JPH0469298B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a moving body guide shaft suitable for use in a print head guide mechanism of an office equipment device, particularly a small printer.

[Conventional technology]

Conventionally, in order to guide the print head to a predetermined position in this type of small printer, a wire drive system that uses a wire to drive the print head, a timing drive system that uses a belt to drive the printer, and a guide shaft that uses a guide shaft to drive the printer have been used. drive system is used.

FIG. 9 is a front view showing a conventional print head guide shaft, which is a main component of a guide shaft drive type drive mechanism. This print head guide shaft 1 has small-diameter support portions 1a and 1b rotatably supported by bearings (not shown) at both ends thereof. As shown in the figure, a groove 1 with a width A and a depth H and a substantially U-shaped cross section.
c is spirally formed from the right end to the left end, that is, continuously in the axial direction,
This single groove forms a print head guide groove.
The width and depth dimensions of this spiral groove 1c are the 11th
The cylindrical protrusion 2b is formed to be slightly larger than the width A' and height H' of the cylindrical protrusion 2b protruding from the inner surface of the through hole 2a of the print head 2 as a moving body as shown in the figure. The inner diameter B' of the through hole 2a of the head 2 is slightly larger than the outer diameter of the print head guide shaft 1. Therefore, the print head 2 is loosely inserted into the print head guide shaft 1 through the through hole 2a, and after being loosely inserted, the protrusion 2b of the print head 2 is inserted into the spiral groove of the print head guide shaft 1. 1c are adapted to engage with each other. That is,
By rotating the print head guide shaft 1 in a predetermined direction, the protrusion 2b of the print head 2 is pushed by the side wall surface 1d or 1e of the groove 1c of the print head guide shaft 1, and this pressing force causes the protrusion 2b to form the spiral shape of the groove 1c. As the protrusion 2b slides, the entire print head 2 slides in a predetermined direction on the print head guide shaft 1. Furthermore, when the print head guide shaft 1 is rotated in the opposite direction from this state, the print head 2 slides in the opposite direction to that described above. This moving speed is determined by the rotational speed of the print head guide shaft 1 and the pitch P of the helical groove 1c. That is, by moving the print head 2 while controlling the rotational speed and direction of the print head guide shaft 1 using a drive motor and a control device (not shown), highly accurate print head guide operation in a small printer can be achieved. be able to. Since the print head 2 can be guided with high precision according to the rotation of the print head guide shaft 1, it has the advantage of being able to have a more compact drive mechanism than other wire drive systems or timing drive systems. have.

[Problem that the invention seeks to solve]

However, despite the above-mentioned advantages, such a guide shaft drive system is actually less popular than other wire drive systems or timing drive systems. This is because the print head guide shaft 1 used in the guide shaft drive system has extremely low productivity and is expensive. That is, to explain the manufacturing process of the print head guide shaft 1, first, a round bar with a predetermined outer diameter is cut into a predetermined length, and then a spiral groove 1c is cut using a lathe or a special milling machine. Then, in order to remove burrs generated on the outer circumferential surface due to this cutting process and to make the outer circumferential surface smooth, outer diameter grinding is performed, and further, in order to smooth the side wall surface and bottom surface of the spiral groove 1c. Perform groove grinding. Then, the entire surface is buffed to form a print head guide groove. As is clear from this manufacturing process, the spiral groove 1c
In order to form the printing head guide shaft 1, cutting is performed using a lathe or a special milling machine, and the time required for this cutting is extremely long, resulting in extremely poor productivity of the printing head guide shaft 1 and making it expensive. There is. In addition, the groove grinding time for grinding the cut groove 1c also occupies a considerable amount of time. Therefore, the problem has been how to shorten the machining time required for groove cutting and groove grinding and increase productivity.

Therefore, the applicant attempted to form the spiral groove 1c of the conventional print head guide shaft 1 shown in FIG. 9 by rolling using a die instead of by cutting.

That is, the material of the print head guide shaft 1 (a round bar cut to a predetermined length and having a predetermined outer diameter) is rotatably supported and fixed so that the shaft center does not move, as shown in FIG. A rest 5 provided between a round die 3 and a round die 4 which is rotatably supported and whose axis is movable in the left-right direction in the figure is placed on the groove 1c. It was decided that the material would be rolled and formed. In other words, the round dies 3 and 4 have a die shape having the same helix angle as the spiral groove 1c formed on the outer peripheral surface of the material of the workpiece to be rolled, that is, the printing head guide shaft 1. By rotating the round dies 3 and 4 in the direction of the arrow and moving the axis of the round die 4 in the left-right direction to press the material with a predetermined pressure, the material rotates and the spiral groove 1c is formed. is formed without cutting. In this way, by forming the spiral groove 1c by rolling rather than cutting, the time required for forming the groove can be significantly shortened compared to the case where the groove is formed by cutting. Additionally, unlike cutting, no chips are produced, so post-processing can be carried out smoothly. Furthermore, an important point is that the surface of the groove 1c can be made into a mirror-like smooth beautiful finished surface (3S or less) at the same time as the rolling process. That is, FIG. 5 is a metallographic diagram of a groove formed by cutting, and FIG. 6 is a metallographic diagram of a groove formed by rolling. As can be seen from the figure, due to rolling, the metal structure is composed of a dense flow, so the precision of the rolling die is transferred to the surface, resulting in a mirror finish with a small coefficient of friction. In contrast, the metallographic structure obtained by cutting as shown in FIG. 5 remains the same as the metallographic structure of the material, and the surface of the groove is determined by the accuracy of the cutting tool, and is generally limited to 6S. Therefore, there is no need to perform groove cutting as in the case of cutting. Furthermore, it goes without saying that the fatigue limit, surface hardness, tensile strength, etc. are improved by rolling.

However, such a print head guide shaft 1
The pitch P of the spiral groove 1c needs to be set large in order to increase the moving speed of the print head 2 shown in FIG. ) When attempting to perform the rolling process, there was a problem in that the rolling balance was lost and the print head guide shaft 1 itself was greatly curved. In other words, in the rolling device shown in FIG. 4, the rolling pressures of the round dies 3 and 4 on the material are not balanced, and an unbalanced pressing moment is created on both ends of the material. As a result, both ends of the material were severely curved. Therefore, in order to correct this curvature, a straightening operation must be performed, but the time required for this straightening operation is excessively long.

In addition, in the above-mentioned rolling process, the groove 1c
The material flows and bulges on the upper edge surface due to the rolling pressure, resulting in a raised portion 1d as shown in FIG. This raised portion 1d is used for guiding the printing head 2 and becomes an obstacle, so it is necessary to cut it out entirely. That is, the pitch P of the spiral groove 1c of the print head guide shaft 1 is set large in order to increase the moving speed of the print head 2, as described above, and if this pitch P is large, the raised portion 1d will become a rolled screw. It cannot be used as a crest like this, and it actually obstructs the smooth sliding movement of the printing head 2. In addition, in order to shorten the grinding time, instead of removing the entire raised portion 1d by grinding, only the top surface of the raised portion 1d is ground to make it flat as shown in FIG. One possible method is to use it as a sliding contact surface with the inner surface, but in this way, the ground surface 1e of this raised portion 1d and the printing head 2
There is a problem in that the contact with the inner surface of the printing head 2 becomes unbalanced, making it impossible to smoothly guide the printing head 2. In other words, the groove 1c of the print head guide shaft 1
The pitch P of the print head 2 is set large as described above, and the length L of the print head 2 is
(FIG. 11b) is small, the proportion of contact between the inner surface of the print head 2 and the ground surface 1e becomes uneven, making it impossible to perform a smooth guiding operation.
Therefore, the raised portion 1 that rises during the rolling process
All d must be removed by polishing.

However, for this reason, even if the entire raised portion 1d is removed by grinding, the outer diameter D of the material shown in FIG. 7 cannot be used as a sliding contact surface with the inner surface of the printing head 2. This is because when the printing head guide shaft 1 forms the groove 1c in a spiral shape,
The print head 2 is slightly twisted and misaligned, and if an attempt is made to guide the print head 2 with the outside diameter D of the material whose center is off, the print head 2 cannot be inserted loosely. Alternatively, even if it can be inserted loosely, there is a problem that it cannot be guided smoothly. Therefore, in order to correct the center deviation due to this twist, it is necessary to perform outer diameter grinding by centerless grinding to the outer diameter _D1 in a manner that cuts in slightly more than the outer diameter D of the material, as shown in FIG. In other words, the outer diameter D of the material must be determined so that this outer diameter _D1 is equal to the finished outer diameter B of the print head guide shaft 1 by cutting shown in FIG.
If the finished outer diameter B is 7.9φ, the material outer diameter D is
Requires 8φ. At this time, the raised portion 1d that rises on the upper edge surface of the groove 1c increases the depth H of the groove 1c by 1.
If it is mm, it will rise 0.4mm from the outer circumferential surface of the material.
In other words, in order to obtain the print head guide shaft 1 with a finished outer diameter of 7.9φ as shown in FIG. 9 by rolling, a material with an outer diameter of 8φ is prepared, and after rolling the groove 1c The outer diameter must be ground to a thickness of 0.45 mm from the top surface of the raised portion 1d that rises on the upper edge surface of this groove 1c.

[Means for solving problems]

The present invention has been made in view of these points, and is made by forming a continuous piece on the outer circumferential surface of a material (a round bar of a predetermined outer diameter cut to a predetermined length) by rolling in the axial direction. A spiral first groove is formed, and this first groove is formed into a spiral shape.
A continuous spiral second groove is simultaneously formed at the same pitch P ₂ between the groove pitches P ₁ by the above-mentioned rolling process, and the upper edge surfaces of the first and second grooves are A portion of the raised portion that swells up during the rolling process is ground flat from its top surface to form a sliding contact surface with the inner surface of the movable body.

[Effect]

Therefore, according to the present invention, even if the groove pitches P ₁ and P ₂ are set large in the movable body guide shaft to be manufactured, the pressing moment applied to both ends of the material during rolling is small.

In addition, the ground surface formed by grinding a part of the raised portion from its top surface can be used as a sliding contact surface without any problem in the manufactured moving body guide shaft.
There is no need to perform centerless grinding that cuts into the outer diameter of the material, the outer diameter of the material can be made smaller, and the rolling rate can also be reduced.

Regarding the moving body guide shaft manufactured by applying the present invention, if the first groove guides the moving body, the second groove becomes a waste groove, and the second groove guides the moving body. If so, the first groove becomes a waste groove. Also, even if the groove pitches P ₁ and P ₂ are set large to increase the movement speed,
It is possible to balance the contact with the inner surface of the movable body, and the sliding contact area with the inner surface of the movable body is reduced, reducing frictional resistance.

Hereinafter, a method for manufacturing a moving body guide shaft according to the present invention will be explained in detail. FIG. 1 is a front view showing an embodiment of a print head guide shaft as a moving body guide shaft manufactured by applying this method. The same reference numerals as in FIG. 9 indicate the same parts, and the explanation thereof will be omitted. On the outer circumferential surface of the print head guide shaft 6, there is a spiral groove 7 that is continuous from the right end to the left end, that is, one continuous spiral groove in the axial direction, and a spiral groove 8 that is continuous from the right end to the left end. and are simultaneously formed by rolling. That is, two spiral grooves are formed independently on the outer peripheral surface of the print head guide shaft 6, and a pitch P1 is formed between the grooves ₇ .
It looks like the groove 8 of _P2 has been rolled. In this embodiment, the pitch P ₁ of the groove 7 and the pitch P ₂ of the groove 8 are set equal, and P ₁
=P ₂ =15.89mm. Furthermore, the pitch _P3 between adjacent grooves 7 and 8 is 1/2 of the pitches _P1 and _P2 .

In addition, some of the protrusions 7a and 8a that flow and swell on the upper edge surfaces of the grooves 7 and 8 during the rolling process are flattened from the top surface with a predetermined thickness as shown in FIG. It has been ground to form ground surfaces 7b and 8b, and the entire ridge has not been ground away. In addition, during the rolling process of the grooves 7 and 8, the flow of the material forming the raised parts 7a and 8a is regulated by the die shape, and the raised parts 7a
When the top surface of 8a and 8a is ground flat to the outer diameter D ₂ , the ground surfaces 7b and 8b created by this outer diameter D ₂
R curved surfaces 77e and 8e remain below the curved surface and outward (on the protrusion side) from the upwardly extending lines 7d and 8d of the side wall surfaces 7c and 8c. By leaving such R curved surfaces 7e and 8e, when the protrusions 7a and 8a are ground, the ground surfaces 7b and 8a are removed by this grinding process.
Grinding burrs 7f and 8f as shown in FIG. 3 protruding inward from the inclined side wall surfaces 7c and 8
By being located outward from the extension lines 7d and 8d of the print head 2, it is sufficient to remove the protrusions 2b and the grooves 7 of the print head 2 shown in FIG. and 8 can be smoothly engaged.

On the other hand, the outer diameter D ₂ of this print head guide shaft 6 created by the ground surfaces 7b and 8b is equal to the finished outer diameter D ₁ (7.9φ) in FIG.
Depth from b and 8b to the bottom of grooves 7 and 8
H ₁ (Figure 2) is equal to the depth H (1 mm) in Figure 7. Therefore, the print head 2 shown in FIG. 11 is loosely inserted into the print head guide shaft 6 through the through hole 2a, and the protrusion 2b of the print head 2
and the groove 7 or 8 of the print head guide shaft 6 are adapted to engage with each other. That is, since the two grooves 7 and 8 are each independently formed into a spiral shape, when the protrusion 2b of the print head 2 is engaged with one of the grooves 7 or 8, the other groove 8 or 7 is designed to be a waste groove that does not contribute to guiding the print head 2. Two grooves like this 7
It is free to choose which groove among the grooves and 8 to guide the print head 2. By doing so, it is possible to reduce the frictional resistance when guiding the print head 2, and to balance the contact between the inner surface of the print head 2 and the ground surfaces 7b and 8b of the guide shaft, resulting in smooth and high speed printing. This makes it possible to perform guidance operations.

That is, the grooves 7 and 8 of the print head guide shaft 6
The pitches P ₁ and P ₂ are the same as the pitch P of the print head guide shaft 1 made by conventional cutting (P ₁ =P ₂ =P=15.89 mm), and are set larger. Therefore, no matter which groove is used for guiding, the moving speed of the printing head 2 can be increased as in the conventional case. Also, at this time, the proportion of contact between the inner surface of the print head 2 and the ground surfaces 7b and 8b of the guide shaft is such that the length L of the print head 2 is smaller than the pitches _P1 and _P2 of the grooves 7 and 8. Even in this case, since the grooves 7 and 8 are substantially formed by rolling with a pitch _P3 , they are uniform and smooth guiding operation can be performed. In addition, the contact area at this time is the entire surface of the single printing head guide shaft 1, whereas the contact area is
Only the total area of grinding surfaces 7b and 8b becomes 1
This can be reduced to 1/3 or less compared to the length of the printing head guide shaft 1. Therefore, the frictional resistance when guiding the printing head can be reduced to less than 1/3, and even higher speed guidance is possible. Further, at this time, the stepped portion 9 (FIG. 2) formed by the raised portion 7a of the groove 7 and the raised portion 8a of the groove 8 can be used as an oil sump, so that the guiding operation can be made even smoother.

On the other hand, the two grooves 7 and 8 are rolled in this way, and the top surfaces of the protrusions 7a and 8a that swell up during the rolling process are ground, and the ground surfaces 7
By using b and 8b as sliding contact surfaces with the inner surface of the print head, the time for grinding the outer diameter can be significantly shortened compared to the case where a single print head guide shaft 1 is formed by rolling. At the same time, the outer diameter of the material can be reduced. That is, in the print head guide shaft 1 that rolls a single groove,
(See figure), if the finished outer diameter _D1 is 7.9φ, the material outer diameter D needs to be 8φ. Further, when the depth H of the groove 1c is 1 mm, the protruding portion 1d protrudes by 0.4 mm from the outer peripheral surface of the material. Therefore, in order to obtain the print head guide shaft 1 having an outer diameter _D1 , it was necessary to perform outer diameter grinding to a thickness of 0.45 mm from the top surface of the raised portion 1d. However, according to the two-strip print head guide shaft 6 according to the present embodiment, the ground surfaces 7b and 8 of the protrusions 7a and 8a that swell during the rolling process.
These ground surfaces 7b and 8b can be used as sliding contact surfaces with the inner surface of the printing head.
It is sufficient to set the outer diameter D ₂ up to the finished outer diameter D ₁ in FIG. That is, in this embodiment, it is sufficient to set D ₂ =7.9φ, and when the top surfaces of the protrusions 7a and 8a are ground so that D ₂ =7.9φ, the twist of the print head guide shaft 6 due to the rolling process will be reduced. The grinding surface 7 is suitable for use in guiding the printing head.
The material outer diameter D ₃ and the rolling depth H ₂ (Fig. 2) may be set so as to obtain the groove depth H ₁ (1 mm). In this example, the material outer diameter D ₃
When 7.2φ and rolling depth H ₂ is 0.65mm, the raised part 7
a and 8a are raised 0.45 mm from the outer circumferential surface of the material, and by simply grinding the outer diameter to a thickness of 0.1 mm from the top surface of the raised portions 7 a and 8 a, D ₂ = 7.9φ and the center deviation due to twisting of the guide shaft is corrected. It was also possible to obtain ground surfaces 7b, 8b and groove depth H ₁ =1 mm suitable for use in guiding the printing head. In other words, when rolling a single groove, an outer diameter of 8φ was required and the outer diameter had to be ground to a thickness of 0.45 mm, but when rolling a groove like this, two grooves were rolled. For the printing head guide shaft 6 to be shaped, the outer diameter of the material may be 7.2φ, and it is only necessary to grind the outer diameter to a thickness of 0.1 mm, making it lightweight and inexpensive, and the time for grinding the outer diameter can be significantly shortened. Also, when comparing the rolling processing rates for one thread and two threads, we find that in the case of one thread, a groove of 1.1 mm on one side is made on an 8φ material, and in the case of two threads, a groove of 1.1 mm on one side is made on a 7.2φ material. A groove of 0.65mm on one side is rolled. Therefore, if the rolling rate is determined as η = rolling groove depth x 2 / outer diameter of material x 100 (%), in the case of one thread, η≒28 (%), and 2
In the case of rows, η≒18 (%). In other words, the rolling rate is improved by about 10% in the case of two threads compared to the case of one thread. The smaller the rolling rate η, the better.
In particular, cracks during rolling are improved.

By the way, the curvature at both ends of the guide shaft, which was extremely problematic when rolling a single groove, is extremely small in such a print head guide shaft 6.

That is, on the outer circumferential surface of the print head guide shaft 6, a spiral groove 7 having a pitch _P1 as shown in FIG. 1 and a spiral groove 8 having a pitch _P2 as shown in FIG. Rolling is carried out using a device, and the balance of rolling pressure between the round dies 3 and 4 at this time is extremely good, and the unbalanced pressing force applied to both ends of the material is minimal. Become. In other words, the groove 7 of the pitch P ₁ and the groove 8 of the pitch P ₂ are essentially rolled at the same time at the pitch P ₃ , which is narrower than the pitches P ₁ and P ₂ , and as a result, The interval between the presses of the round dies 3 and 4 that press the material becomes narrower. As a result, the pressing moment applied to both ends of the material during the rolling process is reduced, and as this pressing moment is reduced, the curvature is minimized. Therefore, the time required for the correction work to correct this curvature can also be significantly shortened. In this example, the length was shortened by more than 1/2 compared to the case of a single groove.

In this embodiment, there are two spiral grooves, but the number of spiral grooves is not limited to two, and a plurality of spiral grooves may be rolled. By doing so, it becomes possible to guide the printing head through spiral grooves with a larger pitch.

Further, in this embodiment, a case where the present invention is used as a print head guide mechanism of a small printer has been described, but the present invention is not limited to small printers, nor is it limited to only print head guides.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, even if the groove pitches P ₁ and P ₂ are set large in the moving body guide shaft to be manufactured, the pressing moment applied to both ends of the material during rolling process is It is small and the material has little curvature, so the time required for straightening work is reduced.

In addition, instead of removing all of the protrusions that bulge out due to the rolling process, a part of them is ground flat from the top surface to obtain a ground surface. Since it can be used as a sliding contact surface without any problems, there is no need to perform centerless grinding that cuts into the outer diameter of the material, making it possible to reduce the outer diameter of the material and shorten the time for grinding the outer diameter. Furthermore, since the rolling rate is reduced, cracking during rolling is improved.

Regarding the moving body guide shaft manufactured by applying the present invention, if the first groove guides the moving body, the second groove becomes a waste groove, and the second groove guides the moving body. In this case, the first groove becomes a waste groove, and it is free to choose which groove to use for guiding the moving body. Even if the groove pitches P ₁ and P ₂ are set large to increase the moving speed,
It is possible to balance the contact with the inner surface of the moving body, and since the sliding contact area with the inner surface of the moving body is reduced, frictional resistance is reduced, and smooth and high-speed guiding operation is possible.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of a printing head guide shaft as a moving object guide shaft manufactured by applying the present invention, and Fig. 2 shows a printing head to be rolled and formed on the outer peripheral surface of this guide shaft. A cross-sectional view showing the shape of the guide groove. Figure 3 is a cross-sectional view showing the grinding burrs that are generated when the raised part on the upper edge of the groove is ground during rolling. Figure 4 is a cross-sectional view showing the shape of the print head guide groove. A schematic configuration diagram of the rolling device used for rolling, Figure 5 is a metal structure diagram when the print head guide groove is cut, and Figure 6 is a metal structure when the print head guide groove is rolled. Fig. 7 is a cross-sectional view showing a raised part raised on the upper edge surface of this groove by rolling process, Fig. 8
The figure is a cross-sectional view showing the state where the top surface of this raised part has been ground, FIG. 9 is a front view showing a conventional print head guide shaft having one print head guide groove, and FIG. 10 is a print on this guide shaft. A sectional view showing the shape of the head guide groove, and FIGS. 11a and 11b are a schematic front view and side view of a print head guided using this print head guide shaft. 6... Print head guide shaft, 7, 8... Groove, 7a, 8
a... Raised portion, 7b, 8b... Grinding surface, 7c, 8c...
Side wall surface, 7e, 8e...R curved surface, 7f, 8f...grinding burr.

Claims (1)

[Claims] 1. A continuous spiral first groove is formed on the outer circumferential surface of the material by rolling in the axial direction, and the pitch P ₁ of the first groove is the same. At Pitch P ₂ , one continuous spiral second groove is simultaneously formed by the rolling process, and the upper edge surfaces of the first and second grooves are formed by the rolling process. A method for manufacturing a moving body guide shaft, characterized in that a part of the raised ridge is ground flat from the top surface to form a sliding contact surface with the inner surface of the moving body.