JPH0228070Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a sharpening pencil using a ball chuck.

A ball chuck has the characteristic that it is possible to pull out the lead with a weak force of only a few grams, and has sufficient force to hold the lead in place against writing pressure, so a holding chuck that is movable in the axial direction is used. In view of this, various types of sharp pencils have been developed, such as a pipe slide type, a tip notch type, and a finger-feeding type, which allow the lead to be drawn out while being held without the need for a notch at the rear end. However, even with these sharp pencils, when one lead is used up, in order to draw out the next lead, it is necessary to operate the notch at the rear end in the same way as with conventional flickers. The mechanism and operating state of the sharpening pencil will be explained in detail using the conventional finger-feeding type sharpening pencil shown in FIG. 1 as an example.

The chuck case 1 has a ball chuck (core fixed chuck 3) in the retracted state by a chuck spring 2.
and ball 4. ) is installed inside the chuck case 1, and on the outer periphery of the rear end of the chuck case 1, a core case 6 having a slidable friction fitting part 5 is attached to a knob spring 7.
It is pressed rearward by the stopper 8 and is fitted into the stopper 8 in a state where it is pressed against the stopper 8. A holding chuck 11 is installed inside the shaft joint 9 installed in front of the ball chuck and is fixed to a slider 10 protruding from the outer surface and interlocks in the axial direction. Holding chuck 11
The core is drawn out from the ball chuck by means of the ball chuck. When the lead held by the holding chuck 11 is used up, in order to feed out the next lead, a knock rod (not shown) integrally connected to the rear of the lead case 6 is operated to fix the lead. A series of operations in which the next lead is fed out a certain amount using chuck 3, then the chuck is released, the next lead falls under its own weight and touches the remaining lead, the chuck is returned to its original position, the lead is fixed again, and the lead is fed out a certain amount. It is necessary to remove the remaining core by doing this. In this case, when the lead fixing chuck 3 is open, it needs to be sufficiently opened to allow the lead to fall due to its own weight.
When the rear end is notched, first the core case 6 and the chuck case 1 move forward together with the ball chuck without sliding due to their frictional force, and the retaining ring 12 fitted to the tip of the chuck case 1 moves against the inner wall 13 of the shaft coupling 9. When the lead case 6 collides with the lead fixing chuck 3, the lead case 6 slides its friction fitting part 5 and moves forward independently, and its inner step part 14 abuts against the rear end of the lead fixing chuck 3, causing the lead fixing chuck 3 to move forward. The structure is such that the opening is sufficiently opened. When the ball chuck, chuck case 1 and core case 6 are returned to their original positions by the knock spring 7 by releasing the knock pressure from the open state of the core fixing chuck 3, the chuck case 1 has its outer surface step 15 pressed against the inner surface step 17 of the shaft cylinder 16. Although the core case 6 can be returned to a predetermined position by impact, a stopper 8 must be provided separately for the core case 6, and the lead case 6 must be returned to a predetermined position by being stopped by the stopper 8. Since the stopper 8 is constructed by a biaxial structure or by fixing separate parts, the structure and assembly are complicated, which is a major hindrance to the manufacture of inexpensive sharpening pencils. There is a method of eliminating this stopper 8 and adjusting the balance between the frictional force of the frictional fitting part 5 of the core case 6 and the spring force of the knob spring 7, but this makes manufacturing more difficult and the frictional force changes due to wear. Difficult problems arise.

The first purpose of this invention is to provide a sharp pencil that can be manufactured at low cost by eliminating the stopper of the lead case and simplifying the structure and assembly, without impairing the conventional functions. A second purpose is to facilitate the disassembly of the chuck case and core case, which are constructed along the same lines, to facilitate the exchange of the chuck set.

The present invention has a ball chuck that is slidably friction-fitted to the rear end of a chuck case that is configured to be blocked by the inner step of the shaft cylinder and prevented from moving backward, and is pressed rearward by a locking spring. The first feature is that a step is provided at the rear end of the friction-fitting part of the lead case to the chuck case, and a step is provided on the chuck case that abuts this step. The first feature is that the shaft cylinder is provided with a tapered surface that contacts this tapered surface to expand the inner diameter of the front end of the core case and release the abutment between the stepped portion of the chuck case and the stepped portion of the core case. The above object is achieved by the following features.

The embodiment of the present invention shown in FIG. 2 will be described below. The figure shows a touch-feeding mechanical pencil. A chuck case 22 has a core fixing chuck 20 with a ball 18 fitted into an outer recess 19 retracted by a chuck spring 21, and has a protruding step 23 formed on the outer surface of the chuck case 23 at a substantially central portion thereof. small diameter groove 2
4 is formed, and the rear end edge of the groove portion 24 is a stepped portion 25. On the other hand, the core case 26 has a small inner diameter part 27 with a large peripheral wall thickness at its front end, and a large inner diameter part 28 with a small wall thickness behind it, and a step part 29 is provided at the boundary thereof. . The core case 26 has an axial slit (omitted in the drawing), and is fitted from the rear end of the chuck case 22, and has a small inner diameter portion 27.
is fitted into the groove 24 of the chuck case 22, and their inner surfaces are brought into contact with each other with the required frictional force, resulting in a friction fit. On the other hand, a knock spring 33 is interposed between the outer surface stepped portion 30 of the core case 26 and the rear surface of the inner surface stepped portion 32 of the shaft tube 31 to press the core case 26 rearward. Therefore, the small inner diameter portion 27 of the core case 26, that is, the step portion 29 at the rear end of the friction fit portion abuts against the step portion 25 of the groove portion 24 of the chuck case 22, and the step portion 23 on the outer surface of the chuck case 22 also contacts the shaft tube 31. It is brought into contact with the front surface of the inner surface stepped portion 32 of. The stepped portions 29 and 25 of the lead case and the chuck case are positioned so that the stepped portions abut each other and the rear end of the lead fixing chuck 20 does not come into contact with the inner surface stepped portion 34 of the lead case 26. . The operation status of the core case 26, chuck case 22, and ball chuck by operating the rear end knob, and the holding chuck 35 and slider 36 installed in front of the ball chuck.
The operating conditions are the same as those of the conventional example described above. Next, a tapered surface 37 is formed on the front end surface of the friction fitting portion, that is, the small inner diameter portion 27 of the core case 26, and a tapered surface 38 is similarly formed on the protrusion provided on the rear surface of the inner stepped portion 32 of the shaft tube 31. is formed, and when the core case 26 is pushed forward by sliding its friction fitting portion, the tapered surfaces 37 and 38 come into contact with each other, and the core case 26
The inner diameter of the front end is expanded by a slit, and the abutment between the step 29 of the lead case and the step 25 of the chuck case is released, allowing the chuck case 22 to be removed from the lead case 26.

The present invention is constructed as described above, and the retracted position of the lead case can be kept at a predetermined position by the stepped part at the rear end of the friction fitting part of the lead case and the stepped part of the chuck case, and a stopper is not required. As a result, it is possible to provide an inexpensive sharpening pencil whose structure and assembly are simplified and whose functions are not impaired in any way compared to conventional examples. In addition, by providing a tapered surface at the front end of the core case and a tapered surface on the inner stepped part of the shaft cylinder, it is possible to remove the chuck case from the core case, which facilitates its disassembly and makes replacing the chuck set much more convenient. be. At this time, it is preferable that the chuck case be allowed to be pulled out from the core case only when the cap is removed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional mechanical pencil that can be fed out with a finger, and FIG. 2 is a vertical cross-sectional view of a mechanical pencil that can be fed out with a finger according to an embodiment of the present invention. 1...Chuck case, 2...Chuck spring,
3... Core fixing chuck, 4... Ball, 5... Friction fitting part, 6... Core case, 7... Knock spring, 8... Stopper, 9... Shaft coupling, 10...
...Slider, 11...Holding chuck, 12...
Retaining ring, 13... Inner wall of shaft joint, 14... Inner surface step, 15... Outer step, 16... Shaft cylinder, 17
... Inner surface step, 18 ... Ball, 19 ... Outer surface recess, 20 ... Core fixing chuck, 21 ... Chuck spring, 22 ... Chuck case, 23 ... Step,
24...Groove, 25...Step, 26...Core case, 27...Small inner diameter section, 28...Large inner diameter section, 29
... Stepped portion, 30 ... Outer step section, 31 ... Shaft cylinder, 3
2...Inner step, 33...Knot spring, 3
4... Inner stepped portion, 35... Holding chuck, 36...
...slider, 37...tapered surface, 38...tapered surface.

Claims (1)

[Scope of utility model registration request] A core that is slidably friction-fitted to the rear end of a chuck case that has a ball chuck inside and is configured to be blocked by the inner step of the shaft cylinder and prevented from retreating, and is pressed rearward by a locking spring. A stepped portion is provided at the rear end of the friction-fitting portion of the case to the chuck case, and a stepped portion is provided on the chuck case that abuts this stepped portion, and a tapered surface is provided on the front end surface of the core case, and the tapered surface is in contact with the chuck case. A sharp pencil characterized in that the barrel is provided with a tapered surface that enlarges the inner diameter of the front end of the lead case and releases the abutment between the stepped part of the chuck case and the stepped part of the lead case.