WO2020116371A1

WO2020116371A1 - Geared shaft production method, and drive device

Info

Publication number: WO2020116371A1
Application number: PCT/JP2019/046945
Authority: WO
Inventors: 清水　猛; 樹哉岸野; 小川　隆雄
Original assignee: 日本電産株式会社
Priority date: 2018-12-05
Filing date: 2019-12-02
Publication date: 2020-06-11

Abstract

In the present invention, produced is a geared shaft provided with a gear that has excellent mechanical strength and shape stability. This geared shaft production method is for producing a geared shaft that has a gear having a hole that penetrates through in the axial direction, and a shaft that is fixed to the gear in a state where an end has been inserted into the hole. This production method comprises: a step for melting a resin composition that contains a crystalline resin and a filler; a step for supplying the molten-state resin composition to a shaping mold set to a temperature 5°C to 25°C lower than the glass transition temperature of the crystalline resin, and obtaining a molding that has a shape corresponding to the gear; a step for press-fitting the molding into the end of the shaft, and assembling the molding and the shaft; and a step for heat-treating the molding at a higher temperature than the crystallization temperature of the crystalline resin, and obtaining the gear fixed to the shaft.

Description

Gear shaft manufacturing method and drive device

The present invention relates to a method for manufacturing a geared shaft and a drive device.

BACKGROUND ART Conventionally, a structure in which a gear is fixed to a lead screw has been used as a mechanism for converting rotary motion into linear motion (see, for example, Patent Document 1). In the case of manufacturing such a structure, the lead screw may be made of a metal material, the gear may be made of a resin material, and the gear may be press-fitted to the end portion of the lead screw to be assembled. Further, a crystalline resin may be used as the resin material in order to increase the mechanical strength of the gear. In this case, if the crystalline resin is crystallized before the gear is press-fitted into the lead screw, the elongation rate of the obtained gear decreases. Therefore, when such a gear is press-fitted into the lead screw, a defect such as creep is likely to occur in the gear.

Japanese Patent Publication: Japanese Patent Laid-Open No. 2006-154373

The present invention has been made in view of the above problems, and an object of the present invention is to provide a geared shaft that is less likely to cause defects in gears and that has excellent durability, and a geared shaft that is manufactured by the method for manufacturing a geared shaft. It is to provide a drive device including.

An exemplary invention of the present application is a method for manufacturing a geared shaft having a gear having a hole penetrating in the axial direction and a shaft fixed to the gear with an end inserted in the hole. A step of melting a resin composition containing a crystalline resin and a filler, and a molding die in which the resin composition in the molten state is set at a temperature 5 to 25° C. lower than the glass transition temperature of the crystalline resin. Supplying the molded body having a shape corresponding to the gear, assembling the molded body and the shaft by press-fitting the molded body into the end portion of the shaft, and A heat treatment at a temperature higher than the crystallization temperature of the crystalline resin to obtain the gear fixed to the shaft. ‥

Another exemplary invention of the present application is to provide a geared shaft obtained by the method for manufacturing a geared shaft, a drive gear arranged to mesh with the gear of the geared shaft, and the drive gear. It is a drive device having a drive unit for driving.

According to the exemplary invention of the present application, it is possible to manufacture a geared shaft including a gear having excellent mechanical strength and shape stability.

FIG. 1 is a side view showing a state in which a combiner is projected from a case main body in a head-up display in which a geared shaft manufactured by the method for manufacturing a geared shaft of the present invention is incorporated. FIG. 2 is a perspective view of a main part of FIG. FIG. 3 is a perspective view in which the frame and unit case of FIG. 2 are omitted. FIG. 4 is a perspective view of an essential part showing a state in which the combiner of FIG. 1 is housed in the case body. FIG. 5 is a side view of FIG. FIG. 6 is a perspective view of the evaluation device.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, a pop-up storage type head-up display (hereinafter referred to as “HUD”) 1 is fixed to a case body 1 a, a frame 2 fixed inside the case body 1 a, and a frame 2. The two guide shafts 3 are provided. The case body 1a has a top plate 1b formed with an opening through which the combiner 13 of the unit case 4 described later can pass. The combiner 13 can project to the outside of the case body 1a by passing through this opening. ‥

As shown in FIG. 2, the frame 2 has a wall plate 2a arranged along the vertical direction, and an upper flange 2b and a lower flange 2c formed at the upper and lower ends of the wall plate 2a and bent in the horizontal direction. It is composed of a plate-shaped member. Two guide shafts 3 are provided at intervals in the horizontal direction between the upper flange 2b and the lower flange 2c. ‥

Further, the HUD 1 includes a unit case 4 that is vertically movable along each guide shaft 3, and a lead screw 5 that is installed between the two guide shafts 3 and that penetrates the unit case 4. .. The unit case 4 has a box shape with an open top surface. The upper and lower ends of the lead screw 5 are rotatably supported by the upper and

lower flanges

2b and 2c, respectively. ‥

As shown in FIGS. 2 and 3, the HUD 1 includes a stepping motor (first motor) 6 fixed to the lower surface of the lower flange 2c, a gear 7 fixed to the output shaft of the stepping motor 6, and a lead screw. A gear 8 fixed to the lower end of the lead screw 5 and a nut 9 meshing with the lead screw 5 are provided. Each of the gear 7 and the gear 8 is a spur gear, the gear 7 is a small gear, and the gear 8 is a large gear. The gear 7 and the gear 8 mesh with each other. The nut 9 is fixed to the unit case 4. ‥

Then, the stepping motor 6 operates to rotate the gear 7. This rotational force is transmitted to the gear 8 and the gear 8 can be rotated together with the lead screw 5. As a result, the nut 9 can move along the lead screw 5 while meshing with the lead screw 5. By moving the nut 9 in the upward direction, the unit case 4 fixed to the nut 9 can rise in the case body 1a as shown in FIGS. 2 and 3. Further, when the gear 7 is rotated in the opposite direction to the above by the operation of the stepping motor 6, the unit case 4 is moved downward as shown in FIGS. 4 and 5 by the downward movement of the nut 9. It can descend in 1a. That is, at least the lead screw 5 to which the gear 8 is fixed, the gear (driving gear) 7 arranged so as to mesh with the gear 9, and the stepping motor (driving unit) 6 that drives the gear 7 of the present invention. A drive unit is configured. ‥

As shown in FIG. 3, the HUD 1 includes a rotary shaft 10 rotatably supported in a unit case 4, a base portion 11 fixed to a central portion in the longitudinal direction of the rotary shaft 10, and a base portion 11. The combiner holder 12 provided and the combiner 13 attached to the combiner holder 12 are provided. ‥

The rotary shaft 10 is arranged in the horizontal direction and can rotate around its axis. The base portion 11 is a portion having a diameter larger than that of the rotating shaft 10, and a screw 11a is formed on a lower half of the periphery thereof. Further, a flat plate-like combiner holder 12 is provided in parallel with the rotating shaft 10 on the outer periphery of the upper portion of the base 11. The upper portion of the combiner holder 12 projects from the upper opening of the unit case 4. The lower end of the combiner 13 is attached to this protruding portion. The combiner 13 has a plate shape and is arranged along the vertical direction. ‥

A projection unit (not shown) for projecting an image toward the combiner 13 is arranged in the case body 1a, adjacent to the elevating regions of the frame 2 and the unit case 4. ‥

As shown in FIG. 3, the HUD 1 includes a pinion gear 14 rotatably provided in the unit case 4, a helical gear 15 integrally formed with the pinion gear 14, and a tilt stepping motor (not shown) mounted in the unit case 4. (Second motor) 16 and a worm gear 17 fixed to the output shaft of the stepping motor 16. In the HUD 1, the screw 11 a of the base 11, the pinion gear 14, the helical gear 15, and the worm gear 17 constitute a rotating mechanism for rotating the rotating shaft 10. ‥

The pinion gear 14 is provided with its axis parallel to the rotary shaft 10 and meshes with the screw 11a. A helical gear 15 having a diameter larger than that of the pinion gear 14 is arranged on one end side of the pinion gear 14. The pinion gear 14 and the helical gear 15 are arranged coaxially and can rotate in synchronization. The output shaft of the tilt stepping motor 16 is arranged along the vertical direction. The worm gear 17 is fixed to the output shaft of the stepping motor 16, and can be rotated about the output shaft by the operation of the stepping motor 16. The worm gear 17 meshes with the helical gear 15. ‥

In the HUD 1 having the above configuration, as described above, when the lead screw 5 is rotated by the operation of the stepping motor 6, the unit case 4 together with the nut 9 meshing with the lead screw 5 can be raised along the guide shaft 3. .. As a result, as shown in FIGS. 1 to 3, the combiner 13 provided on the upper portion of the unit case 4 can pass through the opening of the case body 1a and project to the outside of the case body 1a. Then, when the tilt stepping motor 16 is operated in this protruding state, the worm gear 17 rotates, and the rotational force thereof is transmitted to the helical gear 15. As a result, the helical gear 15 can be rotated together with the pinion gear 14. Further, the rotational force of the pinion gear 14 is transmitted to the rotary shaft 10 via the screw 11a. As a result, the rotary shaft 10 can be rotated together with the combiner 13, and thus the tilt angle of the combiner 13 with respect to the projection unit can be adjusted. The image (image) from the projection unit is accurately projected on the combiner 13 whose tilt angle is adjusted. ‥

After using the combiner 13, the tilting stepping motor 16 is operated to return the combiner 13 to the upright state, that is, the tilt angle. Then, the stepping motor 5 is operated and the lead screw 5 is rotated in the opposite direction to the above, whereby the unit case 4 is lowered along the guide shaft 3. Thereby, as shown in FIGS. 4 and 5, the combiner 13 can be stored in the case body 1a. A hole penetrating in the axial direction is formed in the gear 8, and the gear 8 is fixed to the lead screw 5 with the end portion of the lead screw 5 being inserted into the hole. As a result, the geared shaft 20 in which the lead screw 5 and the gear 8 are integrated is configured. ‥

<Method of Manufacturing Geared Shaft> In the HUD 1 having the above-described configuration, the geared shaft 20 is manufactured by the method of manufacturing the geared shaft of the present invention. The geared shaft manufacturing method of the present invention is a method of manufacturing a geared shaft 20 having a lead screw (shaft) 5 and a gear 8 fixed to an end thereof. The geared shaft manufacturing method according to the present embodiment includes [1] a first step of preparing a resin composition containing a crystalline resin and a filler, and [2] a second step of melting the resin composition. And [3] the molten resin composition is supplied to a molding die set at a temperature about 5 to 25° C. lower than the glass transition temperature of the crystalline resin, and the molding has a shape corresponding to the gear 8 to be manufactured. A step of obtaining a body, [4] a fourth step of assembling the molded body and the lead screw 5 by press-fitting the molded body 8 into the end of the lead screw 5, and [5] molding a crystalline resin. And heat treatment at a temperature higher than the crystallization temperature to obtain the gear 8 fixed to the lead screw 5. ‥

[1] First step First, a resin composition containing a crystalline resin and a filler is prepared. Here, the crystalline resin refers to a thermoplastic resin having a melting peak when a differential scanning calorimetry (DSC) based on JIS K 7121:2012 (Plastic transition temperature measuring method) is performed. Examples of the crystalline resin include polyamide, polyolefin, polyester, polyether, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyacetal (POM), polyimide, and fluoropolymer. Incidentally. These resins may be used alone or in combination of two or more. Of these, polyamide is preferable as the crystalline resin. The use of polyamide can improve the mechanical strength, rigidity and wear resistance of the gear.・

Polyamides are generally classified into aliphatic polyamides (non-aromatic polyamides), semi-aromatic polyamides and wholly aromatic polyamides, but semi-aromatic polyamides are preferred. Semi-aromatic polyamides are preferable because they are easily melted and easily crystallized. The semi-aromatic polyamide is a copolymer of dicarboxylic acid and diamine, one of which has an aromatic group and the other has an aliphatic group.

Examples of the aliphatic dicarboxylic acid include HOOC-(CH ₂ ) _n- COOH (n is 0 to 12), dimethylmalonic acid, 3,3-diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipine Acids, chain-like aliphatic dicarboxylic acids such as trimethyladipic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid And alicyclic dicarboxylic acids such as cyclodecane dicarboxylic acid. On the other hand, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid and 4,4′-biphenyl. Examples thereof include dicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid and diphenylsulfone-4,4'-dicarboxylic acid.

Examples of the aliphatic diamine include linear aliphatic diamines such as NH ₂ —(CH ₂ ) _m —NH ₂ (m is 0 to 12), 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3- Methyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 1, Branching such as 3-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine Alicyclic diamine such as aliphatic diamine, cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornenedimethylamine and tricyclodecanedimethyldiamine. On the other hand, as the aromatic diamine, for example, p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 4 , 4'-diaminodiphenyl ether and the like.

Examples of the semi-aromatic polyamide include polyamide MXD6 (PAMXD6), polyamide 9T (PA9T), polyamide 4T (PA4T), polyamide 6T (PA6T), polyamide 10T (PA10T), and the like. Examples of other polyamides include polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12) polyamide 66 (PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 410 (PA410). Etc. ‥

Examples of the polyolefin include polyethylene (PE) and polypropylene (PP). Examples of polyesters include polyethylene terephthalate (PET), polybutadiene terephthalate (PBT), polylactic acid (PLA), and the like. Examples of the polyether include polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), polyaryletherketone (PAEK), and the like. The melting point of the crystalline resin depends on its type, but is preferably about 165 to 390°C, more preferably about 175 to 375°C, and even more preferably about 185 to 360°C. .. ‥

The filler is mixed with the crystalline resin for the purpose of improving the moldability and releasability of the resin composition, or the durability (mechanical strength, rigidity, wear resistance) of the obtained gear. It is a component. Therefore, the filler is appropriately selected depending on the purpose and is not particularly limited. There are inorganic fillers and organic fillers as the fillers, but it is preferable to use the inorganic fillers for the purpose described above. Examples of the inorganic fillers include fibrous inorganic fillers, particle (powder) inorganic fillers, non-fibrous inorganic fillers such as flaky inorganic fillers, and the like. ‥

Examples of the fibrous inorganic filler include glass fiber, carbon fiber, asbestos fiber, inorganic whiskers (potassium titanate fiber, zinc oxide fiber, magnesium oxide fiber, aluminum oxide fiber, calcium sulfate fiber, silicon carbide fiber, silicon nitride fiber). , Silicon nitride fibers, mullite fibers, magnesium borate fibers, titanium boride fibers, etc.) and the like. Examples of the particulate inorganic filler include silica powder, quartz powder, glass beads, kaolin, clay, diatomaceous earth, wollastonite and the like. Examples of the plate-like inorganic filler include mica, talc, various metal pieces, and the like. ‥

These inorganic fillers are appropriately selected and used according to the size of the gear. For example, when manufacturing a micro gear having a module of 0.2 mm or less, preferably inorganic whiskers are used, and more preferably potassium titanate fibers are used. The inorganic whisker has an aspect ratio of 10 or more, but its average fiber length is almost equal to the diameter of glass fiber, carbon fiber, etc., and has an extremely fine shape. For this reason, when manufacturing a micro gear having a module of 0.2 mm or less, it is possible to improve characteristics such as mechanical strength of the gear, and when the resin composition is molded, protrusions are formed on the gate portion of the molded body. Are difficult to form (that is, the occurrence of defects such as gate breakage is prevented and the moldability of the gear is improved). Therefore, when manufacturing a micro gear having a module of 0.2 mm or less, it is preferable to use a resin composition containing polyamide and potassium titanate fiber. ‥

The amount of the filler contained in the resin composition is not particularly limited, but is preferably about 10 to 40% by mass, more preferably about 20 to 30% by mass. When the resin composition containing the filler in such an amount is used, the effect of improving the characteristics of the obtained gear and the effect of improving the moldability of the resin composition are exhibited in a well-balanced manner. A resin composition is obtained by mixing these crystalline resins and a filler. Various mixers such as a blender, a kneader, a roll, and an extruder can be used for this mixing. [2] Second step Next, the obtained resin composition is melted by heating it to a temperature higher than the melting point of the crystalline resin. The heating temperature is preferably about 5 to 20° C. higher than the melting point of the binder resin, and more preferably about 5 to 15° C. higher. ‥

[3] Third step Next, the resin composition in a molten state is supplied to a molding die by, for example, an injection molding method to obtain a molded body having a shape corresponding to the gear to be manufactured. The present invention is characterized in that the temperature of the molding die is set to a predetermined temperature. Specifically, the temperature of the mold is set to a temperature lower by about 5 to 25° C. than the glass transition temperature (Tg) of the crystalline resin. Conventionally, when forming a molded product containing a crystalline resin, in order to promote crystallization of the crystalline resin, the temperature of the mold is slightly lower than the melting point of the binder resin (much higher than the Tg of the crystalline resin. High temperature). In this case, according to the studies by the present inventors, the resin composition is likely to be stretched, resulting in defective gate disconnection, resulting in a phenomenon in which unnecessary protrusions are formed on the molded body, and the edge of the molded body. It was also found that the shape of the part (particularly, the shape of the edge of the tooth tip) becomes unstable. Further, since the temperature is relatively high (about 130 to 150° C.), it takes time (about 30 to 40 seconds) until the resin composition is solidified, including the crystallization time of the crystallization resin. It took a long time to mold the molded body. ‥

Therefore, in the present invention, the temperature of the mold is set to a temperature lower by about 5 to 25° C. than the glass transition temperature (Tg) of the crystalline resin. Since the preset temperature is sufficiently lower than the preset temperature of the conventional mold, when the resin composition is supplied to the mold, the resin composition is rapidly solidified into a molded body. For this reason, the resin composition is less likely to expand, the gate breakage is good, and the shape (contour shape) of the edge portion of the molded body is also stabilized. Further, the releasability of the molded body from the molding die is also enhanced. From the above, according to the present invention, the time required for forming the molded body can be sufficiently shortened (about 10 to 15 seconds) as compared with the conventional case. Therefore, the yield in the production of the molded body can be improved, and the number of installed facilities for manufacturing the molded body can be significantly reduced. The mold temperature to be set may be a temperature about 5 to 25° C. lower than the Tg of the crystalline resin, but a temperature about 10 to 20° C. is more preferable. By setting the molding die at such a temperature, the above effect can be further improved. At this point, the crystallization of the crystallized resin has not substantially progressed. ‥

[4] Fourth step Next, the molded body is pressed into the end portion of the lead screw 5 to assemble the molded body and the lead screw 5. At this time, since the crystallization of the crystalline resin has not substantially progressed, the molded body can extend to some extent. Therefore, the end portion of the lead screw 5 can be easily inserted into the hole of the molded body, and the molded body is less likely to have defects such as creep. In addition, as a constituent material of the lead screw (shaft) 5, for example, a metal material, a ceramic material, a resin material having a high hardness, and the like can be cited. ‥

[5] Fifth Step Next, the molded body is heat-treated (annealed) at a temperature higher than the crystallization temperature of the crystalline resin to obtain the gear 8 fixed to the lead screw 5. At this time, as a result of crystallization of the crystalline resin in the molded body, the crystallinity of the molded body increases. Here, the crystallization temperature refers to an exothermic peak temperature that accompanies crystallization acceleration of the crystallized resin when the differential scanning calorimetry is performed on the crystalline resin under a temperature rising condition of 10° C./min. The temperature of the heat treatment may be higher than the crystallization temperature of the crystalline resin, but is 5 to 25° C. higher than the maximum temperature (hereinafter, also referred to as “actual use temperature”) when the Kia is actually used. The temperature is preferably, and more preferably about 10 to 20° C. higher than the actual use temperature. By performing the heat treatment at such a temperature, it is possible to ensure dimensional stability when the gear is used. In the case of the gear 8 used for the HUD 1 (in the vicinity of the stepping motor 6), its actual operating temperature is preferably about 110 to 140°C, more preferably about 120 to 130°C. ‥

Examples of the method of this heat treatment include a method of heating with a heater in a heating furnace, a method of irradiating infrared rays, a method of blowing hot air, and the like. The heating furnace may be a batch furnace or a continuous furnace. The pressure of the atmosphere of the heat treatment may be any of reduced pressure, normal pressure and increased pressure. The heat treatment time is not particularly limited, but is preferably about 30 to 120 seconds, more preferably about 45 to 100 seconds. The geared shaft 20 is manufactured through the above steps. ‥

By the heat treatment of the fifth step [5], the molded body slightly contracts, so that the gear 8 is firmly fixed to the lead screw 5. Further, prior to the fourth step [4] (step of assembling the molded body and the lead screw 5), a step of forming a retaining portion for preventing the gear 8 from coming off may be provided on the lead screw 5. . The step of forming the retaining portion is, for example, a process of forming irregularities on the outer peripheral surface of the lead screw 5 at a position where a gear is fixed (knurling), and a shape of the end portion of the lead screw 5 whose diameter is directed toward the tip. It can be performed for increasing processing (taper processing) and the like. As a result, the inner peripheral surface of the gear 8 bites into the unevenness of the outer peripheral surface of the lead screw 5, or the movement of the gear 8 along the axial direction of the lead screw 5 is restricted, and the gear 8 is prevented from moving. It will be fixed more firmly against. The shape of the unevenness is, for example, a groove formed along the circumferential direction of the shaft, a spiral groove formed inclined with respect to the axial direction, or formed along the circumferential direction and the axial direction of the shaft. Examples include mesh-shaped grooves.

The module of the gear 8 to be manufactured is not particularly limited, but is preferably 0.2 mm or less, more preferably about 0.1 to 0.2 mm. Even such a minute gear can be manufactured accurately and in a short time (high yield) by the method for manufacturing a shaft with a gear according to the present invention. In addition, since the obtained resin has the crystalline resin sufficiently crystallized therein, the gear has excellent properties such as mechanical strength, rigidity, and abrasion resistance, and high shape stability. Further, it is preferable that the micro gear has a reference circle pitch diameter of about 1.2 to 1.7 mm, a number of teeth of about 8 to 18 and a tooth thickness of about 0.15 to 0.32 mm. In particular, the gear 8 of the present embodiment is disposed in the vicinity of the stepping motor 6 and is easily affected by the heat generated by the stepping motor 6, so that it should be manufactured using a resin composition containing a semi-aromatic polyimide. Is preferred.

The method for manufacturing the geared shaft and the driving device according to the present invention have been described above based on the preferred embodiments, but the present invention is not limited thereto. For example, the shaft is not limited to the lead screw and may be a simple shaft member that supports the gear. Further, the geared shaft obtained by the method for producing a geared shaft of the present invention is, in addition to parts for industrial machines such as small cameras and robot hands, parts for automobiles, parts for bicycles, parts for railway vehicles, ships Parts, parts for aircraft, parts for transportation equipment such as parts for space transportation equipment, parts for personal computers, parts for electronic equipment such as parts for mobile terminals, parts for electric equipment such as refrigerators, washing machines, and air conditioners. , Parts for plants, parts for watches, etc.

Next, examples of the present invention will be described. 1. Production of Lead Screw with Gear (Example 1) [A] First, a semi-aromatic polyamide (PA9T) as a crystalline resin and potassium titanate fiber as an inorganic whisker were mixed with a blender to obtain a resin composition. .. The Tg of the aromatic polyamide was about 100° C., and the amount of potassium titanate fiber in the resin composition was 30% by mass. [B] Next, this resin composition was supplied to a mold set to about 80° C. to obtain a molded body having a shape corresponding to the gear to be manufactured. After confirming that the molded body was solidified, 11 minutes after the resin composition was supplied to the molding die, the molded body was taken out from the molding die. ‥

[C] Next, the obtained molded body was pressed into the end portion of the lead screw shown in FIG. 3 and the like to assemble the molded body and the lead screw. [D] Next, the molded body together with the lead screw was heat-treated in a heating furnace at 150° C. for 60 seconds to obtain a lead screw with a gear. The target gear had a reference circle pitch diameter of 1.3 mm, a module of 0.2 mm, 14 teeth, and a tooth thickness of 0.4 mm. ‥

(Comparative Example 1) The same as Example 1 except that the molded body was heat-treated in the same manner as in the above step [D] to obtain a gear without being pressed into the lead screw, and then was pressed into the end portion of the lead screw. Then, a lead screw with a gear was obtained. ‥

2. Evaluation Using the lead screw with a gear thus obtained, an evaluation device as shown in FIG. 6 was assembled. Then, the other end of the string having a weight of 200 g attached to one end was fixed to the elevating block 90 containing the nut 9 of the evaluation device, and the elevating operation of the elevating block 90 was repeated. As a result, in the evaluation device using the gear of Example 1, the lifting operation could be performed 300,000 times without any problem. On the other hand, in the evaluation device using the gear of Comparative Example 1, the gear became idle after the lifting operation of 150,000 times. The evaluation device was disassembled, and the gear had creep and the gear was broken.

1... Pop-up storage type head-up display (HUD), 1a... Case body, 1b... Top plate, 2... Frame, 2a... Wall plate, 2b... Upper flange, 2c... Lower flange, 3... Guide shaft, 4... Unit Case, 5... Lead screw, 6... Stepping motor (first motor), 7... Gear, 8... Gear, 9... Nut, 10... Rotating shaft, 11... Base portion, 11a... Screw, 12... Combiner holder, 13... Combiner, 14... Pinion gear, 15... Helical gear, 16... Tilt stepping motor (second motor), 17... Worm gear, 20... Geared shaft, 90... Lift block.

Claims

A method for producing a geared shaft having a gear having a hole penetrating in the axial direction and a shaft fixed to the gear with an end portion inserted in the hole, comprising a crystalline resin and a filler. And a step of melting the resin composition containing the above, and supplying the molten resin composition to a molding die set to a temperature 5 to 25° C. lower than the glass transition temperature of the crystalline resin to correspond to the gear. To obtain a molded body having a shape, a step of press-fitting the molded body into the end portion of the shaft to assemble the molded body and the shaft, and the molded body to crystallize the crystalline resin. A heat treatment at a temperature higher than the temperature to obtain the gear fixed to the shaft.
The method for manufacturing a geared shaft according to claim 1, wherein the temperature of the heat treatment is a temperature higher by 5 to 25° C. or more than the maximum temperature when the gear is actually used.
The method for producing a geared shaft according to claim 1 or 2, wherein the amount of the filler contained in the resin composition is 10 to 40% by mass.
The method for manufacturing a geared shaft according to any one of claims 1 to 3, wherein the gear module has a size of 0.2 mm or less.
The method for manufacturing a geared shaft according to claim 4, wherein the filler is an inorganic whisker.
The method for manufacturing a geared shaft according to claim 5, wherein the inorganic whiskers are potassium titanate fibers.
7. The method for manufacturing a geared shaft according to claim 1, wherein the crystalline resin is polyamide.
The method for manufacturing a geared shaft according to claim 7, wherein the polyamide is a semi-aromatic polyamide.
The gear with a gear according to any one of claims 1 to 8, further comprising a step of forming a retaining portion for preventing the gear from coming off on the shaft prior to the step of assembling the molded body and the shaft. Shaft manufacturing method.
The method for manufacturing a geared shaft according to any one of claims 1 to 9, wherein the shaft is a lead screw.
A geared shaft obtained by the method for manufacturing a geared shaft according to any one of claims 1 to 10, a drive gear arranged to mesh with the gear of the geared shaft, and the drive gear. A drive device having a drive unit for driving.