JP4893418B2 - Ballpoint pen manufacturing method - Google Patents

Description

  In the present invention, a coil spring is inserted from a rear end opening of a ball holder that rotatably holds a part of a ball serving as an ink application member from a front end opening of an ink through hole. By crimping the rear end opening to a smaller diameter than the caulking contact portion of the coil spring, the coil spring is urged with its tip abutting directly on the ball or through another member to exert elastic force. The present invention relates to a method of manufacturing a ballpoint pen tip that is installed in an accumulated state.

A ball-point pen tip that prevents the ink from drying and leaking when not in use by installing a coil spring inside the ball holder, pressing the ball with the resilience, and pressing the ball against the inner wall of the tip opening (see Patent Document 1) )It has been known.
Japanese Patent Laid-Open No. 08-142571

  In the device described in Patent Document 1, the coil spring inserted into the ball holder becomes an obstacle when the diameter of the ball holder is reduced by caulking the rear end. If the rear end position of the coil spring is the same before and after the caulking, the resilience of the coil spring will not be exerted, and even if the coil spring is pushed inward with a jig etc., the outer diameter of the coil spring It was pushed with a jig having a diameter of, and in the end, the jig became a hindrance during caulking, and workability was poor.

  In the present invention, a coil spring is inserted from a rear end opening of a ball holder that rotatably holds a part of a ball serving as an ink application member from a front end opening of an ink through hole. By crimping the rear end opening to a smaller diameter than the caulking contact portion of the coil spring, the coil spring is urged with its tip abutting directly on the ball or through another member to exert elastic force. In the manufacturing method of the ballpoint pen tip to be installed in an accumulated state, a pressing portion having a smaller diameter than the caulking contact portion is formed at the rear end of the coil spring, and the pressing portion is crimped at the rear end of the ball holder. After pressing the rear end of the ball holder with a pressing jig having a pressing end smaller than the opening diameter of the ball holder, processing to the predetermined inner diameter, The method of manufacturing a ball-point pen tip to release the hold down spring and gist.

  Since the rear end of the coil spring is pressed, the coil spring can be pushed in with a jig whose diameter is smaller than the inner diameter of the caulking contact part, and neither the coil spring nor the jig interferes with caulking. Can be manufactured.

The ball-point pen tip manufactured by this invention installs the coil spring which urges | biases a ball | bowl forward directly or via another member in the ball holder which holds a ball | bowl rotatably.
Such a ball-point pen tip is connected to an ink tank directly or via a relay member to communicate ink. Even a type of ballpoint pen that uses an ink tank as an exterior member may be referred to as a so-called refill, and may include an exterior body as another member. In addition, a cap that fits the pen tip may be provided as a separate member, or a writing instrument in which the pen tip appears and disappears by an operation such as a rear end knock without providing a cap may be used. The ball-point pen can be said to be preferable because the front is urged forward and brought into contact with the inner edge of the opening of the ball holder.

  The ball can be made of cemented carbide mainly composed of tungsten carbide, titanium, cobalt, chromium, nickel, etc., or ceramic such as silicon carbide, silicon nitride, titanium nitride, alumina, zirconia, etc. The surface texture is adjusted according to the ink or writing conditions by processing. A ball diameter of about 0.1 mm to 2.0 mm is used.

  As the ball holder, stainless steel, white or brass, or brass can be used as a material, and a workpiece obtained by shearing from a coil material to an appropriate length is used as a workpiece. In order to place importance on workability, it is desirable to have a high machinability and a high plastic deformability.

As the coil spring, stainless steel wire for spring, piano wire, hard steel wire, phosphor bronze wire, etc. can be used as the material, and the wire diameter is preferably 0.08 mm to 0.20 mm. The tip of the coil spring that is in contact with the ball must pass through a narrow passage to reach the ball, so it can be a small-diameter winding, or it can stand up straight without winding a wire, Other members can be connected.
The rear end of the coil spring is a pushing portion having a smaller diameter than the coil portion. Adjacent wires such as end turn portions may be in close contact with the small-diameter pushing portion from the coil portion.

  As the ink to be used, either water-based ink or oil-based ink can be used. A mixture of either a dye or a pigment or a mixture of both can be used, and it may be a gel added with a viscosity at the time of standing. A so-called raw ink in which the ink occluded and held in an ink occlusion body such as a fiber bundling body is arranged in the ink storage part, or a free ink is directly filled in a container without using such an ink occlusion body It can be used for an ink jet type or a pressure type that supports a discharge by pressing the back of the ink with compressed air or the like. .

  In addition, the ballpoint pen tip manufactured by the present invention urges the ball forward by a coil spring and tries to make it liquid-tight and air-tight in the circumferential contact with the ball holder. It is more effective for ballpoint pens that support internal pressure type or structure that applies pressure by pressing the container, and ballpoint pens that use ink containing volatile components and dislike that the ink in the ballpoint pen touches the outside air. It can be said that it is something to demonstrate.

In the ballpoint pen tip manufacturing method of the present invention, a coil spring is inserted from the rear end opening of the ballpoint pen tip, the coil spring is compressed by a pressing jig, and the crimping contact portion is accommodated in the ballpoint pen tip. A caulking process that reduces the diameter of the rear end opening is performed to prevent the coil spring from coming out of the ballpoint pen tip.
The pressing jig can contact the small-diameter pressing portion of the coil spring, and at least the portion to be inserted into the ball holder needs to have a smaller diameter than the reduced inner diameter of the crimping portion after the crimping process. . The portion that directly contacts the coil spring is a portion having a circumscribed circle diameter larger than the inscribed circle diameter of the small-diameter push portion of the coil spring. When the coil spring is compressed, the contact between the push jig and the coil spring It is necessary to prevent contact. The tip of the pushing jig can be made smaller in diameter than the inner diameter of the rear end hole of the coil spring, and when pushed, it can be inserted into the rear end hole of the coil spring and guided in the center. At this time, if the portion reaching the tip of the pushing jig is inclined or gently curved, the center guide is smooth without being caught. However, if the jig and the coil spring are in a press-fitting relationship and become fixed, there is a risk of becoming an obstacle when the spring and the jig are separated after completion of processing, and should be avoided.

FIG. 1 is a longitudinal sectional view showing an example of a ball-point pen tip manufactured by the manufacturing method of the present invention. Moreover, the enlarged view of the I part of FIG. 1 is shown in FIG. 2, and the enlarged view of the II part is shown in FIG.
A ball 1 serving as an application member is installed at the tip of the ball holder 2, and the tip opening 2a from which the ball 1 is exposed is slightly smaller than the outer diameter of the ball 1 to prevent the ball from falling off. Is formed. Further, the ball holder 2 has a through hole as an ink passage, and an inward projecting portion 2b is formed in the through hole to restrict the backward movement of the ball 1. The through hole is a ball holding chamber 2c as a range in which the ball 1 can move back and forth between the tip opening 2a and the inward projecting portion 2b, and the inner projecting portion 2b is formed in a small-diameter inner hole 2d. The rear portion of the inward protruding portion 2b is a rear hole 2e.

  In the inward projecting portion 2b, a plurality of grooves 2f through which ink can flow is opened to the inner hole 2d and the ball holding chamber 2c. This groove 2f does not communicate with the rear hole 2e, but this is to suppress the ink that has reached the ball holding chamber 2c from flowing back as much as possible. When it is desired to increase the discharge amount, the groove 2f may be formed to penetrate to the rear hole 2e.

  A concave transfer surface 2p to which the surface state of the ball 1 is transferred by pressing the ball 1 is formed on the tip side of the inward protruding portion 2b. The surface of the ball 1 has an arithmetic average height Ra (JIS B 0601: 2001) of the contour curve of about 0.002 μm or more and 0.030 μm or less, and the Ra of the transfer surface 2p is 1 μm or less. The transfer surface 2p is divided in the circumferential direction by a groove 2f.

A tip end portion of the outer shape of the ball holder 2 is subjected to plastic deformation by rolling to form a tip tapered portion 2h having a diameter reduced toward the tip. Due to this diameter reduction processing, the inner edge of the tip opening 2a is also reduced in diameter to prevent the ball 1 from falling off.
The opening angle of the tip tapered portion 2h is 50 to 90 degrees, and has a tapered shape with a larger opening angle than the rear tapered portion 2i that is 15 to 45 degrees. Here, the “opening angle” is an angle formed by the inclined surfaces facing each other when a longitudinal section in a plane passing through the center is viewed.
This rolling process is performed by pressing a rotatable roller (not shown). The surface of the roller that contacts the member to be processed is a mirror surface with almost no fine irregularities, and the surface state of the roller is transferred to the ball holder 2. If the surface of the tip tapered portion 2h of the ball holder 2 is in a mirror state where the arithmetic average height Ra (JIS B 0601: 2001) of the contour curve is 1 μm or less, Reduces frictional resistance.

A coil spring 3 is disposed inside the ball holder 2. One end of the coil spring 3 forms a straight portion 3b extending from a substantially central position of the coil portion 3a, and the tip of the coil spring 3 abuts against the ball 1 and urges forward, whereby the tip opening 2a of the ball holder 2 is The ball 1 is in contact with the inner edge 2j. Since the inner edge 2j is required to be in contact with the ball 1 without a gap, the cross-sectional shape is circular, and when the above-described tapered end portion 2h is formed in order to increase the contact and improve the sealing performance The inner edge 2j is formed as a belt-like portion having a width substantially the same curvature as the ball by being pressed against the ball 1 and plastically deformed by the rolling process.
As shown in FIG. 3, at the other end of the coil spring 3, a small-diameter pushing portion 3c having an inscribed circle diameter smaller than the outer diameter of the coil portion 3a is formed.

A manufacturing method for installing the coil spring 3 in the ball holder 2 will be described.
FIG. 4 is a longitudinal sectional view of the main part showing the step of inserting the coil spring 3, and the coil spring 3 is inserted with the rear end opening 2k of the ball holder 2 facing upward and the small-diameter pushing portion 3c facing upward. It is a thing. In this state, the straight portion 3 b of the coil spring 3 passes through the inner hole 2 d and the tip thereof is in contact with the ball 1.

  At the rear part of the ball holder 2, a caulking recess 2r is formed as a thin part. When deforming by caulking, it can be deformed with less force than applying deformation to other parts, and by adjusting the magnitude of the force, the inflection point of plastic deformation can be determined without deforming other parts as much as possible. It can be in the recess 2r.

FIG. 5 is a longitudinal sectional view of an essential part showing a process of compressing the coil spring 3.
The pushing jig 4 has a small diameter portion 4a inserted into the coil spring 3 at the tip. The outer diameter of the small-diameter portion 4a of the pressing jig 4 is smaller than the inscribed circle diameter of the small-diameter pressing portion 3c of the coil spring 3, and the large-diameter portion 4b of the pressing jig 4 is larger in diameter than the small-diameter portion 4a. However, the diameter is smaller than the inner diameter of the caulking contact portion 3d. Thus, in order to prevent the coil spring 3 from coming off by caulking, the inscribed circle diameter after reducing the rear end opening 2k of the ball holder 2 is made smaller than the outer diameter of the caulking contact part 3d. Although necessary, the large-diameter portion 4b of the pressing jig 4 is not lost after the crimping process.

  The small-diameter portion 4a and the large-diameter portion 4b are connected by a connecting step portion 4c that is an inclined surface, but may be a surface perpendicular to the axis of the pushing jig 4 without being an inclined surface. Further, the small diameter part 4a, the large diameter part 4b, and the connection step part 4c may be curved.

FIG. 6 is a vertical cross-sectional view of the main part showing a step of reducing the diameter by caulking the rear end portion of the ball holder 2.
The crimping tool 5 is fixed to the pushing jig 4 and operates so that each does not shift from the center of the rear end opening 2k of the ball holder 2.
The caulking taper portion 5a installed in the caulking tool 5 has a tapered shape in which the inner diameter gradually decreases toward the rear. Before the crimping tool 5 comes into contact with the ball holder 2, the pushing jig 4 pushes and shrinks the coil spring 3, and the crimping contact portion 3d is crimped to the reduced diameter portion inner wall 2n. To position. Next, the caulking taper portion 5a is brought into contact with the ball holder 2 and the pushing jig 4 and the caulking processing tool 5 are simultaneously moved forward, thereby deforming the caulking concave portion 2r of the ball holder 2 and the caulking taper portion 5a. A caulking process that plastically deforms so as to have substantially the same tapered shape is performed. In order to minimize the compression of the coil spring 3, the pushing jig 4 is inserted into the ball holder 2, the coil spring 3 is fixed in a compressed state, and the crimping tool 5 is fixed to the pushing jig 4. May be advanced relatively.

  Thereafter, the crimping tool 5 is retracted so as to be separated from the ball holder 2, and the pushing jig 4 is also retracted while gradually releasing the compression of the coil spring 3. The caulking contact portion 3d, which is the substantially rear end portion of the coil portion 3a of the coil spring 3, is brought into contact with the inner wall 2n of the reduced diameter portion of the ball holder 2, so that the coil spring 3 and the pressing jig 4 are separated from each other. Is installed in such a manner that it cannot be removed from the ball holder 2 and urges the ball forward.

FIG. 7 shows another example. An example corresponding to FIG. 6 in the above example is shown.
A caulking roller 6 is used instead of the caulking processing tool 5. The caulking roller 6 can be moved up and down without being fixed to the pushing jig 4, and the lower end of the ball holder 2 is sandwiched in the position where the roller 6 a capable of rotation is opposed to the lower end. A caulking taper surface 6b is formed on the roller 6a. The caulking roller 6 is rotated and pressed against the rear end opening 2k of the ball holder 2, and the vicinity of the portion is plastically deformed inward with some springback. By this caulking process, the coil spring 3 is prevented from coming off from the ball holder 2.
As a result, it is possible to perform caulking with higher accuracy of centrality and diameter.

  A ballpoint pen tip with a built-in coil spring that urges the ball forward and closes the tip opening to seal it, preventing ink drying and leakage. This is a manufacturing method for preventing slipping.

The longitudinal cross-sectional view which shows an example of the ball-point pen tip manufactured by the manufacturing method of this invention Part I enlarged view of FIG. Part II enlarged view of FIG. Main part enlarged vertical sectional view showing the manufacturing process Main part longitudinal cross-sectional view which shows the process of compressing the coil spring 3 Principal longitudinal sectional view showing a step of reducing the diameter by caulking the rear end of the ball holder 3 Principal longitudinal sectional view showing another embodiment

Explanation of symbols

1 Ball 2 Ball holder 2a Front opening 2b Inward projecting portion 2c Ball holding chamber 2d Small diameter portion 2e Rear hole 2f Groove 2p Transfer surface 2h Front taper portion 2i Rear taper portion 2j Inner edge 2k Rear end opening portion 2r Caulking recess 2n Shrinkage Diameter inner wall 3 Coil spring 3a Coil part 3b Straight line part 3c Small diameter pushing part 3d Caulking contact part 4 Pushing jig 4a Small diameter part 4b Large diameter part 4c Connection step part 5 Caulking tool 5a Caulking taper part 6 Caulking roller 6a Roller 6b Caulking taper surface

Claims (1)

Insert a coil spring from the rear end opening of the ball holder that holds the part of the ball that becomes the ink application member rotatably from the front opening of the ink passage hole, and then opens the rear end of the ball holder. The coil spring is squeezed to have a smaller diameter than the crimping contact portion of the coil spring, and the coil spring is urged with its tip abutting directly or via another member while accumulating elastic force. In the manufacturing method of the ballpoint pen tip to be installed, a pressing portion having a smaller diameter than the caulking contact portion is formed at the rear end of the coil spring, and the pressing portion is formed from the opening diameter after the caulking process at the rear end of the ball holder. After pressing the back end of the ball holder with a pressing jig having a small-diameter pressing end, and processing to a predetermined caulking inner diameter, the coil spring of the pressing jig Ballpoint pen tip manufacturing method of releasing the state in which the press.