above-mentioned four cooling rate varying methods are checked in advance for the required cooling rate, and the elapsed time during the molding cycle (for example, from the start of resin filling and the start of cooling) Elapsed time), the set value may be switched manually or by timer control. In this method, if the set value is derived in advance, it is not always necessary to measure the peripheral wall surface temperature of the cylindrical cavity or the resin temperature in actual molding. However, it should be noted that there is a possibility that the actual cooling pattern and the target pattern may be slightly deviated from each other due to disturbances such as changes in atmospheric temperature and molding conditions.

In order to control the cooling speed more accurately, it is necessary to install a sensor for measuring the temperature of the molding surface of the core mold and the outer mold or the resin in contact with the molding surface as needed to control the cooling speed. is there. The measurement data from the sensor is sent to the control unit, the cooling rate is calculated every moment from the temperature gradient with respect to the measurement interval, and the cooling rate is controlled so as to reach the preset cooling rate.

In the second stage, when a constant temperature is maintained, it is preferable to control so that the set temperature is maintained for the time set as the cooling pattern.

The core shape, the maximum outer diameter need only be designed to be smaller than the cylindrical molding material inside diameter, but making the size of the portion contacting the like undercut portion and parallel portion is expected to advance thermal shrinkage It is preferable to design with a flat dimension. The amount of eccentricity of the core die is designed to be an amount necessary for the locus to move in a dimension (product dimension) along the inner surface shape of the socket molding portion when the core die makes an eccentric revolution movement.

In the core mold, the entire peripheral surface may be formed integrally , but the peripheral wall of the core mold is rotatable about the central axis of the core mold so that the core mold revolves and rolls along the inner surface of the machined portion. It is preferable that the structure is movable. If the undercut amount (groove depth, etc.) is large, or
In the case where the uneven shape of the inner surface of the mouthpiece part changes suddenly
Are, for example, the it is preferable to allow roll individually to the divided independent structures otherwise undercut portion. That is, by dividing, each part (undercut part and other parts) rolls individually according to the revolution speed during eccentric revolution, so the friction resistance between the resin and the core mold surface is small. Twisting on the machined surface is less likely to occur.

The outer die may be formed with a vacuum suction hole or a vacuum suction groove on its molding surface to the extent that it does not affect the external appearance of the receptacle molding portion in order to improve the shaping accuracy and dimensions. Absent. In addition, the molding apparatus of the present invention is not limited to a mold alone, but can be incorporated into an extrusion molding line for molding a cylindrical molding material so that pipe molding, heating of a processing portion, and the above-described socket processing mold are performed on the line. It can be used in a method of integrally processing by installing it in the.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
A detailed description will be given with reference to the drawings. FIG. 1 shows one embodiment of a method and apparatus for manufacturing a tubular molded product according to the present invention.

As shown in FIG . 1, this molding apparatus 1a is
A ring shape including a core mold 2a, an outer mold 3, and a core type eccentric revolution mechanism 4, into which a sealing rubber ring (not shown) as shown in FIG. 2 (a) is fitted as a cylindrical molded product. It is possible to mold the straight pipe 5 with a single socket having the socket 51 provided on the inner surface as the recessed groove 52 for a rubber ring as an undercut part as a socket molding part. That is, as shown in FIGS. 1 and 3, the core mold 2a has a tubular shape in which the outer surface 21 has a vertical cross-section uneven shape that is substantially the same as the vertical cross-section uneven shape of the inner surface of the receiving port 51. As described above, the shaft main body 452 of the core type eccentric mechanism 4 is inserted from one end, and the shaft main body 452 is rotatable about the central axis of the core mold 2a via the bearing 6 fitted onto the shaft main body 452. Also, the core mold 2a
Has a maximum diameter slightly smaller than the inner diameter of the pre-extruded resin pipe 5a which is a tubular molding material.

The outer die 3 is provided with two split dies 31, 31 and a support plate 32 which are divided along the axis thereof, and has an inner surface shape along the outer peripheral surface of the mouth 51 which is a mouth forming part. In addition, its minimum diameter is substantially the same as the outer diameter of the resin pipe 5a. Further, the support plate 32 supports the split molds 31 and 31 so as to be movable in and out of contact with each other, and has a through hole 33 for a shaft main body 452, which will be described later, formed in the center thereof.
Further, the outer mold 3 is provided with a heater 34 and a cooling pipe 35 through which the refrigerant passes along the molding surface.

As shown in FIG . 1, the core type eccentric revolution mechanism 4
Includes a casing 41, a rotating case 42, a forward / backward member (push / pull angular contact) 43, a slide block (eccentric angular contact) 44, and a shaft portion 45 rotatably supporting the core mold 2a. The rotating case 42 is supported by a bearing 46 and is rotatable in the casing 41, and a sprocket 47 is fitted onto the rotating case 42.

The rotary case 42 is rotated in the casing 41 by transmitting the rotational driving force of the electric motor 48 through the gear 481, the chain 49 and the sprocket 47 provided on the rotary shaft of the electric motor 48. There is.

The advancing / retreating member 43 has a substantially oval cross section, is slidably inserted in the rotating case 42 in the direction of the core mold, and its rear end rotates to the rod tip of a hydraulic cylinder (not shown). It is freely supported, and rotates with the rotation of the rotary case 42, and also moves back and forth in the core case 2a direction inside the rotary case 42 due to expansion and contraction of the rod of the hydraulic cylinder.

Further , the advancing / retreating member 43 is provided with an angular pin 431, which has a rectangular cross section and is inclined with respect to the slide shaft of the advancing / retreating member 43, on the surface on the core die 2a side.

Meanwhile, the slide block 44, the core mold 2
A connecting pin 44 that is connected to a shaft portion 45 described later on the a-side surface
1, and the angular pin 431 on the surface of the advancing / retreating member 43 side.
Angular hole 44 with the same cross-sectional shape and inclination at the same angle
2 is bored, and the angular pin 431 is slidably inserted into the angular hole 442.

[0049] That is, the sliding block 44, by advancing and retracting member 43 is advanced retracted core mold 2a direction, the angular pin 431 forward and backward in the angular hole 442. Moreover, since the angular hole 442 and the angular pin 431 are provided so as to be inclined with respect to the advancing / retreating direction of the advancing / retreating member 43, the central axis of the angular pin 431 is moved by the advancing / retreating of the angular pin 431 into the angular die 2a.
It slides in the rotating case 42 in a direction orthogonal to the central axis of the. When the advancing / retreating member 43 rotates with the rotation of the rotating case 42, the angular pin 43 is rotated.
The rotational force is also transmitted to the slide block 44 via 1, and the slide block 44 also rotates together with the advancing / retreating member 43.

The shaft portion 45 includes a base portion 451 and a shaft portion main body 4
52 and the base pin 451 has its central axis aligned with the central axis of the slide block 44.
It is fixed through 41. The shaft body 452 is inserted into the core mold 2a while facing the inside of the outer mold 3 through the insertion hole 33 provided in the support plate 32, and the core mold 2a is detachably supported via the bearing 6. In addition, it is rotatable around the shaft body 452.

Further , in the shaft portion main body 452, the core mold 2a
A heater 453 for heating the heater and a cooling water cooling pipe 454 for cooling the core die 2a are provided.

The advancing / retreating member 43 and the slide block 4
The material of No. 4 is not particularly limited, but it is preferable that at least the portion forming the contact portion of the advancing / retreating member 43 and the slide block 44 is made of a material having impact resistance, dust resistance, etc. From maraging steel, chrome-molybdenum steel (SMC steel) and tool steel (SK
D steel) is more preferable. Further, in consideration of abrasion resistance and low friction, it is more preferable to perform surface heat treatment such as vacuum quenching and tuftride.

Next, explaining the forming method of the present invention using the molding apparatus A by FIGS. 4 and 5 in the order of steps.

As shown in FIG . 4 (a), the outer mold 3 has two
The two split dies 31, 31 are separated from each other, and the core die 2a is kept in a state where its central axis coincides with the central axis of the insertion hole 33 of the support plate 32. Heaters 34,453
The molding surfaces of the outer mold 3 and the core mold 2a are heated up to the easy base deformation temperature of the resin pipe 5a.

The processed portion 55, which is one end of the resin pipe 5a heated above the easily deformable temperature in the oil bath, is fitted onto the core mold 2a. As shown in FIG. 4 (b), the two split dies 31, 31 are closed and the outer die 3 is used to form the processing portion 55.
And the outer peripheral surface of the resin pipe 5a is clamped by the smallest diameter portion of the outer mold 3.

As shown in FIG . 4C, while rotating the rotating case 42, the advancing / retreating member 43 is gradually moved to the core mold 2.
The resin pipe 5a is compressed in the mold surface direction of the outer mold 3 while advancing to the a side to eccentric the core mold 2a. Figure 5
As shown in (a), while rotating the rotating case 42, the eccentric amount of the core mold 2a is further increased and the core mold 2a is uniformly compressed with the outer mold 3 over the entire circumference to form the receptacle 51.

After cooling water is passed through the cooling pipes 35 and 454 to cool the outer mold 3 and the core mold 2a to cool and solidify the resin, the core mold 2a is returned to the neutral position as shown in FIG. 5 (b). , The outer mold 3 as shown in FIG.
The two split molds 31 and 31 are separated so that the minimum diameter portion thereof is located at a position apart from the maximum outer diameter portion of the receiving opening 51 from the central axis of the receiving opening 51.

As shown in FIG . 5 (c), the straight pipe 5 with a single receiving port, in which the receiving port 51 is formed, is extracted in the axial direction of the core mold 2a and separated. However, it is not necessary to return the core mold 2a to the neutral position as long as it does not hinder the mold release. In addition,
The steps of and may be reversed in order.

[0059] Method This molding is adapted to the above, it has the following excellent effects. (1) Since the maximum diameter of the core mold 2a is the same as or slightly smaller than the inner diameter of the resin pipe 5a, a large force is not required when inserting the core mold 2a into the processing portion 55 and when removing it from the receiving opening 51. is there. Moreover, the inner surface of the processed portion 55 is not damaged when the core die 2a is inserted into the processed portion 55.

[0060] (2) Since the core mold 2a does not become complex as a petal core, it can be reduced in manufacturing cost. (3) Since the processed portion 55 is compressed from the inner surface side by the core mold 2a, the inner surface accuracy is better than that of the method using the petal core.

[0061] (4) the mold mark does not occur, such as the method using the petals core. By adjusting the amount of eccentricity of the core mold 2a, the degree of unevenness of the undercut portion can be adjusted. (5) Even a complicated undercut shape or a large uneven cross-sectional shape can be easily formed.

[0062] (6) be incorporated in extrusion line can receptacle integrally processed into one or both ends. (7) Since the core mold 2a can have a simple structure, it is possible to mold a molded product having a small diameter.

[0063] (8) the outer contour or inner surface shape of the core mold 2a and outer mold 3 only be exchanged with the socket 51 can be easily changed. That is, molded products of various shapes can be manufactured at low cost. (9) Since the core die 2a is made to roll along the inner surface of the processed portion 55 during the forming step, there is little friction between the core die 2a and the inner surface of the processed portion 55, and twists, wrinkles, etc. on the formed surface. Does not occur.

[0064] (10) Since so as to clamp the outer peripheral surface of the plastic pipe 5a at the minimum diameter portion of the outer mold 3 during the molding process, is not the resin Paifu 5a is or move displacement when eccentricity revolution of the core type 2a . That is, the processed portion 55 can be accurately formed into a predetermined shape of the receiving port 51.

[0065] On the other hand, the molding device 1a, since so above, has the following excellent effects.

[0066] (1) core mold 2a revolves while maintaining the eccentricity state, moreover, since the circumferential surface of the core mold 2a rolls smoothly along the working portion 55 the inner surface, the resin of the processing member 55 from the inside Compress uniformly vertically toward the molding surface of the outer mold 3,
Since the shrinkage force of the resin can be dispersed evenly, the shape can be corrected and the density can be increased. That has a uniform density, warp or deformation, residual strain and the like less, with a size of no shrinkage unevenness precision, with a (excellent to the mold transferability) socket molded part excellent appearance pieces A straight pipe with a socket can be obtained. Further, since the core mold 2a rolls smoothly, shear stress is reduced.

[0067] (2) a reciprocating member 43 since to allow eccentric core type 2a by simply advancing and retracting the core mold 2a direction, it is possible to make the structure of the entire apparatus and simple. (3) Since the core die 2a has a simple structure in which the shaft body 452 is rotatably supported via the bearing 6, the core die 2a can be downsized. That is, a small molded product can be precisely molded.

[0068] (4) Since the core mold body 41 is removable from the shaft portion 43, can be freely changed and the thickness of the molded article by changing the core mold body 41 with different diameters. Therefore, by exchanging the core type main body 41, it is possible to perform compression corresponding to the amount of shrinkage according to the resin. (5) Since the hydraulic cylinder that advances and retracts the advancing and retracting member 43 and the compression structure part such as the core mold 2a are completely isolated from each other, there is no influence on the molded product due to oil leakage and maintenance is easy. .

[0069] (6) Since so as to control the forward and backward member 43 in the hydraulic cylinder, together with the adjustment of eccentricity of the core type 2a can be easily and accurately detect the internal pressure of the resin to be compressed during the compression operation Since the amount of eccentricity can be optimally controlled, it is possible to reduce the load on the core mold 2a. Also, core type 2
Even when a large load is applied to a, a quick response can be taken by returning the core mold 2a by switching the hydraulic circuit.

[0070] (7) it is possible to control the rotational speed by the electric motor 48, eccentricity by a hydraulic cylinder (i.e., degree of compression) can be controlled, and it is correct roundness. (8) Angular pin 431 and angular hole 442
Since it has a rectangular shape, it is possible to increase the rotational torque, and it is possible to move smoothly due to the sliding structure.

[0071] (9) is provided with the outer mold 3, the core mold 2
As a result, reliable shaping can be performed with a, and the appearance of the inner and outer surfaces of the mouthpiece forming portion 51 can be improved.

FIG . 6 shows another embodiment of the molding apparatus according to the present invention. As shown in FIG. 6, the molding apparatus 1b includes a ring-shaped divided body 22, 23, 24, in which the core die 2b is divided in the axial direction into portions having different outer diameters.
25, each divided body 22, 23, 24, 2
The molding apparatus 1a is the same as the above-described molding apparatus 1a, except that the respective shafts 5 are individually rotatably supported by the shaft body 452 via the bearings 6.

[0073] Since the molding device 1b is configured as described above, even when the difference in diameter between the large diameter portion and a small diameter portion of the core mold 2b is large, twisting the inner surface of the undercut portion Wrinkles do not occur. That is, if the difference between the large diameter portion and the small diameter portion is large, when the core mold is formed integrally, for peripheral speed of the large diameter portion and the small diameter portion are largely different, or the large-diameter portion of the receiving molding section Twisting or wrinkling may occur on the surface where the small diameter portion contacts, but with the above structure, the large diameter portion and the small diameter portion roll individually,
There are no twists or wrinkles.

In the above embodiment, the resin pipe 5a side is slid to the core mold 2a side. However, the resin pipe 5a is clamped in advance and the resin pipe 5a is
The structure may be such that the core mold and the outer mold parts move forward and backward. In the above-described embodiment, the angular pin 431 is provided on the advancing / retreating member 43 side and the angular hole 442 is provided on the slide block 44, but they may be reversed. Of course, if the core type can be eccentrically revolved, it is not necessary to have the structure of the core type eccentric revolution mechanism described above.

FIG . 8 and FIG. 9 are enlarged views of essential parts showing an example of the molding apparatus according to the third aspect . As shown in FIGS. 8 and 9, this molding apparatus is provided with a plurality of pairs of external gears 582a and internal gears 581a having different modules, and these external gears 582a and internal gears 581a are detachable. .

[0076] That is, external gears 582a, as shown in FIG. 8, and has a bottomed cylindrical shape, have a gear portion 583 is provided along the inner wall surface of the cylinder, the center of the drive shaft 54 is bottom 584 And a bottom portion 584 provided so as to close the motor 53 side of the core mold 2c.
The core mold 2 through the nut 585 while being received by
It is designed to be detachably attached to c.

The internal gear 581a, as shown in FIG.
It is detachably attached to the tip of the arm 56 via a nut 561 and rotates together with the sprocket 572a. Although not shown, the arm 56 is detachable from the drive shaft 54.

[0078] Therefore, the internal gear 581a, remove the chain 59 as a driving force transmitting means, if Yurumere the nut 561, it is possible to easily removed and replaced. On the other hand, the external gear 582a can be easily removed and replaced from the tip of the drive shaft 54 by loosening the nut 583 after removing the chain 59 and the arm 56.

As described above, this molding apparatus has a plurality of pairs of external gears 582a and internal gears 581 having different modules.
Since a and a are provided and can be exchanged, the rolling speed of the core die 2c and the compression force by the core die 2c can be changed without exchanging the core die 2c.

[0080] That is, if the external gears is fixed to the core mold, the high viscosity of the filled resin, or the amount of compression is large,
Alternatively, if molding is performed as it is when molding a thick product, the compression force of the molten resin by the core mold will be a burden, which may cause damage or failure of the mold due to large stress on the gear itself or large load on the motor. However, if the core mold is replaced according to the viscosity of the resin, the amount of compression, the thickness of the molded product, etc., it takes a long time to replace it, and a large adjustment is required for each replacement. For example, the external gear 58
2a and the internal gear 581a need only be replaced,
The above problems also disappear. Also, the load on the motor can be reduced.

[0081] To be more specific, circumscribed gear 5 in the following manner
By replacing 82a and the internal gear 581a,
The viscosity of the resin can be adjusted, the amount of compression can be adjusted, or the thickness of the product can be adjusted. (1) When a high-viscosity resin is used, the torque of the motor 53 is increased by using the external gear 582a and the internal gear 581a of a small module, and the motor 53 can be compressed with a large force.

[0082] (2) often the compression amount of the filling resin, by decreasing the module, raise the torque of the motor 53 can be compressed with great force. At this time, the amount of eccentricity of the core mold 2a is also adjusted. (3) When the molded product has a large wall thickness, the torque of the motor 53 is increased by compressing the module so that it can be compressed with a large force.

[0083]

EXAMPLES Examples of the present invention will be described in more detail below.

[0084] (Example 1) nominal diameter 50mm as tubular molding material (inner diameter 48 mm)
2A in which a hard vinyl chloride resin pipe 5a of No. 1 and a molding apparatus 1a as shown in FIG. 1 are prepared, and a receiving opening 51 having a rubber groove groove 52 on the inner surface is provided under the following molding conditions. A straight pipe 5 with a single socket as shown was molded. The core type 2
The control of the eccentricity amount of a was switched by feeding back the value of the temperature sensor. Heating temperature: 120 ° C Heating time: 10 minutes Mold temperature: 110 ° C Core type eccentric revolution time: 10 minutes Core type eccentricity: 14 mm Core type revolution speed: 30 rpm

[0085] (Example 2) nominal diameter 50mm as tubular molding material (inner diameter 48 mm)
The polyethylene resin pipe 5a and the molding device 1a as shown in FIG. 1 are prepared, and the single-sided reception as shown in FIG. 2 (a) is provided with the receiving opening having the rubber ring groove on the inner surface under the following molding conditions. The straight pipe 5 with a mouth was molded. The control of the eccentricity of the core mold 2a was switched by feeding back the value of the temperature sensor. Heating temperature: 135 ° C. Heating time: 15 minutes Mold temperature: 120 ° C. Core type eccentric revolution time: 10 minutes Core eccentricity: 14 mm Core type revolution speed: 25 rpm

[0086] and stored in the above Examples 1 and 2 obtained in the socket-pipe the respective post processing temperature 23 ° C. Room, pipe end as A (starting point shown in FIG. 2 (a) to 1 hour after processing From 10mm), B (25m from the pipe end as a starting point)
m), C (60 mm from the pipe end as the starting point), and D (100 mm from the pipe end as the starting point), the inner diameter and the outer diameter were measured at each of 6 points in the circumferential direction shown in FIG. 2 (b). When the difference between the maximum value and the minimum value of the measured values was determined as the roundness, the roundness was 0.1 in the case of a hard vinyl chloride resin pipe with a single socket formed by using a conventional petal core.
While the roundness was 8 mm, the roundness was 0.3 mm in the case of the hard vinyl chloride resin pipe with a single socket of Example 1. In addition, the polyethylene resin pipe with a single socket of Example 2 is slightly inferior to the cut product, but with a single socket by molding the socket by conventional injection molding and fusing the socket with the straight pipe part. The roundness was 0.2 mm as in the case of the polyethylene resin pipe.

[0087] Further, by cutting the rubber ring concave groove 52 portion is undercut portion in the axial direction, the measured depth of the groove in its cross-section, in straight tube 5 of any of Examples 1 and 2 Also, good dimensions were obtained. Also,
The appearance of the inner surface was also good with no twists or wrinkles, there were no mold marks, and the transferability was good, and there was no need for secondary processing such as cutting.

[0088]

EFFECT OF THE INVENTION Since the method for manufacturing a tubular molded product according to the present invention is configured as described above, it is provided with the socket molding portion having the undercut portion on at least a part of the inner surface.
It is possible to mold a straight pipe with a single socket with high precision and high appearance.

Further , since the tubular molding material is clamped by the outer mold, the tubular molding material is not displaced during the molding process and the socket molding portion can be reliably molded at a predetermined position. it can. In addition, a large force is not required for inserting the core mold into the tubular molding material or withdrawing the core mold from the mouth molding part.

[0090] Furthermore, crystallinity of advances, it is possible to obtain a more strength excellent moldings.

[0091] On the other hand, the molding apparatus according to the present invention and claims 3, which is configured as described above, at least a cylindrical molded article having a receptacle shaped portion having an undercut portion in a part of the inner surface It can be molded with high precision and high appearance. Moreover, since the structure can be simple , the manufacturing cost can be reduced and the maintenance cost can be reduced.

Further, according to the molding apparatus of claim 4 ,
It is possible to easily change the external gear and the internal gear of different modules. That is, by exchanging the external gear and the internal gear, a stable compression force can be obtained even if the resin viscosity, the product thickness, and the compression amount change. Moreover, since the compression force is stable, the dimensional accuracy is maintained and improved. Further, the load on the motor can be reduced by selecting the external gear and internal gear of the module according to the resin viscosity, the molded product thickness, and the compression amount.

[Brief description of drawings]

FIG. 1 is a view of a straight pipe forming apparatus 1 with a single socket according to the present invention.
It is a sectional view showing one embodiment.

FIG. 2 is a cross-sectional view of a straight pipe with a single socket formed by using the forming apparatus of FIG.

3 is a sectional view of a core mold of the molding apparatus of FIG.

4A and 4B are explanatory views illustrating a method of molding a straight pipe with a single socket using the molding apparatus of FIG. 1 in order of steps.

5A and 5B are explanatory diagrams sequentially explaining the steps subsequent to the step of FIG.

FIG. 6 is a cross-sectional view of essential parts showing another embodiment of a straight pipe forming apparatus with a single socket according to the present invention.

FIG. 7 is a cross-sectional view showing an essential part of a straight pipe forming apparatus with a single-ended opening according to the present invention .

8 is a plan view of the engagement portion of the internal gear and external gears of the molding apparatus shown in FIG.

[Explanation of symbols]

1a, 1b Molding device 2a, 2b, 2c Core type 3 Outer type 31 Split type 4 Core type eccentric revolution mechanism 5 Straight pipe with one side receiving port (cylindrical molded product) 5a Resin pipe (cylindrical molding material) 51 receiving port Molding portion 52 Rubber groove for groove (undercut portion) 55 Processing portion 581a Internal gear 582a External gear

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-47-3445 (JP, A) JP-A-54-130683 (JP, A) JP-A-53-121881 (JP, A) JP-A-56- 60213 (JP, A) JP-A-57-178815 (JP, A) JP-B-3-63500 (JP, B2) European patent application publication 545080 (EP, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 57/04

Claims (4)

(57) [Claims] 1. A mouthpiece molding having an undercut portion on its inner surface.
In a method for producing a straight pipe with a single socket having a portion, a core mold having an outer surface shape substantially corresponding to the inner surface shape of the mouth molding portion, an inner diameter of a tubular molding material larger than the maximum diameter portion of the core mold. Core die insertion step of relatively moving the core die in the axial direction relative to the insert portion , and at least an inner surface shape substantially corresponding to the outer surface shape of the mouthpiece forming portion
And has two or more parts that can be assembled in the axial direction.
Assemble an outer die consisting of a split die and attach the processing part to the outer die.
An outer die mounting step of surrounding the outer die with a molding material heating step of heating at least the working portion of the tubular molding material to make it into a deformable state, and an outer peripheral surface of the working portion with an inner peripheral surface of the minimum diameter portion of the outer die. Clamp
Te while fixing a cylindrical molded material, while maintaining grounds eccentric parallel state with respect to the central axis of the socket forming portion to be molded a central axis of the core type, the socket forming part to be molded core mold A molding step of revolving around the central axis and compressing the processed part on the outer surface of the core mold in the outer peripheral direction of the tubular molding material to form the mouthpiece forming part, and a crystallization start temperature at a cooling rate with a predetermined temperature gradient. Cool
And the crystallization start temperature after the first step
The second stage of maintaining the temperature and the predetermined temperature after the second stage
Cooling and solidification consisting of a third stage of cooling at a gradient cooling rate
The maximum distance between the process and the outer peripheral surface of the core die from the central axis of the mouthpiece molding part is
Receiving the core mold in a state in which it is larger than the minimum inner diameter of the mouth forming part.
While moving in the direction of the central axis of the mouth forming part, it receives the outer mold.
The distance from the center axis of the mouth forming part to the minimum inner diameter of the split mold is
Divided into a state in which it is larger than the maximum outer diameter of the socket molding part
Later, single socket with straight, characterized in that the socket shaped portion is provided with a releasing step of releasing by relatively moving the piece socket with straight molded in the axial direction of the core type Manufacturing method. 2. A core mold having an outer surface shape substantially corresponding to an inner surface shape including an undercut portion provided in a straight pipe with a single- ended opening to be molded and having a maximum outer diameter smaller than an inner diameter of a tubular molding material. From the outside, it surrounds the processing part that will be the inlet molding part of the tubular molding material.
Assemble freely and take out the socket molding part when dividing
Consists of multiple split types that can be split into at least
An outer surface having an inner surface shape that substantially corresponds to the outer surface shape of the mouthpiece molding portion.
A fixing means for fixing the tubular molding material consisting of a mold, and a receiving part for molding the central axis of the core mold while being surrounded by the outer mold.
While eccentric while maintaining the parallel state with respect to the central axis of the mouth forming portion, an outer form of the inner surface direction of the processing unit by revolving around the central axis of the socket forming portion to be molded core mold with a core mold outer surface To
A core type eccentric orbiting mechanism for compression, and a straight pipe forming device with a single socket , characterized by: 3. The core type eccentric revolution mechanism is
Rolling case, advancing / retreating member, slide block, core type
And a shaft portion that rotatably supports the
Is supported by bearings and transmits the rotational driving force of the electric motor.
And is freely rotatable in the casing.
The advancing / retreating member slides inside the rotating case toward the core mold.
It is freely inserted and its rear end is a hydraulic cylinder.
Is rotatably supported at the rod end of the
The hydraulic cylinder rotates with the rotation of the base.
The core of the rotating case is formed by expanding and contracting the rod of the dar.
It is designed to move back and forth in the direction.
Inclination with respect to the slide shaft of the advancing / retreating member on the surface on the die side
Angular pins are projected on the slide block.
The hook has a connecting pin on the surface on the core mold side, and
The side surface has the same cross-sectional shape and the same angle as the angular pin.
Angular holes that are inclined at
The angular pin is slidably inserted in the hole
And the connecting pin of the slide block is attached to the shaft portion.
3. The fixed structure according to claim 2, wherein the fixed structure is fixed.
A straight pipe forming apparatus with a single-ended opening described in. 4. A core type eccentric revolving mechanism is provided so that its tip faces the inside of the core die from one end of the core die, and a drive shaft rotated by a motor and one end fixed to the drive shaft inside the core die. , An arm that rotates with the rotation of the drive shaft, an external gear that is provided along the inner peripheral surface of the core type, and is rotatably attached to the other end of the arm, and The internal gear is in contact with the internal gear, and the driving force transmission means for transmitting the rotational driving force of the drive shaft to the internal gear is provided. The external gear and the internal gear are detachable, and a plurality of different pairs of modules are used. claims and a circumscribed gear and the internal gear
Item 3. A straight pipe forming apparatus with a single socket according to Item 2 .