JPH0228073Y2 - - Google Patents

Description

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

As is well-known, ball chucks allow you to pull out the lead with a weak force of only a few grams, and have sufficient force to hold the lead against writing pressure, so they are used in pencils such as the tactile-feeding type sharp pencil shown in Figure 1. It is widely used in Similar to a normal notch-type mechanical pencil, there is a risk that the lead of such a pencil may break when writing if the lead is pushed out too much or if high pressure is applied. In order to correct an overextended lead to an appropriate length, for example, with the conventional finger-feeding type sharpening pencil shown in FIG. 1, the following complicated operations are required. That is, a knock operation body (not shown in the drawing) connected to the rear end of the lead case 1 is pressed to press the lead case 1, and while compressing the knock spring 2, the chuck case 3 which is friction-fitted with the lead case 1 is simultaneously advanced to open the chuck case. After the retaining ring 4 fixed to the front end of the shaft coupling 3 is brought into contact with the inner wall 6 of the shaft coupling 5, the core case 1 is slid against the chuck case 3, and the inner step 7 of the core case 3 is attached to the rear end of the core fixing chuck 8. By contacting and pressing the core fixing chuck 8, the core fixing chuck 8 is independently advanced, and the core fixing chuck 8 is moved forward while rolling the ball 9.
is opened to the extent that the lead can freely fall, the lead is returned once, and then fed out again to obtain an appropriate amount of payout. As described above, conventional sharp pencils using ball chucks have the disadvantage that it is troublesome to correct overextended lead and that the lead tends to break when excessive writing pressure is applied to the lead.

The first purpose of the present invention is to eliminate such drawbacks, and the second purpose is to facilitate the replacement of parts by making it easier to disassemble the chuck case and core fixing chuck, which are configured to meet that purpose. .

In this invention, a spring is interposed between the outer stepped part of the chuck case containing the ball chuck and the inner stepped part of the shaft cylinder, and the core case is slidably fitted in the axial direction on the rear outer periphery of the chuck case. A knock spring stronger than the above spring is interposed between the outer step and the inner step of the shaft cylinder, and the step is provided at the rear end of the fitting sliding portion of the core case and the fitting sliding portion of the chuck case. At the same time, the spring interposed between the outer step of the chuck case and the inner step of the shaft cylinder is compressed, and the spring is pressed against the core case at a position where the spring is not fully compressed. A stopper is provided to abut against each other to prevent it from retreating, and a tapered surface is provided on the inner surface of the front end opening of the core case located in front of the sliding portion that fits into the chuck case, and a stepped portion on the inner surface of the shaft cylinder is provided. The core case is provided with a protrusion having a tapered surface that comes into contact with the tapered surface and slides against each other, and the lead case is provided with an axial slit from its front end.

The operation will be explained below with reference to the drawings (FIG. 2).

The drawing shows a finger-feeding mechanical pencil that is an embodiment of the present invention.

When excessive writing pressure is applied to the lead fixing chuck 11, the spring 16 interposed between the outer step 13 of the chuck case 12 and the inner step 15 of the shaft tube 14 is compressed, thereby fixing the lead in the chuck case 12 and its interior. The chuck 11 moves back together and absorbs the excessive writing pressure, thereby preventing the lead from breaking. In order to compress the spring 16 to a degree that does not reach full compression, the elastic force of the knock spring 21 connects the stepped portion 19 provided at the rear end of the fitting sliding portion 18 of the core case 17 and the stepped portion 20 of the chuck case 12. When the stopper 2 is brought into contact with the core case 17 and the retraction of the core case 17 is at the desired position, the stopper 2
2 prevents this. A method for maintaining the spring 16 between the chuck case 12 and the shaft cylinder 14 in an appropriately compressed state is to frictionally fit the fitting and sliding portion 18 of the core case 17 and the chuck case 12 and set the frictional force appropriately. Although this is possible, it is not practical due to problems such as wear, lubrication, and machining accuracy. On the contrary, as in the present invention, the core case 1
7 and the step 20 of the chuck case 12 are brought into contact with each other by a knock spring 21, and the core case 1
If the stopper 7 is stopped at a desired position by the stopper 22, such a difficult problem can be solved. In this case, check case 1 if excessive pen pressure is applied.
The frictional force of the fitting sliding portion 18 is smaller than the force of the spring 16, and the friction force between the rear end of the core fixing chuck 11 and the inner surface stepped portion 23 of the core case 17 is such that the sliding portion 2 can slide against the core case 17. A required gap 24 must be set between them.

Next, if you want to correct the overextended lead, proceed as follows.

The shaft tube 14 is stood up, the tip of the core is pressed against a desk surface, etc., and the core fixing chuck 11 is pushed backward and moved (at this time, the chuck case 12 is also pressed through the ball 25, compressing the spring 16 and moving backward at the same time). When the rear end of the core fixing chuck 11 is brought into contact with the inner surface step 23 of the core case 17, the rear end of the core fixing chuck 11 is brought into contact with the inner surface step 2 of the core case 17.
3, the core fixing chuck 11 moves forward relative to the chuck case 12 and is released from the force of the ball 25, thereby loosening the core fixation. At this time, the tip of the lead that has come out too far is pressed to make the lead retract, but the amount of retraction is increased by the distance β that the lead fixing chuck 11 fixes the lead and returns to the front after the desired retraction amount α. I'll keep it. Then, when the pressure on the lead is released, the chuck set (which collectively refers to the chuck case 12 and the lead fixing chuck 11 etc. inside it) holds the lead and moves forward by β, and eventually the lead reaches the desired length α.
This means that you are immersed in it, and the excessive protrusion of the core is corrected.

Next, the core case 1 fitted into the chuck case 12
By advancing the core case 17, the tapered surface 27 provided on the inner surface of the front end opening of the shaft tube 14 comes into contact with the tapered surface 29 provided on the protrusion 28 provided on the rear surface of the inner step 15 of the shaft tube 14, and the core case 17 is moved forward. The inner diameter is enlarged by the slit (not shown in the drawing) provided in the lead case 17 and the contact between the step 19 of the lead case 17 and the step 20 of the chuck case 12 is eliminated, so that the chuck case 12 can be removed from the lead case 17. It's easy to do.
It is of course easy to assemble the chuck case 12 to the core case 17 due to the tapered surface 27 of the core case 17. In addition, during the disassembly process, the shaft coupling 30 is removed from the shaft cylinder 14.
Accidents such as the chuck case 12 popping out due to the elasticity of the spring 16 even when removed from the core case 17 are also prevented by the contact between the stepped portion 19 of the core case 17 and the stepped portion 20 of the chuck case 12.

As mentioned above, in this invention, when excessive writing pressure is applied, the chuck set retreats due to the spring and acts as a cushion, which prevents the lead from breaking, and also eliminates the need for troublesome operations such as notching the rear end. It has the effect of being able to adjust the length simply by pressing on it. Another advantage is that the chuck case and core case can be easily disassembled, making it easier to replace parts.

[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 touch, 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. DESCRIPTION OF SYMBOLS 1...Core case, 2...Knot spring, 3...Chuck case, 4...Retaining ring, 5...Shaft coupling, 6...Inner wall, 7...Inner surface step, 8...Core fixing chuck, 9... Ball, 10... Core fixing hole, 1
DESCRIPTION OF SYMBOLS 1... core fixing chuck, 12... chuck case, 13... outer step part, 14... shaft cylinder, 15...
Inner step part, 16... Spring, 17... Core case, 1
8... Fitting sliding part, 19... Step part, 20... Step part, 21... Knock spring, 22... Stopper,
23... Inner surface step, 24... Gap, 25... Ball, 26... Core fixing hole, 27... Tapered surface, 28
...Protrusion, 29...Tapered surface, 30...Shaft coupling.

Claims (1)

[Scope of Claim for Utility Model Registration] A spring is interposed between the outer step of the chuck case with the ball chuck inside and the inner step of the shaft cylinder, and a core case is fitted to the rear outer periphery of the chuck case so as to be slidable in the axial direction. A knock spring stronger than the above spring is interposed between the outer step of the core case and the inner step of the shaft cylinder, and the step provided at the rear end of the fitting sliding part of the core case and the chuck case are connected to each other. The stepped portion at the rear end of the fitting sliding portion is brought into contact with the stepped portion, and the spring interposed between the outer stepped portion of the chuck case and the inner stepped portion of the shaft cylinder is compressed, but the spring does not reach full compression. A stopper is provided to abut against the core case at a position to prevent it from retreating, and a tapered surface is provided on the inner surface of the front end opening of the core case located in front of the sliding portion that fits into the chuck case, and a taper surface is provided on the inner surface of the front end opening of the core case, and A sharp pencil characterized in that the stepped portion is provided with a protrusion having a tapered surface that contacts the tapered surface and slides against each other, and the lead case is provided with an axial slit from the front end thereof.