JPS60232925A - Forming die for synthetic resin nib - Google Patents

Abstract

PURPOSE:To enable the forming of pen nibs having highly deformed diametric cross section shape by providing a melt speed adjusting aperture having an aperture length and a diameter controlled to enable a melt passage at almost the same speed through each melt shaping aperture against the melt shaping aperture between all the melt shaping apertures of a shaping opening and the interior of a die body. CONSTITUTION:A shaping opening C of a similar form to the diametric cross section of a pen nib having a desired diametric cross section form to be molded is formed in a continuous way through a melt sump B1 and a flow control B located behind, in front of a die A. Melt speed adjusting apertures B2-B4 which exist between all the melt shaping apertures 1 and the melt sump B1 to make both these parts continuous and control melt flow velocity, are opened in such a way that the number of melt speed adjusting apertures 1 is the same as that of melt shaping apertures. Thus the aperture length and diameter of the melt speed adjusting apertures are adjusted to control the melt passage through each melt shaping aperture 1 to the same velocity. Consequently, unfinished tubular pen nibs of a similar cross section to the diametric cross section form of the shaping opening C are extruded from the shaping opening C.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a molding die for a synthetic resin nib to be included in writing implements such as markers and felt-tip pens, and has a highly irregular shape with an enlarged ink-wetted surface. It is related to the forming die used to form the pen tip with a radial cross section.

(Prior Art) FIG. 7 shows a forming die in the manufacturing method proposed in Japanese Patent Publication No. 53-27973.

This molding die 50 has a large number of discharge holes 51 arranged close to each other, and when the molten synthetic resin is extruded and discharged in the form of a filament from each of these independent discharge holes, the expansion of the synthetic resin, that is, the ballast effect, causes , the extruded synthetic resins are partially welded together outside the die, and the ink passages are left in the non-welded areas for molding, which is the so-called outside-the-die self-visual molding method.

Although it is possible to mold a pen nib to a certain extent with this molding die 50, it also has the following drawbacks.

(2) Regarding the degree of machining of the die, the multiple discharge holes provided in the die must be closely spaced from each other. The reason for this is that the envelope of the filament-shaped molten synthetic resin extruded from these discharge holes has a similar shape to the fine voids. This makes the die extremely difficult to manufacture and is disadvantageous in terms of price.

■ Regarding the strength of the die, in order to reduce the degree of irregularity, swell ratio, and surface roughness (hereinafter referred to as melt fracture phenomenon), the length of the discharge holes must be shortened and the distance between each discharge hole must be reduced. The die must be made narrower, which reduces the pressure resistance against the molten resin and shortens the life of the die.

(2) Regarding swell ratio In the case of independent discharge holes, in order to make the swell ratio, which is an important factor in molding, appropriate, the hole length must be constant and a constant extrusion pressure is required. In other words, when the extrusion rate is increased, melt fracture phenomenon occurs1.
In order to achieve this, an optimum extrusion rate is required, and it is difficult to obtain an optimum swell ratio by simply changing the hole length, and the control range for the swell ratio is extremely narrow, making stable molding difficult.

■About the melt fracture phenomenon As the extrusion speed increases, the rate of viscous deformation of the filament discharged from the discharge hole, which is an independent hole, decreases, and conversely, the rate of elastic deformation increases, until the filament becomes an elastic body. This results in fracture-like fractures or surface cracking, which occur at very high extrusion pressures or at very high drawing speeds, which disadvantageously affect the capillary flow rate of the ink.

■About the enlargement rate In the self-adhering method outside the die, the enlargement rate is small because the diameter of the circumscribed circle of the outer filament is large and the circumferential surface of each filament discharged from the discharge hole is cooled. Therefore, there is a limit to the ability to mold smaller diameter pen nibs. In addition, since the drawing ratio is small, it is not possible to increase the diameter of the die, making the processing even more difficult. On the other hand, if the diameter is to be reduced, it is necessary to avoid cracks in various parts of the pen tip cross section. product cannot be obtained.

■Since the degree of crystallinity is measured outside the die, each filament comes into contact with air and its peripheral surface is cooled as soon as it leaves the discharge hole, so the cooling rate is fast and the degree of crystallinity is low (and thermal strain ( degree of shrinkage)
There is a big disadvantage.

■About weld lines Even when each discharge hole is processed and set in an optimal positional relationship, weld lines, which are the joints of each filament, occur at the fused parts of each filament attached to the outside of the die, and the fusion of filaments occurs. It has the disadvantage of being weak in strength and causing cracks to occur.

■ Regarding the degree of freedom of the molding material, the swell ratio is small and the melt index is low.
Materials with high values are unsuitable, and have the disadvantage of limiting the materials that can be molded.

■ Cooling Each filament is individually cooled by air outside the die and cooling is not controlled, so there is a disadvantage that the internal ink passage gap cannot be controlled.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems (1) to (2) all at once, and also adjusts the melt amount at each part of the diameter cross section of the pen tip by adjusting the length and diameter of the melt speed adjustment hole. It is an object of the present invention to freely control everything from adjustment to large adjustment, and to enable molding of a pen nib having a diameter cross-sectional shape with a large degree of irregularity in which the ink-wetted surface, which is similar to the molding opening, is enlarged and extended.

(Means for Solving the Problems) In order to achieve the above-mentioned problems, the present invention has an approximately pipe-shaped contoured opening in the front part of the die in which the air hole is opened, and a plurality of mutually independent openings from the inside of the opening. A shaping opening consisting of a partition shaping opening extending in the direction of the central air hole and a retaining wall shaping opening extending in the circumferential direction from the partition shaping opening is bored and formed with a large number of melt shaping holes communicating with each other, and the shaping opening of each melt-forming hole between all of the melt-forming holes and the inside of the die body.
Melt speed adjustment holes whose length and diameter are controlled so that the melt passing speed can be adjusted to be almost the same are combined with melt shaping holes.
The structure is characterized in that they are provided at a composition ratio of 1:1.

(Function) Each melt constituting each part of the cross section of the pen tip is controlled to the same speed by the melt speed adjustment hole which is freely adjusted from fine to large, and the ink wetted surface is enlarged and the melt has a predetermined porosity with a high degree of irregularity. The pen tip is shaped into a diametrical cross-sectional form having a passageway, and after being shaped in this way, it is extruded from the opening as a pen tip of similar shape.

(Example) An example of implementation of the present invention will be described in detail below based on the drawings.

Dice A has a built-in screw (not shown), and powder 1, particulate ′= falling from a hopper (not shown).
``5'') One reservoir of 8 mel of synthetic resin ``8'' is transferred to 6 flow rate control section B. However, during this transfer, dice A
The synthetic resin is heated from the outside with a heater (not shown) and transferred while melting the synthetic resin.

In addition, the die A is provided with an air blowing pipe A+ and an air feeding path A2 communicating with this blowing pipe, and the air feeding path is passed through the center of the flow rate control part B and the center of the injection part. Then, the air hole A3 is opened on the injection surface. The purpose of the air blowing pipe A+ and the air supply path A2 is to prevent the synthetic resin from concentrating in the center by supplying air and blowing it out from the air hole A3 during the drawing process during pen nib manufacture. The pen nib E is molded.

The die A has a shaping opening C having a shape similar to the diameter cross section of the pen tip having a desired diameter cross section to be molded, in communication with the melt reservoir B1 at the rear via the flow rate control section B, on the front part, that is, the injection surface. This shaping opening C includes a roughly vibe-shaped outer shaping opening C2 that is concentric with the air hole A3, a plurality of partition wall shaping openings C1 that extend from the inside of this in the direction of the central air hole A3, and partition wall shaping openings C1. Retaining wall shaping openings C3 extend circumferentially from the left and right sides of C1, and these openings C2, C1, and C3 are subdivided and arranged into a large number of melt shaping holes 1 communicating with each other.

The roughly pipe-shaped outer shaping opening C2 is shown in the drawing as having a total of 144 melt shaping holes 1, 48 for each of the inner, middle, and outer rings.
. . are formed by opening them in a manner that they communicate with each other, and the opening space is subdivided into 144 blocks that communicate with each other.

The partition shaping opening C+ communicates with the inside of the outer contour shaping opening C2, and extends equiangularly from three sides of the inside toward the central air hole A3, and this partition shaping opening C+ communicates with the inside of the outer contour shaping opening C2. are drilled so that they communicate with each other, and are subdivided into four blocks that communicate with each other.

The retaining wall shaping opening C3 communicates with the left and right sides of the partition wall shaping opening C1, extends in the circumferential direction, and is arranged in parallel at equal intervals in the radial direction, including an inner retaining wall shaping opening c1, an intermediate branch wall shaping opening C2, and an outer branch. The inner retaining wall shaping opening C1 is 1.
The number of melt-shaped holes 1 is formed. Intermediate retaining wall shaping opening C2
is by drilling three melt-forming holes 1 in communication with each other,
It is subdivided into three blocks that communicate with each other. The outer branch wall shaping opening C3 is formed by forming five melt shaping holes 1 in communication with each other and subdividing into five blocks communicating with each other.

Outline shaping opening C2, partition shaping opening C1, retaining wall shaping opening C
3, the diameter of the melt-shaped hole 1 that forms the outer contour-shaped opening C2 and the partition-shaped opening C1 gradually decreases toward the center, and the diameter of the retaining-wall-shaped opening C3 is made the same, and the diameter of the melt-shaped hole 1 that forms the flow control part B The melt, whose flow rate is controlled, is fused into the same body and shaped into the same shape within these openings, and then extruded, so that the diameter cross section of the tubular nib body that is then stretched is similar to the diameter cross section of the shaping opening C. The shape of the ink wetting surface is such that the ink wetting surface has an ink passage with a favorable capillary function extending with equal spacing. Therefore, in principle, the diameter of the melt shaping hole 1 gradually decreases from the outside to the center of the contour shaping opening C2. However, the invention is not limited to this, and depending on the diameter cross-sectional shape of the pen nib to be molded, the outer molding opening C2 and the partition molding opening C1 may be made to have a J diameter, or the middle including the branch wall molding opening C3 may have a small diameter. It goes without saying that various modifications may be made, such as forming the shape with a large diameter.

As shown in the drawing, the flow rate control part B is a melt speed adjustment hole that is interposed between all the melt shaping holes 1 and the melt pool B1 to communicate them and control the melt flow rate. is the melt speed adjustment hole B2 for the melt shaping hole 1 in the outer contour shaping opening C2, the melt speed adjustment hole B3 for the melt shaping hole 1 in the partition wall shaping opening C+, and the melt speed adjustment hole B4 for the branch wall shaping opening C3. As shown in
All the melt forming holes 1 are drilled in the same number as the melt forming holes 1, that is, in a one-to-one relationship, and the diameter relationship with all the melt forming holes 1 is slightly smaller considering the me/reto balance phenomenon. is formed. And each melt speed adjustment hole B2, B
3, B4 is the outer contour shaping opening C2 and the partition shaping opening C+
and branch wall shaping openings In order to control the melt passing speed in all the melt shaping holes 1 of block 210 in the same way on the drawing in C3, the hole length and diameter of each melt speed adjusting hole are adjusted to each melt shaping hole. It is set in relation to the local area of B1 and in consideration of the laminar flow phenomenon of the melt in the melt pool B1. Specifically, the length and diameter of the melt-formed hole 1 with a large local area are managed to be shortened and expanded, and the hole length and diameter of the melt-formed hole 1 with a small local area are controlled. By managing the expansion and contraction of the diameter and controlling the passage speed of the melt in each melt shaping hole 1 to be the same, the tubular nib body with a diameter cross-sectional shape similar to the diameter cross-sectional shape of the shaping opening C is shaped into the shaping opening. It is formed so that it can be extruded from part C.

The relationship between the control of the hole diameter and hole length of each melt speed adjustment hole 82, B3, and B4 is based on the flow phenomenon that the extrusion amount is approximately proportional to the fourth power of the hole diameter and inversely proportional to the hole length. To greatly adjust the melt flow rate,
The hole diameter is intensively controlled, and the melt flow rate is delicately adjusted by intensively controlling the hole length. Manage both.

Therefore, all the melt shaping passages 1 are formed in the shape of a chain of connected circles, but it is the pen tip E that is formed in this way.
By subdividing the shaping opening C, the amount of melting in the outer shaping opening C2, the partition wall shaping opening C1, and the branch wall shaping opening C3, and the melting amount in each opening C3, C2, and CI can be reduced. In addition, the cross-sectional shapes of the partition wall E2 and the retaining wall E3 are determined to be faithful to the shapes of the partition wall shaping opening C1 and the branch wall shaping openings C and 3, and the ink passage is This is to keep E4 constant within the limit where capillary action is likely to occur. That is, the melt extruded while being controlled at the same speed by each melt speed adjusting hole 82, Bs, B4 expands in the melt shaping hole 1 and advances at the same speed as the melt in the adjacent passage. After being fused and integrated and shaped through the contour shaping opening C2, the partition wall shaping opening C1, and the branch wall shaping opening C3, it is extruded from the shaping opening C to form a pen nib E with a predetermined porosity. .

Further, the protrusion C4 in the contour shaping opening C2 forms an ink groove Es in the outer wall E1 of the pen nib E, so that the outer wall E1 is clearly colored in the same color as the ink in the ink groove E5. This protrusion C4 may be omitted, and in this case, a pen nib E having a radial cross-sectional shape without an ink groove E5 is formed.

The pen nib E manufactured using the above-mentioned die has a diametrical cross-sectional shape as shown in FIG. The ink passages E are formed by extending in the centripetal direction, respectively, and branch walls E3 are formed to extend symmetrically and circumferentially from the left and right sides of each partition wall E2, and the ink passages E are formed by the envelopes of these molds.
4 is constituted by a circumferential passage E4a and a radial passage E4b communicating with each other at the center.

The advantages of this pen nib E are: ■ It eliminates the writing directionality around the axis at the writing angle where the concentric ink passages are formed, while the radial ink groove connects each of these concentric ink passages at the shortest distance, allowing mutual interaction. It aims for rapid distribution and eliminates the restriction on the writing angle that changes variously during writing, and copes with the various writing angles and directions around the axis of each person, changes in these during writing, and differences in writing speed. As a result, a handwriting of a constant thickness can be obtained from the beginning of the calligraphy to the end of the calligraphy.

■ All the ink passages, partition walls, and branch walls are arranged symmetrically on the left and right sides of the center line, and the strain during cooling, which is unique to synthetic resin during molding, is balanced on the left and right sides, and the partition walls,
There is no abnormal shape of the branch wall, and therefore the ink passage exhibits an appropriate porosity similar to that of the mold, ensuring the above-mentioned handwriting. At the same time, the symmetrical partition walls and branch walls on the left and right sides of each center line have uniform bending stress in response to various writing pressures around the axis, and the symmetrical partition walls and branch walls on the left and right sides of each center line have uniform bending stress in response to various writing pressures around the axis. The bending stress, or stiffness, provides a consistent writing feel on any writing surface around the axis.

(2) Wall surface roughness forming the ink passage does not occur even under extremely high extrusion pressure or molding speed at extremely high drawing speed, and is a smooth wall surface that is not disadvantageous to ink flow.

It is self-adhered within the O-die, has a slow cooling rate, high crystallinity, and small thermal strain.

- It is integrally molded within the die, and there are no weld lines or cracks that can reduce strength.

■ The ink passage is extruded into a tubular shape and is internally cooled.
It is formed while cooling is controlled and exhibits a desired controlled cross-sectional shape.

The above embodiment is an example of the present invention, and within the scope of the present invention, the partition wall shaping openings C1 may be joined at the center, or the ends of the wave shaped shaping openings C3 may be diagonally opposed to each other. ,
Furthermore, each of the retaining wall shaping openings C3 is inserted in an intersecting manner, leaving a gap for an ink passage, and the retaining wall shaping openings C3 are
3 on only one side of the partition shaping opening C1 can be freely arranged in accordance with the difference in the diametrical cross-sectional shape of the pen point to be formed.

Also, the relationship between the melt shaping hole and the melt speed adjustment hole is 1.
The premise is to have a one-to-one mutual relationship, and other desirable conditions within this premise are first to make the diametrical cross-sections of both holes similar in shape, and second, to make the diametrical cross-sections of both holes similar in shape. It is to have a circular shape.

(Effects of the invention) ■ Regarding the degree of processing, the distance between the melt forming holes forming the tubular shaping opening does not have to be as strict as the discharge holes of the die in the filament method. The tolerance range is extremely wide, so the difficulty of manufacturing the die is extremely low, and it is also advantageous in terms of price.

■Strength Because it is a tubular system, the flow rate and shaping are controlled by the double holes of the melt shaping hole and the melt speed adjustment hole. As with the filament focusing method, in order to deal with the degree of irregularity, swell ratio, and melt fracture phenomenon, the length of the independent discharge holes must be shortened and the interval between each discharge hole must be narrowed. As a result, the wall surrounding each melt shaping hole that communicates with each other in the radial direction is reinforced by the base part that forms the melt speed adjustment hole, and has strong pressure resistance against molten resin.
Long lifespan of dice.

■About swell ratio Since the tubular system uses double holes for melt shaping and melt speed adjustment to control flow and shaping, the rate of change in melt extrusion pressure and extrusion amount can be adjusted, and the swell ratio can be adjusted. The control area can be expanded, and stable molding can be performed over a wide range of molding areas.

■ Melt fracture phenomenon Because it is a tubular and double-hole system, the critical shear rate of the melt is high, and surface cracks do not occur even at high extrusion speeds with high productivity, and there is no disadvantage in ink flow rate.
It is possible to control the condition of the surface (ink wetted surface) that affects the capillarity phenomenon that is essential for a pen tip under high productivity.

■About the enlargement rate Since the die is self-adhesive and has an internal cooling system, the enlargement rate is large and it is possible to form a pen tip with a smaller diameter, while the die can be made larger in diameter and its shaping opening It also has the advantage of being easier to process.

■Crystallinity Since it is a self-adhering method within the die and an internal cooling method, the cooling rate is slow, and the advantage is that the crystallinity is high and thermal strain is small.

■About the weld line Because it is a self-adhesive method in a die that extrudes into a tube shape,
It is strong because it does not have weld lines, which can cause cracks, unlike the die-extrusion method in which filler melt is extruded, bundled, and molded.

- Degree of freedom for molding materials Even materials with a low swell ratio and high melting index can be made larger than the swell ratio of the resin itself, and can be molded into a diameter cross-sectional shape that matches the shaped opening. Therefore, there is an advantage that the molding material is not limited.

■ Cooling Since the internal cooling system allows for centralized control of cooling of the wall surface forming the ink passage, it has the advantage of being able to freely control the gap between the ink passages.

[Co., Ltd.] About adjusting the melt flow rate at each part of the cross section By adjusting the length and diameter of each melt speed adjustment hole, you can freely adjust and manage the melt flow rate from subtle to large adjustments. It is possible to finely or greatly adjust the melt to an optimum position in accordance with the area of each part of the diametrical cross-section of the pen tip, which differs in size.

■ The pen nib has a diametrical cross-sectional shape with a retaining wall that has an enlarged ink coating surface and a high degree of irregularity.The melt flow velocity at each part of the shaping opening is controlled by the melt speed adjustment hole to make the mass of melt uniform at each part of the cross-section. Thus, it is possible to continuously manufacture the diameter cross-sectional shape that is faithful to the shape of the opening.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the molding die of the present invention. Figure 2 is a vertical sectional side view taken along the line ■-■. Figure 3 is a vertical cross-sectional side view taken along the line ■-■. FIG. 4 is a sectional view showing the radial cross-sectional shape of a synthetic resin pen nib, which is a shaped product. Fifth
FIG. 6 is a radial cross-sectional view showing an example of another moldable pen nib. FIG. 7 is a front view of a conventional die. In the figure, A is the die A3 is the air hole B2, B3, B4 is the melt speed adjustment hole C is the shaping opening C1 is the partition shaping opening C2 is the contour shaping opening C3 is the retaining wall shaping opening 1 is the melt shaping hole Patent applicant Thibaud Co., Ltd. Company Figure 3 Figure 5 Figure 7 Procedure Amendment January 1982! 7th 1. Indication of the case 1988 Patent Application No. 90709 2. Name of the invention Molding die for synthetic resin nib 3. Relationship to the case by the person making the amendment Name of the patent applicant (Name) Thibaud Co., Ltd. 4, Agent Person Address: Hayakawa Building, 5-14-7 Hakusan, Bunkyo-ku, Tokyo Telephone: Tokyo (m) 0531 (Representative) Date: 7, 1925 Contents of the amendment: Attachment amendment letter L Page 2, line 20 of the specification After "densely", "and accurately placed" is added and corrected. 2 Add "extrusion pressure" after "resin" on page 8, line 10 of the same book. a From page 4, line 12 to page 5, line 1 of the same book are amended as follows. Since all of the filaments discharged from the discharge holes using the self-adhering method outside the die are cooled by contacting the air at the same time as the circumferential surface thereof is discharged, the solidification speed of each filament is increased. Therefore, the enlargement ratio is small, and there is a limit to the ability to form smaller diameter pen nibs. On the other hand, if attempts are made to reduce the diameter, cracks will inevitably occur in various parts of the pen tip cross section, making it impossible to obtain a product. In addition, since the enlargement ratio is small, if you want to make the pen tip smaller in diameter, you will also need to make the die smaller in diameter, which has the disadvantage of making the processing even more difficult. Before the line ``Cooling management'', write ``For the entire ink passageway''
Add and correct. 5. Add "with the opening" after "from the opening" on page 7, line 11 of the same book. 6 In the same book, page 10, line 14, "stretching" is corrected to "enlargement." 7 Correct "molding" to "shaping" in lines 2, 8, and 4 on page 11 of the same book. Add "extrusion pressure" after "resin" on page 18, line 14 of the same book. to correct. a Correct "There is." on page 19, line 20 of the same book cylinder to "It can be used as a nib." 1α Correct "filament" in line 8 of page 20 of the same book to "filament". IL On the 7th line of the same page in the same book, `` deru.'' can be used as the [na nib. ]. 12 Correct “paint” to “i!lre” on page 21, line 5 of the same book. la Correct "orthopedic product" in line 15 of the same page of the same book to "molded product". 14. Amend the claims in the same document as attached. Claims: The front part of the die in which the air holes are opened includes a generally pipe-shaped outer contour shaping opening, a plurality of partition shaping openings extending from the inside of the opening toward the center independently, and a plurality of partition shaping openings extending in the circumferential direction from the partition shaping opening. A shaping opening constituted by an extending retaining wall shaping opening is bored and formed with a large number of melt shaping holes in communication with each other in the radial direction, and between all melt shaping holes of the shaping opening and the inside of the die body. A molding die for a synthetic 1111 nib, which is provided with melt speed adjusting holes whose lengths and diameters are controlled so that the melt passing speed of each melt shaping hole can be adjusted to be almost the same.

Claims (1)

[Claims] The front part of the die in which the air hole is opened includes a roughly pipe-shaped outer contour shaping opening, a plurality of partition shaping openings extending from the inside of the opening toward the center independently, and a retaining wall extending in the circumferential direction from the partition shaping opening. A large number of melt forming holes are formed in communication with each other in the radial direction, and each melt forming hole is formed between all of the melt forming holes of the forming opening and the inside of the die body. A molding die for a synthetic resin nib, which is provided with melt speed adjustment holes whose lengths and diameters are controlled so that the melt passing speed and thickness can be adjusted to be almost the same.