JP2517444Y2 - Writing instrument tail plug - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) Ultrasonic welding secures to the cylindrical rear end of the ink container body, such as a shaft cylinder that contains an ink absorber or an ink tank that stores ink in a raw ink state. The present invention relates to a synthetic resin tail plug of a writing instrument such as a fiber pen, a resin pen, a small tube type writing instrument, a ballpoint pen, a fountain pen, a valve structure modifying instrument, an eyeliner, a lip color and the like.

(Prior Art) It has become extremely common to fix a synthetic resin tail plug to the rear end of an ink container. As mentioned above, the rear end of the barrel, which is generally called batting, is made to be impregnated with ink and the ink absorber is built in.
There are tail plugs at the rear end of various ink containers, such as the rear end of a typical fountain pen replaceable ink tank, and also the rear end of a cartridge with a pen tip of a pen tip retractable writing instrument. It is fixed.

It is required that the tail plug is firmly fixed to the ink container. Insufficient fixation may cause ink leakage. In some cases, an air exchange path is secured, but even in such a case, the fixing itself must be surely performed for reasons such as prevention of falling.

A typical example of reliable fixation is to provide some annular projections on the outer wall surface of the tail plug that is inserted into the cylindrical rear end of the ink container, and to press the annular press-fitting part between the ink container and the inner wall surface. Are press-fitted so that they are formed at a plurality of locations. There is also a method of using an adhesive, and another method is ultrasonic welding according to the present invention.

(Problems to be solved by the invention) When the tail end is fixed to the rear end of the ink container by ultrasonic welding, a fixing defect may occur during mass production. An object of the present invention is to suppress the occurrence of this problem and to improve productivity.

(Means for Solving the Problems) A synthetic resin tail plug of a writing instrument fixed to a cylindrical rear end portion of an ink container main body by ultrasonic welding, the tip cylindrical portion being inserted into an inner wall portion of the main body. And a flange portion that abuts on the rear end of the main body, forms an annular welding protrusion on the front side surface of the collar portion, and abuts the inner wall portion of the main body on the outer wall of the tip tubular portion. The above problem can be solved by using a tail plug of a writing instrument that is formed by forming a plurality of protrusions radially so that the contact positions with the inner wall are on the same circumference.

(Example) An example is shown in attached FIG. 1 to FIG.

Reference numeral 1 is a shaft cylinder, and a tip holder 3 projecting a pen tip 2 is appropriately fixed to the tip thereof, and an ink occlusion body 4 in which a rear end of the pen tip 2 is embedded is incorporated. That is,
This example is an example of a writing instrument with a built-in ink occlusion body. A tail plug 6 is fixed to a tubular rear end portion 5 of the shaft cylinder 1. FIG. 2 shows the state before ultrasonic welding and FIG. 3 shows the state after ultrasonic welding.
As shown in the figure, the tail plug 6 has a front tube portion 8 that is inserted into the inner wall portion 7 of the shaft cylinder 1, and a flange portion 9 that abuts on the rear end of the shaft cylinder 1. An annular welding protrusion 11 is formed on the front side surface 10 of the, and after welding, as shown in FIG.
Is melted and the front side surface 10 of the collar portion 9 abuts and is fixed to the rear end of the barrel 1. Incidentally, here, the front side surface 10 of the collar portion 9 has a step between the inner portion 10a and the outer portion 10b with the welding protrusion 11 in between, but such a step is provided. This is preferable because it is possible to prevent the welding protrusion 11 from melting and protruding to the outside.

Further, a projection 12 is formed on the outer wall 8a of the tip cylindrical portion 8 of the tail plug 6. This protrusion 12 is not annular. When it is annular, when the tail plug 6 is fixed to the tubular rear end portion 5 of the barrel 1, the resistance when inserting the front tubular portion 8 into the inner wall portion 7 becomes large. As the ultrasonic welding progresses, the tip tube portion 8 will cause defective welding unless the amount of insertion into the inner wall portion 7 is smoothly increased in response to the contact of the horn. As shown in one shape example in FIGS. 4 to 7, the projection 12 imparts the cross-section irregularity to the front tube portion 8 and reduces the contact area of the front tube portion 8 with the inner wall portion 7 in the cross section. However, it is necessary to eliminate rattling of the tail plug 6 with respect to the inner wall portion 7 of the shaft cylinder 1 and to suppress the outward deformation of the shaft cylinder 1 as much as possible. In addition, FIG. 4 is a partial sphere, FIG. 5 is a semi-cylindrical shape, and FIG.
The figure shows a continuous shape, and FIG. 7 shows a quadrangular pyramid shape, but if a plurality of radial pyramids are formed, the number, arrangement state, shape, etc. can be adjusted appropriately. It can also be raised.

In addition to the above, various modifications can be made. For example, the tail plug 6
As the above, the one in which the two recessed portions 14 are formed on the rear side surface 13 of the collar portion 9 is shown. By arranging a gate portion for injection molding (indicated by a dotted projection at the center of the bottom of the concave portion 14) at the back of the concave portion 14, the horn abuts the rear side surface 13 of the collar portion 9. Is uniform in a ring shape, which is preferable in the case of an injection molded product of a synthetic resin such as polyethylene, polypropylene, nylon, or polyacetal. Further, forming the recessed portions 14 in two or more steps is convenient for sticking a seal such as a color display at the step portion on the opening side (right side in the drawing) of the recessed portions 14. Since it can be used in combination with what has been described above, an example of such a thing is shown in FIGS. 8 to 10. Further, the shaft cylinder having the built-in ink absorber as the ink container is shown, but it may be a replaceable ink tank such as a fountain pen, a cartridge of a retractable writing instrument, etc. The ink tank may also serve as the ink tank to be housed.

(Effect of the Invention) A tail plug of a writing instrument made of a synthetic resin, which is fixed to a cylindrical rear end portion of an ink container body by ultrasonic welding, a tip cylinder portion to be inserted into an inner wall portion of the body, and the body body. A flange portion that abuts on a rear end of the collar portion, and an annular welding protrusion is formed on a front side surface of the collar portion, and a protrusion that abuts an inner wall portion of the main body is radially formed on an outer wall of the front tubular portion. Since it is a multi-purpose writing instrument tail plug, it is possible to suppress the occurrence of sticking defects during mass production when fixing to the tail plug at the rear end of the ink container by ultrasonic welding. obtain.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the present invention, FIG. 2 is a sectional view showing a state before ultrasonic welding of the tail plug of FIG. 1, and FIG.
Sectional drawing which shows the state after ultrasonic welding of the tail plug of the figure, FIG.
FIG. 7 is a side view showing an example of the shape of the tail plug, and FIGS. 8 to 10 are sectional views showing modified examples of the tail plug. 1 ... Shaft cylinder, 2 ... Pen tip, 3 ... Chip holder, 4
…… Ink absorber, 5 …… Cylindrical rear end, 6 …… Tail plug, 7
…… Inner wall part, 8 …… Tip cylinder part, 8a …… Outside wall, 9 …… Brim part, 10 …… Front side surface, 10a …… Inner part, 10b …… Outside part, 11 …… Welding ridge, 12 …… Protrusions, 13 …… Rear side, 14…
… A recess.

Claims (1)

(57) [Scope of utility model registration request] 1. A tail plug made of synthetic resin for a writing instrument, which is fixed to a cylindrical rear end portion of an ink container body by ultrasonic welding.
The front cylinder part has a front cylinder part to be inserted into the inner wall part of the main body, and a flange part that comes into contact with the rear end of the main body, and forms an annular welding protrusion on the front side surface of the flange part. A tail plug of a writing instrument, in which a plurality of projections that come into contact with the inner wall portion of the main body are radially formed on the outer wall of the main body so that the contact positions with the inner wall portion are on the same circumference.