JP6418648B2 - Fixing structure and fixing method of gear and rotating shaft - Google Patents

Description

  The present invention relates to a fixing structure between a gear and a rotating shaft, a recording apparatus using the same, and a fixing method between the gear and the rotating shaft.

  A fixing structure for fixing a gear formed by molding a resin and a rotating shaft made of a highly rigid material such as metal is used in a recording apparatus such as a printer. For example, Patent Document 1 discloses a gear fixing structure that fixes a roller shaft driving gear of a facsimile, a copying machine, or the like.

  FIG. 12 is an explanatory view showing the gear fixing structure described in Patent Document 1, FIG. 12 (a) is a front view, and FIG. 12 (b) is a cross-sectional view. The gear fixing structure is formed by press-fitting and attaching a gear 904 to the tip of the roller shaft 901. A flat portion 901a and a groove 901b are formed at the tip of the roller shaft 901. The flat surface portion 901a is formed by cutting the tip end portion of the roller shaft 901 to the tip parallel to the axis, and the cross section of the tip end portion of the roller shaft 901 has a partially cut circular shape. The gear 904 is formed of a lightweight material such as synthetic resin, and has a center hole 904b into which the tip end of the roller shaft 901 is inserted at the center. The cross-sectional shape of the center hole 904b is formed corresponding to the cross-sectional shape of the tip portion of the roller shaft 901, and the diameter of the gear inner diameter end portion 904a at the tip of the center hole 904b is larger than the other diameters of the center hole 904b. It is set small.

  The gear 904 is inserted into the tip end portion of the roller shaft 901 through the center hole 904b. At this time, since the center hole 904b of the gear 904 is smaller than the tip of the roller shaft 901, the gear 904 is press-fitted. When the gear 904 is press-fitted, the gear inner diameter end portion 904a expands by elasticity, and when reaching the groove 901b of the roller shaft 901, the gear inner diameter end portion 904a engages with the groove 901b. Since the engagement of the gear inner diameter end portion 904a with the groove 901b works to sandwich the tip end portion of the roller shaft 901, the gear 904 is fixed to the tip end portion of the roller shaft 901.

JP-A-01-164862

  However, since the roller shaft (rotating shaft) 901 has a cylindrical shaft provided with a groove 901b, the size of the center hole 904b of the gear (gear) 904 is further reduced with respect to the shaft diameter. There is a problem in that the gear 904 is deformed when trying to strengthen the torque. For this reason, it has been difficult to make it difficult for the gear 904 to come off. Further, since the tip side protrudes from the gear 904, the gear inner diameter end portion 904a engaging with the groove 901b is likely to be loose, and the gear 904 tilts toward the gear inner diameter end portion 904a when a rotational load is applied to the gear 904. There is a concern that the flare accuracy is reduced. For this reason, there has been a demand for a structure for fixing a gear and a rotary shaft that can prevent the gear from coming off more easily than the conventional structure and does not reduce the inclination or flare accuracy of the gear.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and to provide a fixing structure of a gear and a rotary shaft that can achieve both a gear retaining strength and a gear inclination and flare accuracy, and a recording apparatus using the same. And It is another object of the present invention to provide a method for fixing a gear and a rotary shaft that can achieve both the gear retaining strength and the gear inclination and flare accuracy.

  A fixing structure between a gear and a rotating shaft according to the present invention includes a resin gear provided with a center hole and a rotating shaft engaged with the center hole, and the rotating shaft is more rigid than the gear. A flat surface portion made of a high material and parallel to the axial direction; a cylindrical surface portion having different axial diameters in the first region, the second region, and the third region when viewed from the one end portion in the axial direction; A first step portion connected to the second region and the second region, and a second step portion connected to the second region and the third region, and the cylindrical surface portion includes the second step portion. The first region has a larger shaft diameter than the region and the third region, and the second region has a smaller shaft diameter than the third region, and the gear has at least a side surface of the center hole. A contact portion that contacts the first region, the third region, and the planar portion of the cylindrical surface portion; An engaging portion that engages with the first step portion has a smaller inner diameter than the shaft diameter of the first region and the third region, characterized in that it comprises.

  According to this configuration, the gear not only contacts the third region, but also contacts the first region having the maximum shaft diameter, so that the retaining strength of the gear is increased by the first region, It can be made difficult to come off the rotating shaft. Furthermore, even if the second region having a small shaft diameter in the middle is wide, the gear does not tilt and the flare accuracy does not decrease.

  In the fixing structure of the gear and the rotating shaft according to the present invention, the rotating shaft may have a shaft diameter of 104% to 106% of the first region with respect to a shaft diameter of the second region. Features.

  According to this configuration, since the difference in the shaft diameter between the first region and the second region is large, the step of the engaging portion of the gear that engages with the first step portion is large, and the gear omission in the axial direction is prevented. It can be surely prevented.

  Further, in the fixed structure of the gear and the rotating shaft according to the present invention, the gear has a strain that is compressed in a radial direction in a region in contact with the first region and the third region of the rotating shaft, The strain in the region in contact with the third region is 4% or less, and the strain in the region in contact with the first region is 6% or less.

  According to this configuration, deformation of the gear due to strain can be suppressed.

  The recording apparatus of the present invention further includes a sheet conveyance driving unit that feeds a sheet, and a recording unit that records on the sheet sent by the sheet conveyance driving unit, and the sheet conveyance driving unit is capable of rotation control. And a fixed structure of the gear and the rotary shaft.

  According to this configuration, it is possible to provide a recording apparatus in which the gears are difficult to come off and the paper feeding accuracy is good.

  The fixing method between the gear and the rotating shaft of the present invention is a fixing method between the rotating shaft and the gear which is attached by press-fitting a rotating shaft having higher rigidity than the gear into the center hole of the resin gear. The axis includes a plane portion parallel to the axial direction, a cylindrical surface portion having different axial diameters in the first region, the second region, and the third region when viewed from the one end portion in the axial direction, and the first region. And a first step portion connected to the second region, and a second step portion connected to the second region and the third region, and the cylindrical surface portion includes the second region and the second region. The shaft diameter of the first region is larger than that of the third region, and the shaft region of the second region is smaller than the third region, and the gear is press-fitted in a cross-sectional direction perpendicular to the axial direction. The front center hole is equal to or less than the cross-sectional shape formed by the flat surface portion and the cylindrical surface portion of the second region. The rotation shaft is inserted into the central hole of the gear from the one end, and at least each of the first region, the second region, and the third region is provided. A part is press-fitted.

  According to this configuration, not only the third region is press-fitted into the center hole of the gear, but also the first region having the maximum shaft diameter is press-fitted, so that the gear retaining strength is increased. It can be made larger by the area of 1 to make it difficult for the gear to come off the rotating shaft.

  In the fixing method of the gear and the rotating shaft according to the present invention, the rotating shaft may have a shaft diameter of the first region of 106% or less with respect to a size before press-fitting of the center hole, and the second The shaft diameter of the first region is 104% or more with respect to the shaft diameter of the region.

  According to this configuration, deformation of the gear due to strain can be suppressed.

  According to the fixing structure of the gear and the rotating shaft of the present invention, the gear abuts on the first region having the maximum shaft diameter, so that the retaining strength can be increased to make it difficult to come off the rotating shaft. Furthermore, even if the second region having a small shaft diameter in the middle is wide, the gear does not tilt and the flare accuracy does not decrease. Therefore, both the retaining strength of the gear and the inclination and flare accuracy of the gear can be achieved. Further, it is possible to provide a recording apparatus that can achieve both the gear retaining strength and the gear inclination and flare accuracy.

  Further, according to the method for fixing the gear and the rotating shaft of the present invention, the third region of the rotating shaft is not only press-fitted into the center hole of the gear, but the first region having the maximum shaft diameter is also provided. Therefore, it is possible to increase the retaining strength of the gear by the first region, thereby making it difficult for the gear to come off the rotating shaft. Accordingly, it is possible to achieve both the gear retaining strength and the gear inclination and flare accuracy.

It is a perspective view which shows the fixation structure of the gearwheel and rotating shaft of 1st Embodiment of this invention. It is a front view which shows the fixation structure of the gearwheel and rotating shaft of 1st Embodiment of this invention. It is a left view which shows the fixation structure of the gearwheel and rotating shaft of 1st Embodiment of this invention. It is sectional drawing cut | disconnected by the IV-IV line of FIG. It is explanatory drawing which shows the shape of a gearwheel, FIG. 5 (a) is a top view, FIG.5 (b) is sectional drawing cut | disconnected by the VV line | wire of Fig.5 (a). It is explanatory drawing which shows the shape of a rotating shaft, Fig.6 (a) is a top view, FIG.6 (b) is a front view, FIG.6 (c) is a left view. FIG. 7 is an explanatory view showing a cross section in a state where the rotation shaft of FIG. 6 has started to be inserted into the gear of FIG. 5. It is sectional drawing which shows the fixing structure of a comparative example. It is sectional drawing which shows the fixing structure of the comparative example different from FIG. It is sectional drawing which shows the fixing structure of the comparative example different from FIG. It is a fragmentary perspective view which shows the recording device of 2nd Embodiment of this invention. It is explanatory drawing which shows the conventional gear fixing structure, Fig.12 (a) is a front view, FIG.12 (b) is sectional drawing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For easy understanding, the dimensions of the drawings are appropriately changed.

[First Embodiment]
FIG. 1 is a perspective view showing a fixing structure between a gear 1 and a rotating shaft 2 according to the first embodiment of the present invention. FIG. 2 is a front view showing a fixing structure between the gear 1 and the rotating shaft 2 of the present embodiment. FIG. 3 is a left side view showing a fixing structure of the gear 1 and the rotating shaft 2. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is an explanatory view showing the shape of the gear 1, FIG. 5 (a) is a front view, and FIG. 5 (b) is a cross-sectional view taken along line VV in FIG. 5 (a). 6A and 6B are explanatory views showing the shape of the rotating shaft 2. FIG. 6A is a plan view, FIG. 6B is a front view, and FIG. 6C is a left side view. FIG. 7 is an explanatory view showing a cross section in a state where the rotation shaft 2 of FIG. 6 has started to be inserted into the gear 1 of FIG.

  As shown in FIGS. 1 to 4, the gear 1 and the rotation shaft 2 of the present embodiment are fixed by fitting one end portion 2 a side of the rotation shaft 2 into the center hole 1 a of the gear 1. It is used for a rotation mechanism that performs a rotation operation about the center axis of the rotation.

  The gear 1 is made of resin and is processed into a shape shown in FIG. 5 by molding. The center hole 1a in a molding state before fitting the rotating shaft 2 penetrates in the axial direction (Z1-Z2 direction), and has a rotation restricting portion 1b shown in FIG. It is provided in a hole shape.

  The rotating shaft 2 is made of metal having higher rigidity than the gear 1, and is processed into the shape shown in FIG. As shown in FIG. 6, the rotating shaft 2 includes a cylindrical surface portion 21 having different axial diameters in the first region 21 a, the second region 21 c, and the third region 21 e when viewed in the axial direction from the one end 2 a, And a plane portion 22 parallel to the axial direction. The first region 21a and the second region 21c are connected by the first step portion 21b. The second region 21c and the third region 21e are connected by the second step portion 21d. As shown in FIG. 6C, the shaft diameter D21a of the first region 21a, the shaft diameter D21c of the second region 21c, and the shaft diameter D21e of the third region 21e in the cylindrical surface portion 21 are as follows. is there. That is, the shaft diameter D21a of the first region 21a is larger than the shaft diameter D21c of the second region 21c and the shaft diameter D21e of the third region 21e, and the second diameter is larger than the shaft diameter D21e of the third region 21e. The shaft diameter D21c of the region 21c is formed small. The flat surface portion 22 is a processed surface formed by, for example, processing the cylindrical surface portion 21 rotationally symmetrically and then cutting out a part along the YZ plane. In addition, in order to make the 1st area | region 21a, 2nd area | region 21c, and 3rd area | region 21e easy to understand, it has shown in figure so that the magnitude | size of an axial diameter may differ greatly, It is about several percent.

  The gear 1 and the rotating shaft 2 of this embodiment are integrated by the following fixing methods.

  As shown in FIG. 7, the rotary shaft 2 is inserted into the center hole 1a on the end face 1c side of the gear 1 from the one end 2a. In the gear 1, the center hole 1 a before press-fitting shown in FIG. 5B is provided with a dimension equivalent to the cross-sectional shape formed by the flat surface portion 22 of the rotating shaft 2 and the cylindrical surface portion 21 of the second region 21 c in FIG. 6. It has been. Since the rotating shaft 2 has higher rigidity than the gear 1, the rotating shaft 2 is press-fitted into the gear 1 while expanding the center hole 1a. Then, as shown in FIG. 4, the rotating shaft 2 is inserted until one end 2 a reaches the other end face 1 d of the gear 1.

  As a result, as shown in FIG. 4, in the gear 1, the abutting portion 11 a of the side surface 11 of the center hole 1 a abuts on the first region 21 a and the third region 21 e of the cylindrical surface portion 21 and the flat surface portion 22. ing. And the engaging part 11b of the side surface 11 of the center hole 1a is contact | abutting to the 2nd area | region 21c between the 1st step part 21b and the 2nd step part 21d. Further, the first step portion 21b and the second step portion 21d of the rotating shaft 2 are engaged with the engaging portion 11b of the center hole 1a. In addition, the engaging part 11b may be in a state having a slight gap without contacting the second region 21c.

  When the rotary shaft 2 is press-fitted, the rotation restricting portion 1 b of the gear 1 is in a state of being pressed against the flat portion 22 of the rotary shaft 2. Thereby, the gear 1 and the rotating shaft 2 are regulated so as to rotate integrally in the rotation direction.

  With respect to the axial direction, the first region 21a and the third region 21e of the cylindrical surface portion 21 and the contact portion 11a of the center hole 1a, and the first step portion 21b and the second step portion 21d The engagement of the center hole 1a with the engaging portion 11b makes it difficult for the gear 1 to come off the rotating shaft 2.

  Hereinafter, referring to FIG. 4 and FIGS. 8 to 10, the fixing structure between the gear 1 and the rotating shaft 2 of the present embodiment brings about a remarkable effect as compared with the comparative example conceivable from the conventional fixing structure. A supplementary explanation will be given. FIG. 8 is a cross-sectional view showing a fixing structure A of a comparative example. 9 is a cross-sectional view showing a fixing structure B of a comparative example different from FIG. 10 is a cross-sectional view showing a fixing structure C of a comparative example different from FIG.

  In the fixing structure A of the comparative example shown in FIG. 8, a groove A24 is formed in the press-fitted region A23 of the rotary shaft A2 in the same manner as the gear fixing structure described in Patent Document 1 described in the background art, and the engagement of the gear A1 is performed. Part A11b is configured to engage. The press-fitting region A23 of the rotation shaft A2 has a shaft diameter larger than the inner diameter of the center hole A1a before press-fitting, and is press-fitted while expanding the center hole A1a from one end face side to the other end face side of the gear A1. For this reason, when the strain in the region in contact with the press-fitting region A23 increases, the gear A1 is deformed by the strain, and the performance of the rotating mechanism is degraded. In order to suppress this distortion, the shaft diameter of the press-fitting region A23 of the rotary shaft A2 must be approximately 103% or less with respect to the inner diameter of the center hole A1a before press-fitting. The gear A1 can be easily removed from the rotary shaft A2 only by press-fitting with this shaft diameter, and the effect of retaining the engagement is insufficient even though the engaging portion A11b is engaged with the groove A24. Met.

  The fixing structure B of the comparative example shown in FIG. 9 is configured such that a press-fitting region B25 having a larger shaft diameter is added to the press-fitting region B23 of the rotating shaft B2 to strengthen the press-fitting into the center hole B1a of the gear B1. It is. The shaft diameter of the press-fitting region B25 was set to approximately 106% with respect to the inner diameter of the center hole B1a before press-fitting. By increasing the shaft diameter of the press-fitting region B25, the effect of engaging the engaging portion B11b of the gear B1 is added to the step between the press-fitting region B25 and the press-fitting region B23. Was insufficient.

  The fixing structure C of the comparative example shown in FIG. 10 is configured to further increase the press-fitting into the center hole C1a of the gear C1 by adding a press-fitting region C25 having a larger shaft diameter to the press-fitting region C23 of the rotating shaft C2. Is. The shaft diameter of the press-fitted region C25 was set to approximately 109% with respect to the inner diameter of the center hole C1a before press-fitting. By increasing the shaft diameter of the press-fitting region C25, an effect of engaging the engaging portion C11b of the gear C1 is added to the step between the press-fitting region C23 and the press-fitting region C25, so that the retaining strength of the gear C1 is greatly improved. I was able to. However, since the strain in the region in contact with the press-fitted region C25 is larger than that in the fixed structure B in FIG. 9, the gear C1 is deformed due to the strain and the performance of the rotating mechanism is deteriorated. did.

  Starting from the comparative example shown in FIG. 9 and FIG. 10, in order to achieve both the retaining strength and the strain, the axial diameter and axial dimension of the press-fitted region B23 (C23) and the press-fitted region B25 (C25) are set. Although we tried to optimize, these dimensions alone could not eliminate the trade-off relationship.

  The structure for fixing the gear 1 and the rotary shaft 2 according to the present embodiment includes a first region 21a, a second region 21c, and a third region 21e, and the first region 21a is a second region 21c and a second region 21c. The third region 21e has a larger shaft diameter, and the third region 21e has a larger shaft diameter than the second region 21c. The first step portion 21 b and the second step portion 21 d of the rotating shaft 2 are engaged with the engaging portion 11 b of the center hole 1 a of the gear 1. The axial diameter D21a of the first region 21a is 106% and the axial diameter D21c of the second region 21c is 100% with respect to the dimension before press-fitting of the central hole 1a (the axial diameter of the second region 21c and the central hole 1a). ) And the shaft diameter D21e of the third region 21e is 103%, so that both the retaining strength and the strain are compatible. That is, the gear 1 has a strain that is compressed in the radial direction, the strain in the region that contacts the third region 21e is approximately 3%, and the strain in the region that contacts the first region 21a is approximately 6%. Since the strain could be reduced, the performance deterioration of the rotating mechanism was suppressed. Further, the pulling force for pulling out the gear 1 was approximately 120 N, and a sufficient retaining strength was obtained. In the fixing structure A of the comparative example shown in FIG. 8, the shaft diameter of the press-fitting region A23 of the rotary shaft A2 has to be approximately 103% or less with respect to the inner diameter of the center hole A1a before press-fitting. If the shaft diameter D21e of the third region 21e is 104% or less with respect to the dimension before the press-fitting of the center hole 1a, the distortion of the gear 1 is reduced to the performance of the rotating mechanism. It was possible to make the size within an allowable range in which deterioration was suppressed.

  This result is considered as follows. The gear 1 not only contacts the third region 21e of the press-fitted rotating shaft 2 but also contacts the first region 21a having the maximum shaft diameter, so that the retaining strength of the gear 1 can be reduced to the first region. It can be enlarged by 21a. The rotating shaft 2 can increase the shaft diameter of the first region 21a with respect to the shaft diameter of the second region 21c, which is equal to the dimension of the center hole 1a before press-fitting. Thereby, since the difference in the shaft diameter between the first region 21a and the second region 21c is large, the step of the engaging portion 11b of the gear 1 that engages with the first step portion 21b is large, and the gear in the axial direction is large. It can be reliably prevented from coming off.

  Further, since the third region 21e and the first region 21a of the rotating shaft 2 are in a stable press-fitted state, the gear 1 is inclined even if the second region 21c having a small shaft diameter in the middle is wide. Or flare accuracy does not decrease. Further, since the second region 21c is not in the press-fitted state, it is considered that the strain caused by the press-fitting of the third region 21e and the first region 21a of the rotating shaft 2 is reduced.

  In the above range, the second region 21c has substantially the same dimensions as the dimensions before press-fitting the center hole 1a. In the gear 1, the center hole 1 a before press-fitting shown in FIG. 5B has a dimension equal to or less than the cross-sectional shape formed by the flat surface portion 22 of the rotating shaft 2 and the cylindrical surface portion 21 of the second region 21 c in FIG. 6. What is necessary is just to be provided. Note that if the shaft diameter D21c of the second region 21c is larger than the size of the center hole 1a before press-fitting, a press-fitted state occurs, and the strain in the region in contact with the first region 21a is not relaxed. The shaft diameter D21a of the region 21a cannot be made too large. The range in which both the retaining strength and the strain can be obtained is such that the shaft diameter D21a of the first region 21a is 106% or less with respect to the dimension before press-fitting of the center hole 1a, and the shaft diameter of the second region 21c. The shaft diameter D21a of the first region 21a is 104% to 106% with respect to D21c. At this time, the gear 1 has a strain that is compressed in the radial direction in a region that is in contact with the first region 21a and the third region 21e of the rotary shaft 2, and the strain in the region that is in contact with the third region 21e is It is 4% or less, and the strain of the region in contact with the first region 21a is 6% or less.

  In the gear 1 of the present embodiment, the center hole 1a has the same cross-sectional shape from the end face 1c side to the other end face 1d side, and the same press-fitted state even if the rotary shaft 2 is inserted from the other end face 1d side. Is obtained. That is, the gear 1 when fixing the rotating shaft 2 has no directionality. Therefore, workability is good because the gear 1 can be fixed without worrying about the direction.

  Hereinafter, the effect by having set it as this embodiment is demonstrated.

  The fixing structure of the gear 1 and the rotating shaft 2 according to the present embodiment includes a resin gear 1 provided with a center hole 1a and a rotating shaft 2 engaged with the center hole 1a. The rotary shaft 2 is made of a material having higher rigidity than that of the gear 1, and includes a flat portion 22 parallel to the axial direction, a first region 21a, a second region 21c, and a third region as viewed in the axial direction from the one end portion 2a. The cylindrical surface portion 21 having a different axial diameter in the region 21e, the first step portion 21b connected to the first region 21a and the second region 21c, and the second connected to the second region 21c and the third region 21e. And a step portion 21d. The cylindrical surface portion 21 is provided such that the first region 21a has a larger shaft diameter than the second region 21c and the third region 21e, and the second region 21c has a smaller shaft diameter than the third region 21e. ing. Further, the gear 1 includes a contact portion 11a in which the side surface 11 of the center hole 1a contacts at least the first region 21a and the third region 21e of the cylindrical surface portion 21 and the plane portion 22, and the first region 21a and the first region 21a. And an engaging portion 11b having an inner diameter smaller than the axial diameter of the third region 21e and engaging with the first step portion 21b.

  According to this configuration, the gear 1 not only contacts the third region 21e but also contacts the first region 21a having the maximum shaft diameter, so that the retaining strength of the gear 1 can be reduced to the first region 21a. To make it difficult to come off the rotary shaft 2. Furthermore, even if the second region 21c having a small shaft diameter in the middle is wide, the gear 1 is not inclined and the flare accuracy is not lowered.

  In the fixing structure of the gear 1 and the rotary shaft 2 according to the present embodiment, the rotary shaft 2 has a shaft diameter of 104% to 106% of the first region 21a with respect to the shaft diameter of the second region 21c. is there.

  According to this configuration, since the difference in shaft diameter between the first region 21a and the second region 21c is large, the step of the engaging portion 11b of the gear 1 that engages with the first step portion 21b is large, and the axial direction It is possible to reliably prevent the gear from falling out.

  Further, the gear 1 has a strain that is compressed in the radial direction in a region that is in contact with the first region 21a and the third region 21e of the rotary shaft 2, and a strain in a region that is in contact with the third region 21e is 4 %, And the strain in the region in contact with the first region 21a is 6% or less.

  According to this configuration, deformation of the gear 1 due to strain can be suppressed.

  In addition, the fixing method of the gear 1 and the rotating shaft 2 of the present embodiment is that the rotating shaft 2 having a rigidity higher than that of the gear 1 is press-fitted into the central hole 1a of the resin gear 1 and the rotating shaft 2 is attached. The rotating shaft 2 includes a plane portion 22 parallel to the axial direction, and a first region 21a, a second region 21c, and a third region 21e as viewed in the axial direction from the one end portion 2a. A cylindrical surface portion 21 having a different axial diameter, a first step portion 21b connected to the first region 21a and the second region 21c, and a second step portion 21d connected to the second region 21c and the third region 21e. And are provided. The cylindrical surface portion 21 is provided such that the first region 21a has a larger shaft diameter than the second region 21c and the third region 21e, and the second region 21c has a smaller shaft diameter than the third region 21e. ing. Further, the gear 1 is provided in a cross-sectional direction perpendicular to the axial direction so that the center hole 1a before press-fitting has a dimension equal to or smaller than the cross-sectional shape formed by the flat surface portion 22 and the cylindrical surface portion 21 of the second region 21c. At least a part of each of the first region 21a, the second region 21c, and the third region 21e is press-fitted into the central hole 1a of the first region by inserting the rotary shaft 2 from the one end 2a. .

  According to this configuration, not only the third region 21e is press-fitted into the center hole 1a of the gear 1, but also the first region 21a having the maximum shaft diameter is press-fitted. The retaining strength can be increased by the first region 21 a to make it difficult for the gear 1 to come off the rotating shaft 2.

  Moreover, in the fixing method of the gear 1 and the rotating shaft 2 of this embodiment, the rotating shaft 2 has a shaft diameter of the first region 21a of 106% or less with respect to the dimension before press-fitting of the center hole 1a. The shaft diameter of the first region 21a is 104% or more with respect to the shaft diameter of the second region 21c.

  According to this configuration, deformation of the gear 1 due to strain can be suppressed.

[Second Embodiment]
FIG. 11 is a partial perspective view showing the recording apparatus 100 according to the second embodiment of the present invention. In FIG. 11, parts other than those relating to the configuration of the present invention are omitted.

  As shown in FIG. 11, the recording apparatus 100 according to the present embodiment includes a paper conveyance driving unit 30 that sends the paper 80 and a recording unit 40 that records on the paper 80 sent by the paper conveyance driving unit 30. ing. The paper conveyance drive unit 30 transmits power to the stepping motor 33 controlled by a control unit (not shown), the paper feed roller 38 disposed so as to be in contact with the paper 80, and the paper feed roller 38 from the stepping motor 33. And a rotation mechanism. The recording means 40 has a print head 46 controlled by a control unit (not shown), and records on the paper 80 by printing. The recording means 40 is not limited to the present embodiment. For example, the recording means 40 is for recording data in an array in which holes are formed in the paper 80 and with or without holes, or for other recording methods. Also good.

  In the present embodiment, the rotation mechanism used for the paper conveyance drive unit 30 includes the fixed structure of the gear 1 and the rotation shaft 2 of the first embodiment, and the rotation can be controlled by the stepping motor 33. By providing the fixing structure of the gear 1 and the rotating shaft 2 according to the first embodiment, the strain at the time of fixing the gear 1 and the rotating shaft 2 can be reduced, and the performance deterioration of the rotating mechanism is suppressed. At the same time, a sufficient retaining strength in securing the gear 1 and the rotating shaft 2 is obtained. For this reason, even if an impact is applied to the recording apparatus 100 and a force is applied in the direction in which the gear 1 comes off the rotary shaft 2, the gear 1 does not fall off or become loose.

  Hereinafter, the effect by having set it as this embodiment is demonstrated.

  The recording apparatus 100 according to the present embodiment includes a sheet conveyance driving unit 30 that sends a sheet 80 and a recording unit 40 that records on the sheet 80 sent by the sheet conveyance driving unit 30. The paper conveyance drive unit 30 includes a gear 1 and a rotation shaft 2 that can be controlled to rotate, and includes a fixing structure for the gear 1 and the rotation shaft 2 according to the first embodiment.

  According to this configuration, it is possible to realize the recording apparatus 100 in which the gear 1 is difficult to come off and the paper feeding accuracy is high.

  As described above, the fixing structure and fixing method between the gear 1 and the rotating shaft 2 of the first embodiment of the present invention and the recording apparatus 100 of the second embodiment have been specifically described. The present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. For example, the present invention can be modified as follows, and these also belong to the technical scope of the present invention.

  (1) In the present embodiment, the rotating shaft 2 is made of a metal having higher rigidity than the gear 1, but may be changed to a material having higher rigidity than the metal.

  (2) In the present embodiment, the first step portion 21b and the second step portion 21d of the rotating shaft 2 are illustrated as shapes that are part of a conical surface, but are not limited thereto. For example, the shape which becomes a part of spherical surface, or a concave curved surface shape may be sufficient. Moreover, the shape used as a part of circular ring perpendicular | vertical to an axial direction may be sufficient.

  (3) In the present embodiment, the rotation restricting portion 1b of the gear 1 and the flat portion 22 of the rotating shaft 2 are arranged at one place, but may be arranged at a plurality of places. For example, it can be arranged at two positions symmetrical from the central axis.

1 gear 1a center hole 1b rotation restricting portion 1c end surface 1d end surface 2 rotating shaft 2a one end portion 11 side surface 11a abutting portion 11b engaging portion 21 cylindrical surface portion 21a first region 21b first step portion 21c second region 21d second Step part 21e 3rd area 22 Plane part 30 Paper conveyance drive part 33 Stepping motor 38 Paper feed roller 40 Recording means 46 Print head 80 Paper 100 Recording device A1 Gear A1a Center hole A2 Rotating shaft A11b Engagement part A23 Press fit area A24 Groove B1 Gear B1a Center hole B2 Rotating shaft B11b Engagement part B23 Press fit area B25 Press fit area C1 Gear C1a Center hole C2 Rotation shaft C11b Engagement part C23 Press fit area C25 Press fit area D21a Shaft diameter D21c Shaft diameter D21e Shaft diameter

Claims (6)

A resin gear provided with a center hole, and a rotation shaft engaged with the center hole,
The rotating shaft is made of a material having rigidity higher than that of the gear, and is different in a flat portion parallel to the axial direction and in the first region, the second region, and the third region as viewed in the axial direction from one end portion. A cylindrical surface portion having a diameter, a first step portion connected to the first region and the second region, and a second step portion connected to the second region and the third region. ,
The cylindrical surface portion has a larger shaft diameter of the first region than the second region and the third region, and a smaller shaft diameter of the second region than the third region,
In the gear, the side surface of the central hole has at least the first region and the third region of the cylindrical surface portion, a contact portion that contacts the flat surface portion, the first region and the third region. An engagement portion that has an inner diameter smaller than that of the first step portion and that engages with the first step portion.   2. The gear according to claim 1, wherein the rotation shaft has a shaft diameter of 104% to 106% with respect to a shaft diameter of the second region. Fixed structure.   The gear has a strain that is compressed in a radial direction in a region in contact with the first region and the third region of the rotation shaft, and the strain in the region in contact with the third region is 4%. The gear and rotating shaft fixing structure according to claim 1 or 2, wherein the strain in the region that is in contact with the first region is 6% or less. A sheet conveying drive unit for sending the sheet, and a recording unit for recording on the sheet sent by the sheet conveying drive unit,
The said paper conveyance drive part has a gear and a rotating shaft which can be rotationally controlled, and is provided with the fixing structure of the gear and rotating shaft in any one of Claim 1 thru | or 3. Recording device. A method of fixing the rotating shaft and the gear to be attached by press-fitting a rotating shaft having higher rigidity than the gear into the center hole of the resin gear,
The rotating shaft includes a plane portion parallel to the axial direction, a cylindrical surface portion having different axial diameters in the first region, the second region, and the third region as viewed in the axial direction from one end portion, and the first A first step portion connected to the second region and the second region, and a second step portion connected to the second region and the third region,
The cylindrical surface portion has a larger shaft diameter of the first region than the second region and the third region, and a smaller shaft diameter of the second region than the third region,
In the cross-sectional direction perpendicular to the axial direction, the gear is provided with a size equal to or less than the cross-sectional shape formed by the central hole before the press-fitting between the flat surface portion and the cylindrical surface portion of the second region,
The rotation shaft is inserted into the central hole of the gear from the one end, and at least a part of each of the first region, the second region, and the third region is press-fitted. A fixing method between a gear and a rotating shaft. The rotation shaft has a shaft diameter of 106% or less of the first region with respect to the dimension before press-fitting of the center hole,
The method for fixing a gear and a rotary shaft according to claim 5, wherein the shaft diameter of the first region is 104% or more with respect to the shaft diameter of the second region.