JP2530274B2 - Manufacturing method of multi-stage helical gear with sintered metal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multi-stage helical gear made of sintered metal, and an object thereof is to provide a preferable method for producing a composite helical gear made of sintered metal easily and at low cost.

[0002] A compound helical gear has been conventionally used in various ways as a member for obtaining efficient rotational force transmission and other operations due to its compact structure, and various proposals have been made regarding its manufacture, but mass production and low cost As a method to obtain, it is usual to use a resin molding or a powder molding sintered metal body, and in particular, under a use condition where strength and heat resistance are required, a solid metal material is cut and molded,
Alternatively, it is essential to use sintered metal.

By the way, the solid metal material formed by cutting is extremely expensive and expensive, and it is proposed by Japanese Patent Publication No. Sho 49-12225 to obtain a multi-stage helical gear as described above by using a sintered metal. That is, when pressing and forming, the upper and lower punches are engaged with the inclined female thread formed on the outer mold for powder compacting, and either the outer mold or the upper and lower punches are used with a rack and pinion. However, it has been proposed that the same thing be done by using a groove cam or the like.

On the other hand, in spite of these proposals, since there is no integrally molded sintered metal composite gear, as shown in FIG. 6, a large-diameter gear portion body 21 and a small-diameter gear portion body 22 are separately molded. Are fitted together, and the joining pin 23 is fitted to the fitting boundary.
It is performed to drive a plurality of pieces and assemble them in one piece.

[0005]

SUMMARY OF THE INVENTION Conventionally, as a manufacturing facility for a sintered metal multi-stage helical gear, which is indispensable under the condition that strength and heat resistance are required, the one which has been conventionally announced is mechanically forced to punch or external force. Although it is intended to be powder compacted by giving it to the above, it is difficult to obtain sufficient powder compaction in actual operation, even if it can be understood from the illustration or theoretically, it is difficult to obtain sufficient powder compaction, and the wear of the mechanism etc. Is also remarkable.

Further, it is necessary to prepare an angle adjusting jig such as a cam for each size and shape of the product to be molded, and if there is a difference in the twist angle or the like between the jig and the mold, the rotation resistance will be increased. Therefore, a lot of jigs are required, the storage and management of the jigs are complicated, and many kinds of products cannot be produced at low cost. There is a disadvantage.

For this reason, the products shown in FIG. 6 which are actually commercialized must be a multi-step process in which they are individually powder compacted, sintered, fitted and then the joining pins are driven. In addition, the advantages of mass production and low cost of the sintered gold manufacturing technology are greatly reduced.

[0008]

SUMMARY OF THE INVENTION The present invention was devised after repeated studies in view of the above-mentioned circumstances, and is integrally formed while obtaining sufficient strength and an inclined tooth row angle due to a powder compacting structure. The present invention provides a multi-stage helical gear that is fully equipped with the merits of the mass production method, and is as follows.

(1) A powder metal to be compacted is inserted between an outer die having an inclined tooth row on its inner surface and an upper and lower punch, and either the upper or lower punch or the punches engaged with the inclined tooth row. When the inner punch provided coaxially with the heel is pressed to perform powder compacting, the fluid pressure operation mechanism assists the turning action of the punch or the outer die which engages with the inclined tooth row and is turned during the pressing. A method for manufacturing a multi-stage helical gear made of sintered metal, which is characterized in that

(2) The operation process of the punch which is engaged with the inclined tooth row of the outer die and is rotated during the pressing or the fluid pressure operation mechanism which assists the turning action of the outer die, is an auxiliary process for the rolling reduction and a predetermined density. The binding operation according to item (1) above, wherein the operation force of the fluid pressure operation mechanism in the auxiliary step is less than the operation force in the reduction operation step for obtaining a predetermined density. Manufacturing method of multi-stage helical gear made of metal.

(3) The operation force of the fluid pressure operation mechanism in the auxiliary process can be obtained by the gas pressure, and the operation force in the pressure reduction operation process for obtaining the predetermined density can be obtained by the liquid pressure. A method of manufacturing a multi-stage helical gear using the sintered metal according to the item.

[0012]

The powder metal to be compacted is inserted between the outer die having the inclined tooth row on its inner surface and the upper and lower punches, and is coaxial with either the upper or lower punch engaged with the inclined tooth row or the punches. When the inner punch provided is pressed to perform powder compaction, the fluid pressure operation mechanism assists the turning action of the punch or the outer die that engages with the inclined tooth row and is turned during the pressing. The frictional resistance generated at the engaging part during powder molding is greatly reduced, and mechanical stress is almost eliminated, which realizes smooth molding operation and ensures mass productivity.

As described above, the powder pressure molding is accurately performed by assisting with the fluid pressure operation mechanism. Therefore, the inclined tooth row is formed in multiple stages on the peripheral surface, and at least a part of the axis line of the inclined tooth row is formed. A powder compact having an inclination angle of 15 ° or more and a porosity of 18% or less is easily molded to effectively maintain the operation transmission characteristics as a helical gear and to secure the strength. . The porosity is preferably 15% or less, and the lower limit thereof may be about 5%.

By integrally molding the above-mentioned parts, duplicate powder compacting, sintering and subsequent joining steps are not required, and productivity is improved and sufficient cost reduction can be obtained. The upper limit of the inclination angle is about 45 °.

The assisting action of the punch or the outer die by the fluid operation mechanism as described above includes an assisting process for rolling down and a rolling down process for obtaining a predetermined density.
By reducing the operating force in the assisting process to be less than the operating force in the rolling operation process, it is possible to prevent the fluid operation mechanism from receiving an excessive acting force in the assisting process, reduce energy loss and prevent mechanical wear.

The operating force in the assisting process is generally about 1/2 to 1/10 of the operating force in the rolling operation process, and the fluid operating mechanism equipment for carrying out the method of the present invention is a cam mechanism or the like. Since it is simpler and compacter than the one that employs the mechanical structure of connecting and joining, the operating force for operating the equipment itself is relatively small, and it is 1/5 of the operating force for finishing the powder compacting. Hereinafter, it may be particularly 1/10. As the fluid operation mechanism, it is generally preferable to adopt an operation mechanism using air pressure, but particularly when molding a large helical gear, a hydraulic pressure or other hydraulic operation mechanism can be adopted in the rolling operation process.

By obtaining the operating force of the fluid pressure operating mechanism by the gas pressure in the auxiliary process, the pressure fluctuation is absorbed by the fluctuation of the gas volume to obtain a smooth operation, while the rolling operation process for obtaining the predetermined density is performed. By obtaining it by liquid pressure, it can be obtained as a powder compacting action by strong reduction without volume change, and the desired density can be appropriately formed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention as described above will be described with reference to the accompanying drawings. One example of the compound helical gear obtained by the present invention is as shown in FIG. Is inclined to the axis by 20 °
A large-diameter portion 1a formed so as to have a certain angle and a small-diameter portion 1b in which the tooth row 14 is inclined in the opposite direction are integrally formed by an iron-based sintered metal. The sintered metal had a porosity of 6.1% and had a strength comparable to that of a gear obtained by shaving a solid metal body.

The above-mentioned FIG. 1 shows the case where the large diameter portion 1a and the small diameter portion 1b symmetrically adopt the tooth rows 14 and 15 having the same inclination angle, but the one according to the present invention also has a degree of inclination angle. Different from each other to form a helical compound gear as shown in FIG.
Alternatively, as shown in FIG. 3, it can be implemented as a helical gear in which the thickness (gear width) of each step is considerably different. Depending on the case, either the large diameter portion 1a or the small diameter portion 1b may not have an inclination angle with respect to the axis.

The porosity is 9% or less, and the helical gear having an inclination angle of 15 ° or more with respect to the axis of any one of the tooth rows is integrally formed, so that the efficiency of the helical gear is increased and the strength is improved. You can easily obtain excellent products at low cost.

In the present invention, in manufacturing the above-mentioned helical gear, either the upper or lower punch or the upper and lower punches is used for the outer die having the female tooth row mold surface to form the desired tooth row. Using inner punches or cores inserted in one or both of them, the tooth rows formed on the outer peripheral surfaces of these punches are engaged with the female tooth row die surface formed on the inner side of the above outer die to lower the rotation. Alternatively, rotating and raising to perform powder compacting is the same as the conventional one.

In powder compacting as described above, however, either the upper or lower punch or the outer die is engaged with the female tooth row mold surface and the male tooth row corresponding thereto for compacting. Either one or both of the denture row units are rotated, and this rotation power is automatically obtained by pressing or raising the punch or the outer die. An operating cylinder force using fluid pressure is applied to assist the rotational force.

That is, the rotational action force automatically generated by the powder compact (down or rising) under the engagement condition of the female dentition and the male dentition is preferentially or naturally generated, and the rotation is performed by the fluid operation cylinder. It is only intended to reduce the friction that acts between the engaging parts (punch and outer die, etc.) during operation. In this way, the friction between the engaging parts during powder compaction is reduced. The powder action force can be efficiently obtained, and the friction is reduced to reduce the pressure. Therefore, the mechanical unreasonableness caused by forcibly rotating and reducing the pressure is eliminated, and smooth powder compacting can be performed.

A concrete mode is as shown in FIG. 4, in which the outer die 11 is charged with metal powder to be compacted (a solid lubricant or the like is appropriately mixed), and the upper and lower punches 12 and 13 are formed. The rack 16 engaged with the tooth row 19 formed on the outer side of the outer die 11 is fluid cylinder when pressed or raised to perform powder compaction under the above-described engagement condition of the female tooth row and the male tooth row. 1
The moving operation is carried out by 7, 18 to assist the rotation of the outer mold 11. Depending on the case, as shown in FIG. 5, the piston of the operation cylinder 17 or 18 is connected to the outer mold 11, and the axial direction of the operation cylinder 17 pivotally supported at the base end or the middle by the fixed portion is continuously extended according to the expansion and contraction of the piston. Change the outer mold 1
Assist rotation of 1. In any case, the rotation angle is 3 in the angular range on the circumference due to the inclination angle of the engaged male and female teeth rows.
It is easily obtained because it is about double.

In the illustrated example, the operation of the fluid operation cylinder 17 or 18 is applied to the outer die 11, but it may be added to the punch 12 or 13 in some cases, and the outer die 11 and each punch can be used. It is possible to act on both 12 and 13, and when acting on both in this way, the rotational direction with respect to the outer die 11 and the rotational direction with respect to each punch are opposite.

The operation cylinder 17, as described above,
A fluid action force control means such as a valve is provided in a fluid supply or discharge system for the fluid 18, and one or both of the fluid pressure and the amount of fluid supplied to the operation cylinders 17 and 18 are adjusted to adjust the action force. . That is, by such adjustment, the operating condition corresponding to the size, shape or density of the product to be molded can be easily formed without using special cams or other jigs.

In any case, the turning force by the fluid operation cylinder is auxiliary, and the operation of the powder compacting machine or the vertical position of the outer die or the punch is detected to operate in an interlocking manner.
The operation cylinder 17 or 18 is controlled so as not to be actively rotated by the operation cylinder 17 or 18, and the frictional resistance between the outer die and the punch obtained during the powder compacting is obtained. Cancellation of
The action force is in the range of reduction.

Specifically, the compound helical gear shown in FIG. 1 has a large diameter portion (1a) having a diameter of 37 mm and a small diameter portion (1b).
The diameter of each is 23 mm, the thickness (height) of each is 6.5 mm, and the inclination angle to the axis of the tooth row is 24 °. When the powder is charged into the outer mold and pressed by the upper punch, and then pressed by the lower punch with a pressing force of 4 to 7 t / cm ² , each of the outer cylinder is lightly pressed by the operation cylinder. It was rotated by applying acting force.

Regarding the acting force by the operating cylinder, it is preferable to apply the acting force in an assisting or assisting manner even in the process of moving the punch or the die which is performed prior to the compacting. The acting force in the moving process and the acting force at the time of powder compacting are appropriately selected in the range of about 1:10. In the case of the above-mentioned manufacturing example, 2.0 kg / cm ^{2 at} the reinforcing process, 5.0 kg / cm
It was possible to operate smoothly by switching to ² and molding. Further, this acting force was examined by proportionally changing it in the range of 1 to 5 kg / cm ^{2 in} the assisting process and ^{2 to} 10 kg / cm ^{2 in} the powder compacting by the acting force adjusting means as described above. In any case, a suitable product could be obtained.

The porosity of the obtained product is around 12% (10 to 13%), and uniform powder compacts can be mass-produced at about 8 to 10 pieces per minute. It is used as a product and has a tensile strength of 40 kgf / mm.
It was confirmed that the product was ² , which was excellent in strength.

The inventors of the present invention also carried out the production of the compound helical gear as described above from brass-based and bronze-based powder metal, but a porosity of about 15 to 18 vol.% Was obtained by the same method as described above. It was confirmed that the same can be mass-produced.

[0032]

As described above, according to the present invention, it is possible to provide a compacted powder-integrated composite helical gear having a low porosity and an excellent strength, and to obtain a preferable manufacturing method thereof for mass production and low cost. It is an invention that is industrially effective because it can provide excellent products.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an example of a multi-stage helical gear according to the present invention.

FIG. 2 is a partially cutaway perspective view of another example thereof.

FIG. 3 is a partially cutaway perspective view according to still another example.

FIG. 4 is a perspective view showing an outer die rotation assisting method according to the present invention.

5 is a perspective view similar to FIG. 4 showing another example thereof.

FIG. 6 is a partially cutaway perspective view similar to FIG. 1 of a multi-stage helical gear according to the prior art.

[Explanation of symbols]

 1 Multi-stage helical gear 1a Large diameter part 1b Small diameter part 11 Outer mold 12 Upper punch 13 Lower punch 14 Tooth row 15 Tooth row 16 Rack 17 Fluid cylinder 18 Fluid cylinder 21 Large diameter gear body 22 Small diameter gear body 23 Joining pin

Claims (3)

(57) [Claims] 1. A powder metal to be compacted is inserted between an outer die having an inclined tooth row on its inner surface and an upper and lower punch, and either the upper or lower punch engaged with the inclined tooth row or one of those punches. When the inner punch provided coaxially is pressed to perform powder compaction, the fluid pressure operation mechanism assists the turning action of the punch or the outer die which is engaged with the inclined tooth row and is turned during the pressing. A method of manufacturing a multi-stage helical gear made of sintered metal. 2. An operation process of a punch which is engaged with a tilted tooth row of an outer die and is rotated when being pressed, or a fluid pressure operation mechanism which assists a turning action of the outer die, an assisting process for the reduction and a predetermined density. The multistage step by sintered metal according to claim 1, characterized in that the operation force of the fluid pressure operation mechanism in the auxiliary process is less than the operation force in the reduction operation process for obtaining a predetermined density. Manufacturing method of helical gear. 3. The operation force of the fluid pressure operation mechanism in the auxiliary process can be obtained by gas pressure, and the operation force in the pressure reduction operation process for obtaining a predetermined density can be obtained by liquid pressure. For manufacturing multi-stage helical gears using sintered metal.