JP4784313B2 - Pencil lead polisher - Google Patents

Description

  The present invention relates to a pencil lead polisher, and more particularly to a pencil lead polisher for a pencil used in a pencil scratch test described in JIS K5400 and JIS K5600.

  The pencils used in the pencil scratch test described in JIS K5400 and JIS K5600, which are used to examine the scratch resistance of the coating film, have a cylindrical shape, and the length of the pencil core is within the specified range. Need to be. Moreover, it is necessary to grind so that the tip of the pencil lead is flat and the corner is sharp.

  Conventionally, in order to obtain a pencil suitable for the standard, first, the xylem is shaved so that only a certain amount of core is left, and then the person holds the pencil and puts the pencil core vertically on abrasive paper placed on a flat surface. However, I was sharpening to draw a circle.

  However, when a person grinds using abrasive paper, the verticality is visually confirmed, and there is a problem that the shape of the tip of the pencil lead varies with each grinding. In particular, there has been a problem that the variation in the radius of curvature at the tip end angle of the pencil core increases with each polishing. For this reason, it was difficult to perform a pencil scratch test with good reproducibility, and it was difficult to properly evaluate the scratch resistance of the coating film.

Usually, when the pencil lead is polished, the side of the pencil is sharpened. However, since the pencil for the pencil scratch test described in JIS K5400 and JIS K5600 has a prescribed pencil state as described above, a pencil suitable for this is reproduced by the above method. You can't get good.
JP-A-6-219095

  Therefore, the present invention has been made to solve the problem that the curvature radius of the pencil core tip angle of the pencil used in the pencil scratch test increases with each polishing, and obtains the same pencil core tip angle with good reproducibility. An object of the present invention is to provide a pencil lead polishing machine that can handle the above.

The present invention according to claim 1 is a pencil lead polisher for flattening a lead tip of a pencil having a cylindrical shape used in a pencil scratch test, the pencil polisher comprising: a pencil fixing part; It consists of a polishing mechanism,
The pencil fixing part includes a bottom plate,
A lower pencil holding part that is fixed to the bottom plate and has a groove of an angle of 60 degrees on which a pencil is placed;
An upper pencil holding part for holding a pencil placed on the lower pencil holding part;
A fixing screw for fixing the lower pencil holding part and the upper pencil holding part;
It is fixed to the bottom plate, and consists of a stopper that limits the movement of the polishing mechanism,
And the lower pencil holding part, the upper pencil holding part and the fixing screw are provided at two places on the bottom plate,
The polishing mechanism is formed by attaching a polishing part to a movable part,
And the said grinding | polishing part is selected from the 400th abrasive paper prescribed | regulated to JISR6252, or the abrasive paper of P1000,
The movable portion is L-shaped, and the polishing portion is provided so as to be positioned perpendicular to the bottom plate upper surface of the bottom plate,
The stopper is L-shaped, and is provided such that the upper surface of the stopper and the lower surface of the stopper are positioned perpendicular to the upper surface of the bottom plate of the bottom plate,
The axial direction of the pencil held by the pencil fixing part and the bottom plate upper surface of the bottom plate are in a parallel relationship,
The axial direction of the pencil held by the pencil fixing part and the upper surface of the stopper are in a vertical relationship,
The axial direction of the pencil held by the pencil fixing part and the upper surface of the movable part are in a vertical relationship ,
The pencil lead polishing machine is characterized in that the polishing of the pencil is finished when the upper surface of the stopper comes into contact with the upper surface of the movable part .

  According to the present invention, it is possible to reduce the variation in the curvature radius at the pencil core tip angle for each polishing. That is, a pencil for use in the pencil scratch test can be prepared in a certain shape. For this reason, the reproducibility of the pencil scratch test is improved, and the scratch resistance of the coating film can be legitimately evaluated.

  An example of the pencil lead polisher of the present invention will be described with reference to FIG.

  The pencil lead polisher of the present invention is shown. It consists of a pencil fixing part 20 composed of 21 to 25 parts and a polishing mechanism part 30 composed of 30 to 31 parts.

An example of the pencil fixing unit 20 is shown in detail.
The pencil fixing unit 20 includes a lower pencil holding part 22 having a groove for placing the pencil 10 on the bottom plate 21, an upper pencil holding part 24 for holding the pencil placed on the lower pencil holding part 22 so as not to move, and a lower pencil holding part 22. And a fixing screw 25 for fixing the upper pencil holding portion 24, and a stopper 23 for restricting the movement of the polishing mechanism 30 by polishing by applying the tip of the core of the pencil 10 and the polishing mechanism 30 at right angles. The lower pencil holding part 22 and the stopper 23 are fixed to the bottom plate 21. In addition, in order to fix a pencil firmly, the lower pencil holding part 22, the upper pencil holding part 24, and the fixing screw 25 were installed in two places as shown in FIG.

  As a material of each member constituting the pencil fixing portion 20, plastic such as acrylic and polycarbonate, metal, and wood can be used.

  The pencil fixing unit 20 may have any structure as long as the pencil can be fixed. For example, a structure in which a hole larger than the diameter of the pencil is formed in the pencil holding portion and the pencil passing through the hole is fixed by a screw extending toward the center of the hole. Moreover, as for the location which fixes a pencil, 2 or more locations are desirable about the length direction of a pencil.

  Next, details of the polishing mechanism 30 will be described. The polishing mechanism unit 30 is configured by mounting a polishing unit 32 on a movable unit 31.

  As a material of the movable part 31, plastics such as acrylic and polycarbonate, metal, and wood can be used.

  As the polishing paper used for the polishing unit 32, in the case of the JIS K5400 test, No. 400 polishing paper defined in JIS R6252, and in the case of the JIS K5600 test, 3M-P1000 defined by the standard can be used.

  Since the polishing unit 32 is contaminated with a pencil lead, it is desirable that the polishing unit 32 be configured so that it can be easily replaced. For example, the polishing unit 32 may be attached to the movable unit 31 with a double-sided tape.

  The axial direction of the pencil 10 and the polishing unit 32 of the polishing mechanism unit 30 are provided so as to maintain a position perpendicular to each other. For this reason, the bottom plate 21, the stopper 23 of the pencil fixing part 20, and the movable part 31 of the polishing mechanism part 30 are provided as follows.

  The movable portion 31 is L-shaped and is provided so that the polishing portion 32 is positioned perpendicular to the bottom plate upper surface c of the bottom plate 21.

  The stopper 23 is L-shaped and is provided such that the stopper upper surface a and the stopper lower surface c are positioned perpendicular to the bottom plate upper surface c of the bottom plate 21.

  Further, the axial direction of the pencil 10 held by the pencil fixing unit 20 and the bottom plate upper surface c are in a parallel relationship, and the axial direction of the pencil 10 and the stopper upper surface a are in a vertical relationship, and are movable with respect to the axial direction of the pencil 10. The upper part surface b has a vertical relationship. An alignment mark for the movable portion 31 may be provided on the bottom plate 21 so that this positional relationship can be maintained during polishing.

  At the end of polishing, the stopper upper surface a and the movable portion upper surface b come into contact with each other while maintaining a vertical positional relationship. For this reason, the stopper upper surface a and the movable part upper surface b are horizontal, and both surfaces are in contact with each other without distortion. As a result, the pencil lead that is perpendicular to the stopper upper surface a and the movable portion upper surface b can also be polished vertically, and variations in the radius of curvature at the pencil core tip angle can be reduced. . Further, the polishing can be completed with a predetermined length.

  In addition, in order for the stopper upper surface a and the movable portion upper surface b to come into contact with each other and the polishing is finished, it is desirable that the stopper lower surface d and the movable portion lower surface e do not contact.

Next, the detail of the usage method of the pencil lead polisher of this invention is shown.
The pencil 10 is fixed to the pencil fixing part 20 with the tip of the pencil lead protruding from the stopper upper surface a by the amount to be polished.

  Thereafter, the pencil core is polished by moving the polishing section 32 attached to the movable section 31 to the left and right, for example, while pressing the polishing section 32 perpendicularly to the pencil axis. At this time, the alignment mark on the bottom plate 21 may be referred to so that the movable part upper surface b and the pencil axial direction are always perpendicular to each other.

  The polishing is finished when the stopper upper surface a and the movable portion upper surface b come into horizontal contact with each other and the pencil core is no longer polished.

  When polishing, if the axial direction of the pencil and the movable part upper surface b are perpendicular to each other, it may be moved by one or both of the pencil fixing part 10 and the polishing mechanism part 30. For example, the structure which fixes the grinding | polishing part 32 to the baseplate 21, and makes the pencil fixing | fixed part 20 movable may be sufficient.

  First, the pencil lead grinder shown in FIG. 1 was produced using a stainless steel plate having a thickness of 10 mm. The lower pencil holding part is provided with a triangular groove at an angle of 60 ° to match the hexagonal shape of the pencil axis, the pencil is fitted into this groove, and the upper pencil holding part is used to screw the pencil. Was fixed. Moreover, the No. 400 sandpaper prescribed | regulated to JISR6252 was affixed on the movable part using the double-sided tape.

  Next, the tip of a 3H pencil centered in a cylindrical shape was polished using the pencil jig so that the pencil lead length was 3 mm. By this method, the cores of five pencils were polished.

  Next, the radius of curvature of the pencil lead tips of the five pencils obtained was measured.

Here, it was determined that the radius of curvature was obtained by the following method. First, using a laser microscope (OLS1100, manufactured by Olympus), a corner profile of the polished pencil lead was taken. Next, as shown in FIG. 2, an arc within a 50 μm width of the pencil where the polished surface A at the tip of the pencil core and the side surface B of the pencil core in a columnar shape contact was measured. The shape of the arc was extracted as coordinate data, and the curvature radius was obtained by fitting the equation of the circle.

A radius of curvature was obtained for each of the five pencils. The results are shown in FIG.

  Next, a pencil scratch test specified in JIS K5400 was performed to confirm the test reproducibility.

The sample used was a polyethylene terephthalate (PET) having a thickness of 80 μm coated with about 5 μm of polymethyl methacrylate (PMMA). A pencil scratch test was performed by applying a load of 45 ° and 1000 ± 50 gf from the opposite side of the polished surface of the polished pencil to the PMMA coated surface. In the pencil scratch test, scratches with a length of 30 mm were performed 5 times at intervals of 5 mm on the center portion of a 50 mm × 60 mm sheet, and the presence or absence of scratches was confirmed on the surface of the test piece from an angle of 45 degrees. Of the 5 scratches, the number x of scratches was counted and evaluated as x / 5.

Five tests were conducted to inspect the resistance of the coating film. The results are shown in Table 1.

<Comparative example>
For the 3H pencil, without using the pencil lead grinder, hold the pencil and put the pencil lead on the sandpaper of No. 400 prescribed in JIS R6252 placed on a flat surface. The tip of the pencil lead was polished so as to draw a circle to 3 mm. By this method, the cores of five pencils were polished.

  In the same manner as in the example, the radius of curvature of the pencil lead tips of the five pencils obtained was measured. A radius of curvature was obtained for each of the five pencils. The results are shown in FIG.

  As in the examples, a pencil scratch test defined in JIS K5400 was performed to confirm the test reproducibility. Five tests were conducted to inspect the resistance of the coating film. The results are shown in Table 1.

<Evaluation>
As shown in FIG. 3, the radius of curvature of the tip of the pencil lead polished using the pencil lead polisher of the present invention is less varied than the pencil that has been polished by the conventional polishing method. Was confirmed.

Count the number x of scratches and evaluate to x / 5. If it is 3/5 or more, it is judged that the coating film has resistance to the pencil hardness used.

  Also, from Table 1, the scratch test conducted using a pencil whose tip has been polished by a conventional polishing method has a mixture of pass / fail of scratch resistance. In this state, it is accurate to evaluate the pencil scratch resistance of a sample. It was impossible because of low. However, the scratch test results performed using a pencil whose core tip has been polished using the pencil lead polisher of the present invention show that the scratch resistance results are not mixed, and the reproducibility of the scratch test is improved. Was confirmed.

  The pencil lead polisher of the present invention can be used for improving the accuracy of a pencil scratch test or the like because it enables stabilization of the tip shape of the pencil lead.

It is the schematic of the pencil lead polisher by this invention, (a) Side view, (b) Front view. It is the schematic for demonstrating how to obtain | require the curvature radius of the corner | angular of a pencil lead, (a) A general view, (b) It is an enlarged view. It is the graph which plotted the curvature radius of the tip angle of the pencil lead ground with the conventional method and the pencil lead polisher of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pencil 20 ... Pencil fixing part 21 ... Bottom plate 22 ... Lower pencil holding part 23 ... Stopper 24 ... Upper pencil holding part 25 ... Fixing screw 30 ... Polishing mechanism part 31 ... Movable part 32 ... Polishing part a ... Stopper upper surface b ... Movable part upper surface c ... Bottom plate upper surface d ... Stopper lower surface e ... Movable part lower surface A ... Pencil core tip polished surface B ... Pencil core side surface

Claims (1)

A pencil lead polisher for flattening the tip of a cylindrical pencil core used in the pencil scratch test, the pencil polisher comprising a pencil fixing part and a polishing mechanism part,
The pencil fixing part includes a bottom plate,
A lower pencil holding part that is fixed to the bottom plate and has a groove of an angle of 60 degrees on which a pencil is placed;
An upper pencil holding part for holding a pencil placed on the lower pencil holding part;
A fixing screw for fixing the lower pencil holding part and the upper pencil holding part;
It is fixed to the bottom plate, and consists of a stopper that limits the movement of the polishing mechanism,
And the lower pencil holding part, the upper pencil holding part and the fixing screw are provided at two places on the bottom plate,
The polishing mechanism is formed by attaching a polishing part to a movable part,
And the said grinding | polishing part is selected from the 400th abrasive paper prescribed | regulated to JISR6252, or the abrasive paper of P1000,
The movable portion is L-shaped, and the polishing portion is provided so as to be positioned perpendicular to the bottom plate upper surface of the bottom plate,
The stopper is L-shaped, and is provided such that the upper surface of the stopper and the lower surface of the stopper are positioned perpendicular to the upper surface of the bottom plate of the bottom plate,
The axial direction of the pencil held by the pencil fixing part and the bottom plate upper surface of the bottom plate are in a parallel relationship,
The axial direction of the pencil held by the pencil fixing part and the upper surface of the stopper are in a vertical relationship,
The axial direction of the pencil held by the pencil fixing part and the upper surface of the movable part are in a vertical relationship,
The pencil lead polishing machine is characterized in that the polishing of the pencil is finished when the upper surface of the stopper comes into contact with the upper surface of the movable part.