JP6179223B2 - Ballpoint pen manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a ball-point pen tip, in which a ball-point pen tip having a front-side small-diameter portion and a rear-side large-diameter portion is processed with a pressing force from the rear.

Conventionally, as a minimum form as a writable ballpoint pen, an ink storage tube is directly or on the opposite side of the ballpoint pen tip that holds the ball in a state where the ball is partially protruded from the tip opening, or a connecting member. There is a so-called refilling form that is fixed through.
Japanese Patent Application Laid-Open No. 8-244394 (Patent Document 1) discloses that a ball-point pen member is incorporated in the ball-point pen tip to prevent the ink in the ball-point pen tip from drying, and the ball-point pen tip is used for rearward regulation of the ball-point member. There is disclosed a refill in which a caulking process for reducing the diameter of the rear end is performed, a connecting member is fixed to the rear thereof, and an ink storage tube is fixed to the rear of the connecting member.

JP-A-8-244394

For ballpoint pen tips that have an inclined shape that decreases from the rear large-diameter portion toward the tip toward an acute angle, such as installing a spring, when performing processing that involves pressing from the back, such as a ballpoint pen tip The holder member that receives and supports the inclined portion cannot be formed with the same angle between the tip inclined surface angle of the ballpoint pen tip and the inner wall opening angle of the inclined hole of the holder member. In addition, even if it can be machined to the same angle as the standard tip inclined surface angle of the ballpoint pen tip, the tip inclined surface angle of the mass-produced ballpoint pen tip varies, and the inner wall opening angle of the inclined hole of the holder member and the ballpoint pen A chip whose tip inclined surface angle does not match is generated. As a result, deformation due to the amount of pressing increases the circumferential surface contact state, the ballpoint pen tip bites on the holder member, and a circumferential scratch is generated on the ballpoint pen tip.
Further, in the case of processing with a higher pressing force, the wedge member is further bitten by the wedge action, and scratches grow into burrs. When such a refill is attached to the knock type ballpoint pen exterior, when the ballpoint pen tip tip appears and disappears from the exterior due to the knocking operation, the burrs generated on the inclined surface of the tip of the ballpoint pen tip may hit the exterior inner wall surface and impair sliding performance. is there.
Furthermore, assuming that a certain amount of biting occurs, it is possible to add a step of lifting the ball-point pen tip from the ball side of the ball-point pen tip and releasing the biting when biting occurs, but the productivity decreases. .

  The present invention provides a ball-point pen tip manufacturing method in which a ball-point pen tip having a front-side small-diameter portion and a rear-side large-diameter portion in its outer shape is processed with a pressing force from the rear. The opening angle of the inner wall of the mortar-shaped inclined hole of the holder member is more acute than the inclination angle of the line connecting the small-diameter portion and the large-diameter portion of the outer shape of the ball-point pen tip, and the large diameter of the mortar-shaped inclined hole of the holder member The gist of the manufacturing method of the ballpoint pen tip is that the inner diameter of the opening is larger than that of the rearward large diameter portion of the ballpoint pen tip.

When processing with a pressing force from the back of the ballpoint pen tip, the inner wall opening angle of the mortar-shaped inclined hole of the holder member is larger than the inclination angle of the line connecting the small diameter portion and the large diameter portion of the external shape of the ballpoint pen tip. Due to the acute angle, the inclined surface which is a line connecting the small diameter portion and the large diameter portion of the outer shape of the ballpoint pen tip does not hit the small diameter opening of the holder member. Further, the inner diameter of the large-diameter opening portion of the mortar-shaped inclined hole of the holder member is larger than the rear-side large-diameter portion of the ball-point pen tip, so that the rear-side large-diameter portion of the ball-point pen tip is a mortar-shaped portion of the holder member. Since it hits the inner wall of the inclined hole, the inclined surface of the ballpoint pen tip does not hit the large-diameter opening of the holder member. Therefore, even if the ball pen tip is pushed in with a strong processing strength and the large-diameter portion of the ball-point pen tip is somewhat reduced in diameter, the state where the large-diameter portion is basically grounded to the inclined surface of the mortar-shaped inclined hole of the holder member is maintained. Since the pressing contact area does not increase, the ball-point pen tip and the holder member can be prevented from biting.
In addition, even if burrs are generated in the rear due to the circumferential slip at the intersection of the slanted outer surface of the ballpoint pen tip and the rear large-diameter part, the problem is minimized because there is little contact with other members. Is done.
Therefore, the ballpoint pen tip does not bite on the holder member, the appearance is not impaired, the step of releasing the bite is unnecessary, the reduction in productivity is suppressed, and even if it is applied as a knock type ballpoint pen, it does not cause poor sliding. .

The longitudinal cross-sectional view by which the ball-point pen tip was inserted in the holder member of this invention. The longitudinal cross-sectional view of the ball-point pen tip manufactured by this invention. The longitudinal cross-sectional view of another type of ball-point pen tip manufactured by this invention. The longitudinal cross-sectional view which performs the process accompanying pressing force with the holder member of this invention.

The ball-point pen tip manufacturing method of the present invention is formed by processing the ball-point pen tip and its constituent members in a fixed state and forming a ball-point pen tip or a refill provided with the ball-point pen tip.
In other words, the manufacturing method is basically performed by combining the holder member that holds the ball-point pen tip in a fixed state with a processing tool or a processing machine that performs various processing. The details of machining are not limited in any way other than machining with a pressing force from the rear, and can be applied.

The holder member used at the time of such processing is used for fixing the ball-point pen tip during processing to increase processing accuracy.
The holder member has a mortar-shaped inclined hole as a direct installation site of the ball-point pen tip. The inclined hole may be a member in which a hole is simply formed, or may be a chuck that forms a mortar-shaped inclined hole by forming a space as a result of combining a plurality of divided members.
The large-diameter opening of the mortar-shaped inclined hole of the holder member that receives and fixes the ball-point pen tip is formed on a larger diameter than the rear-side large-diameter portion of the ball-point pen tip because it is on the side where the ball-point pen tip is inserted. It faces the small-diameter opening of the inclined hole and is formed at an acute angle with respect to the inclination angle of the line connecting the small-diameter portion and the large-diameter portion of the outer shape of the ballpoint pen tip.
The inner wall opening angle of the mortar-shaped inclined hole of the holder member is 5 ° or more with respect to the axial center than the inclination angle of the ball-point pen tip to be processed (the inclination angle connecting the large-diameter portion and the small-diameter portion). Since the rear large-diameter portion hits the inner wall of the mortar-shaped inclined hole of the holder member, there is a concern that the wedge action will not occur, but the wedge effect is easy to work and pushed in, so it will be excessively pinched Therefore, the angle is preferably set to 0.5 ° to 1 °. If it is an acute angle of 5 ° or more, the intersection of the inclined surface of the ballpoint pen tip and the rear large-diameter portion will slip around the circumference, and if the pressing load during processing is high, the meat will protrude from the rear large-diameter portion, When mounted on a knock-type ballpoint pen exterior, the knocking operation may impair the slidability when the tip of the ballpoint pen tip protrudes from the exterior.
Further, due to the processing distortion caused by the cutting blade when the radial groove communicating with the inner hole serving as the ink inflow path into the ball holding chamber is divided into the circumferential shape substantially equally at the inward projecting portion of the ballpoint pen tip, Since the bulge is generated in the vicinity of the radial groove processing portion of the inclined surface of the outer shape, even if the inner wall opening angle of the mortar-shaped inclined hole of the holder member is formed at an acute angle than the inclined angle of the ball pen tip inclined surface In addition, there is a risk that the outer peripheral portion near the radial groove machining portion abuts against the inner wall of the inclined hole of the holder member, leading to the occurrence of biting, and the inner diameter of the small-diameter opening of the mortar-shaped inclined hole of the holder member is the radial It is preferable to set the inner diameter at which the outer shape portion near the groove processing portion does not contact.

As the material of the holder member requires hardness, carbon tool steel, carbon steel for machine structure, chrome steel, nickel chrome steel, nickel chrome molybdenum steel, chrome molybdenum steel, die steel, alloy tool steel, martensite series Stainless steel etc. can be used.
In addition, because the holder member does not require toughness and importance is attached to wear resistance and corrosion resistance due to repeated use in mass production, the martensitic stainless steel SUS440C has a high carbon content and can provide high strength and high hardness by heat treatment. Is preferably used.
And since such abrasion resistance is regarded as important, it is necessary to increase the hardness to about HRC 50 to 60 by heat treatment. There are electric furnaces, gas furnaces, salt bath furnaces, and vacuum furnaces for hardening to increase hardness. In a salt bath furnace heated in a salt bath or a vacuum furnace heated in a vacuum furnace, an oxide film is formed. Therefore, an immersion step in an acid solution for removing the oxide film is unnecessary, and there is no erosion damage to the holder member. However, in a salt bath furnace, if there is residual salt that could not be completely removed by washing and hot water after heat treatment, the residual salt absorbs moisture and there is a risk of rusting. Is also preferable.

As a processing method of the mortar-shaped inclined hole of the holder member, there are a lathe process using a cutting blade formed at a taper angle that is an opening angle of the inner wall of the inclined hole, and an electric discharge process using an electric discharge master formed at the taper angle.
Cutting blades used for lathe processing include single-edged half-moon cones and double-edged flat cones, etc., but it was intended that the cones would be swollen or fluctuated depending on the state of chip discharge from the workpiece. It may deviate from the opening angle of the inner wall of the inclined hole.
Electric discharge machining, in which an arc discharge is generated between an electric discharge master, which is an electrode, and the workpiece, and the shape of the electric discharge master is transferred while removing a part of the workpiece, is desirable because of high taper angle accuracy.
In either processing method, it is desirable to finish after roughing in order to increase the taper accuracy. In particular, the machined surface of EDM is in the form of a fine crater. For improvement, by applying intermediate finishing between roughing and finishing as necessary, the dependency on the inner wall finishing of the inclined hole after heat treatment, which will be described later, can be reduced. A change in the opening angle of the inner wall of the inclined hole can be prevented.

A mortar-shaped inclined hole is formed, and the inner wall surface finishing process of the inclined hole is performed in order to remove the processing marks of the inclined hole of the holder member subjected to the heat treatment. There are lapping, buffing, burnishing, chemical polishing, barrel polishing, electromagnetic barrel, etc. as processing methods, but the work and equipment are easy to obtain a smooth surface, suitable for holder members with small diameter. Wrapping is preferred. However, since the holder member is made of the steel described above, loose abrasives used as a lapping agent are not suitable for diamond and silicon carbide because carbon is absorbed by the holder member, which is the material to be polished, and abrasive wear is severe. Corundum-based abrasives whose main material is alumina are suitable.
If necessary, after polishing, an electroplating method is used to form an alloy diffusion layer inside the metal base material, which is completely integrated with the metal base material and becomes a protective rust preventive film that does not peel semipermanently. It is better to apply a Raydent (registered trademark) process.

Hereinafter, an example will be described based on the drawings.
FIG. 1 is a view showing a state in which a ballpoint pen tip is inserted into the holder member H.
The mortar-shaped inclined hole Ha of the holder member H has a large-diameter opening Hb on the side where the ball-point pen tip 1 is inserted, and is formed with a larger diameter than the rear-side large-diameter portion 2 of the ball-point pen tip 1. The inner diameter of the small-diameter opening Hc, which is opposite to the large-diameter opening Hb, is formed so as to be located behind the processing depth of the radial groove 3 that is the ink flow path of the ball-point pen tip 1.
Behind the large-diameter opening Hb of the holder member H is a guide member G having a diameter of about 0.1 mm from the rear large-diameter portion 2 of the ballpoint pen tip 1 and the axis of the mortar-shaped inclined hole Ha of the holder member H. The ballpoint pen tip 1 is vertically supported and fixed together with the mortar-shaped inclined hole Ha of the holder member H.

An example of the ball-point pen tip manufactured in FIG. 2 and FIG. 3 is shown.
The example shown in FIG. 2 is an example of what is called a so-called bullet-type chip. Inside the ball-point pen tip 1, there is disposed a coil spring 4 in which a rod-like portion 4b is integrally formed on the tip side of the coil portion 4a. A thin portion 5 is formed at the rear end of the ballpoint pen tip 1 to apply a caulking for rearward regulation of the coil spring 4.
The external shape of the ballpoint pen tip 1 is such that an inclined surface 7 connecting the rear large diameter portion 2 and the front small diameter portion 6 is processed with a cutting blade formed at 15 ° with respect to the axial center. The opening angle is measured from 14.9 ° to 15.1 ° and an average of 15.02 °.

FIG. 3 shows an example of a ball-point pen tip having an outer shape of a type different from that described above. This is an example of what is called a needle-type tip.
A small-diameter cylindrical portion 8 is provided at the tip on the ball side to improve visibility, and the opening angle of the inclined surface 7 of the ballpoint pen tip 1 is measured from 14.9 ° to 15.1 °, an average of 15.02 °. A small-diameter cylindrical portion 8 is formed in the post-process of the above-described bullet-type ball-point pen tip.
A coil spring 4 is disposed inside the ballpoint pen tip 1. A thin portion 5 is formed at the rear end of the ballpoint pen tip 1 to apply a caulking for rearward regulation of the coil spring 4.

FIG. 4 shows an example of processing accompanied by a pressing force from the back of the ballpoint pen tip. In order to restrict the rearward movement of the coil spring for biasing the ball forward, the rear end portion of the ballpoint pen tip 1 is crimped to reduce its diameter and the coil spring is fixed.
In combination with the mortar-shaped inclined hole Ha of the holder member H and the shaft center of the guide member G, a ceramic caulking jig K having slipperiness and hardness and excellent durability is installed, and the caulking jig K is lowered. The tip inclined portion Pa of the cemented carbide pin P installed at the center of the crimping jig K abuts on the inner diameter of the coil spring 4 and pushes the coil spring 4 into the ballpoint pen tip 1, and then the inner surface of the crimping jig K The inclined portion Ka presses the thin portion 5 of the ball-point pen chip 1, and the thin portion 5 is reduced in diameter.
At this time, since the ball-point pen tip 1 is fixedly held by the mortar-shaped inclined hole Ha of the holder member H and the guide member G, the ball-point pen tip 1 fluctuates, and the tip of the pin P installed on the crimping jig K is connected to the coil spring 4. The coil spring 4 cannot be pushed down into the interior of the ballpoint pen tip 1, and the coil spring 4 is crimped in a state where it protrudes from the rear end of the ballpoint pen tip 1 to prevent the pressure load on the ball from decreasing. Yes.
In particular, in a machine that processes with an index table, when the table rotates and moves to the next process, the ball-point pen tip 1 tends to fluctuate due to centrifugal force, and it is important to fix and hold the ball-point pen tip 1.

The inner wall opening angle of the mortar-shaped inclined hole Ha of the holder member H is made different, and 100 pieces of the above-described thinning portion 5 of the ball-point pen tip 1 are swaged, and the biting, the inclined surface 7 and the rear large diameter portion 2 are performed. Check the blur at the point of intersection. However, the opening angle of the inner wall of the mortar-shaped inclined hole Ha of the holder member H is the inclined angle of the discharge master that processes the inclined hole Ha.
The test results are listed in (Table 1).

In Example 4 in which the inner wall opening angle of the mortar-shaped inclined hole of the holder member with respect to the inclined surface angle connecting the rear-side large-diameter portion and the front-side small-diameter portion of the ball-point pen tip is acute, there is no occurrence of biting. Since the difference in the opening angle of the inner wall of the holder member with respect to the inclined surface angle is as large as about 5 °, the intersection of the inclined surface of the ball-point pen tip and the rear large-diameter portion slid around the circumference.
Examples 1 to 3 in which the inner wall opening angle of the holder member with respect to the inclined surface angle of the ballpoint pen tip is an acute angle and the difference is 0.5 ° to 1 ° have no biting on the holder member, and no scratch is generated. There is no occurrence of slippage at the intersection between the inclined surface and the rear large diameter portion, which is better.
On the other hand, in Comparative Examples 1 and 2, since the inner wall opening angle of the holder member with respect to the inclined surface angle of the ballpoint pen tip is an obtuse angle, it bites into the small-diameter opening of the holder member and a burr is generated.
In Comparative Example 2 in which the difference in the opening angle of the inner wall of the holder member with respect to the inclined surface angle of the ball-point pen tip is substantially 0 °, the inner wall opening of the holder member with respect to the inclined surface angle of the ball-point pen tip is due to the variation in the inclined surface angle of the ball-point pen tip. As the angle became acute or obtuse, biting occurred with the ballpoint pen tip.

DESCRIPTION OF SYMBOLS 1 Ball-point pen tip 2 Rear side large diameter part 3 Radial groove 4 Coil spring 4a Coil part 4b Bar-shaped part 5 Thin part 6 Front side small diameter part 7 Inclined surface 8 Small diameter cylindrical part H Holder member Ha Inclined hole Hb Large diameter opening part Hc Small diameter opening Part G Guide member K Caulking jig Ka Inside inclined part P Pin Pa Tip inclined part

Claims (1)

In a ballpoint pen tip manufacturing method, in which a ballpoint pen tip having a front side small diameter portion and a rear side large diameter portion is processed with a pressing force from the rear, a mortar of a holder member in which the ballpoint pen tip is arranged and held during processing The opening angle of the inner wall of the slanted hole is sharper than the slanting angle of the line connecting the small diameter part and the large diameter part of the outer shape of the ballpoint pen tip, and the inner diameter of the large diameter opening of the mortar-shaped slanted hole of the holder member is Method for manufacturing ball-point pen tip having larger diameter than rear-side large-diameter portion of ball-point pen tip

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