JP7149150B2 - Rack bar manufacturing equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a manufacturing apparatus for rack bars used in automobile steering devices and the like.

A rack bar has a rack formed on a shaft member, and a rack bar made of a hollow shaft member is also known for weight reduction. A rack bar made of a hollow shaft member is manufactured by press-fitting a core bar into a hollow shaft member whose outer periphery is held by a mold, for example. By press-fitting the cored bar, the shape of the mold is transferred to the outer periphery of the shaft member, and a rack is formed on the outer periphery of the shaft member (see Patent Document 1, for example).

The rack bar manufacturing apparatus described in Patent Document 1 includes an upper die having a rack tooth profile, a lower die, a movable upper die holder that holds the upper die, and a fixed lower die holder that holds the lower die. Prepare. The lower mold holder has a groove, and the lower mold is fixed to the bottom of the groove. The upper die is moved integrally with the upper die holder and vertically moved within the groove of the lower die holder. The shaft is sandwiched and held between the upper and lower dies, and the cored bar is press-fitted into the shaft held by the upper and lower dies.

Also, rack bars made of hollow shafts are typically quenched to increase the hardness of the rack. However, since the cross-sectional shape of the rack forming section of the shaft member is asymmetrical and the residual stress during rack processing is high, bending is likely to occur due to quenching. Therefore, as a method of quenching a rack bar made of a hollow shaft member, there is known a method of quenching while restraining the rack forming section from the vertical direction and the lateral direction (see, for example, Patent Document 2).

JP 2008-229675 A JP-A-2000-119739

In the rack bar manufacturing apparatus described in Patent Document 1, the upper die slides on the side surface of the groove of the lower die holder in response to vertical movement. Therefore, an appropriate clearance is provided between the upper mold and the side surface of the groove of the lower mold holder. Here, the shaft into which the cored bar is press-fitted is pressed radially outward by the cored bar, and the upper and lower dies holding the shaft are also pressed radially via the shaft. The load acting on the upper die and the lower die is supported by the upper die holder and the lower die holder. is provided. Therefore, the upper die radially pressed by the shaft member is spread laterally by the clearance between the upper die and the side surface of the groove of the lower die holder.

When the upper die is pushed out in the horizontal direction, the shaft material also bulges in the horizontal direction, and there is a risk that the straightness and circularity of the rack-forming section of the shaft material will be reduced. If the straightness and circularity of the rack forming section are lowered, the constraint of the rack forming section will not be constant in the length direction when the rack bar is quenched, and there is a risk that the accuracy of the rack will be reduced. . On the other hand, when the clearance between the upper die and the side surface of the groove of the lower die holder is narrowed, the deformation of the upper die is suppressed, but the smooth movement of the upper die is hindered, and the rack bar manufacturing apparatus is damaged. Operation may be hindered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rack bar manufacturing apparatus capable of ensuring operability and improving rack accuracy.

The apparatus for manufacturing a rack bar according to one aspect of the present invention transfers the shape of the mold to the outer circumference of the shaft member by press-fitting the core bar into the hollow shaft member whose outer circumference is surrounded by the mold. A rack bar manufacturing apparatus for forming a rack on the outer circumference of the shaft member, comprising: the mold; an upper mold having a molding groove that forms a molding space between the lower mold and the upper mold, wherein the holder includes a movable upper mold holder that holds the upper mold and a holding groove that holds the lower mold and a lower mold holder in which the upper mold that is moved integrally with the upper mold holder moves up and down within the holding groove; The clearance between the lower part of the upper mold and the side surfaces of the holding groove on both sides in the width direction from the lower surface to the depth of the forming groove or more is less than the clearance between

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing apparatus of the rack bar which can ensure operability and can raise the precision of a rack can be provided.

1 is a perspective view of an example rack bar for describing an embodiment of the present invention; FIG. 1. It is a schematic diagram which shows the outline of the manufacturing process of the rack bar of FIG. 1. It is a schematic diagram which shows the outline of the manufacturing process and manufacturing apparatus of the rack bar of FIG. FIG. 2 is a cross-sectional view of the rack bar manufacturing apparatus of FIG. 1; 5 is a cross-sectional view of a main part of the manufacturing apparatus of FIG. 4; FIG. FIG. 5 is a plan view of a rack bar manufactured by the manufacturing apparatus of FIG. 4; FIG. 5 is a cross-sectional view of a modification of the manufacturing apparatus of FIG. 4; FIG. 5 is a cross-sectional view of another modification of the manufacturing apparatus of FIG. 4; FIG. 5 is a plan view of a preferred configuration example of a cored bar provided in the manufacturing apparatus of FIG. 4; FIG. 10 is a side view of the core bar of FIG. 9; FIG. 5 is a plan view of a preferred configuration example of a first cored bar push rod provided in the manufacturing apparatus of FIG. 4 ; FIG. 12 is a schematic diagram showing an example of a preferable manufacturing process of a rack bar using a manufacturing apparatus having the cored bar of FIGS. 9 and 10 and the first cored bar push rod of FIG. 11 ; FIG. 12 is a schematic diagram showing an example of a preferable manufacturing process of a rack bar using a manufacturing apparatus having the cored bar of FIGS. 9 and 10 and the first cored bar push rod of FIG. 11 ; FIG. 12 is a schematic diagram showing an example of a preferable manufacturing process of a rack bar using a manufacturing apparatus having the cored bar of FIGS. 9 and 10 and the first cored bar push rod of FIG. 11 ; FIG. 5 is a schematic diagram of a preferred configuration example of the manufacturing apparatus of FIG. 4; FIG. 16 is a schematic diagram showing the operation of the manufacturing apparatus of FIG. 15; 5 is a schematic diagram of another preferred configuration example of the manufacturing apparatus of FIG. 4. FIG. FIG. 18 is a schematic diagram showing a preferable manufacturing process example of a rack bar using the manufacturing apparatus of FIG. 17; FIG. 18 is a schematic diagram showing a preferable manufacturing process example of a rack bar using the manufacturing apparatus of FIG. 17; FIG. 18 is a schematic diagram showing a preferable manufacturing process example of a rack bar using the manufacturing apparatus of FIG. 17;

FIG. 1 shows an example of a rack bar for describing embodiments of the present invention.

The rack bar 1 is a rack bar made of a hollow shaft member 2 having a circular cross section, and both ends of the shaft member 2 in the axial direction are open. A rack 3 is formed in a partial section of the length of the shaft member 2 . A section in which the rack 3 is formed (hereinafter referred to as a rack forming section) has a non-circular cross-sectional shape, and a section outside the rack forming section has a circular cross-sectional shape. The rack bar 1 is manufactured, for example, as follows.

2 and 3 show an outline of a manufacturing apparatus and a manufacturing process of the rack bar 1. FIG.

The shaft member 2 is a hollow shaft member made of steel such as JIS-S45C. The shaft member 2 is typically subjected to a bonderizing treatment that enhances moldability and corrosion resistance.

As shown in FIG. 2 , a flattened portion 4 extending in the axial direction of the shaft member 2 is formed in a portion of the length of the shaft member 2 . A rack 3 is formed on the flat outer surface of the flattened portion 4 by a hollow rack bar manufacturing apparatus 10 described below. The flattened portion 4 is formed, for example, by flattening a portion of the length of the shaft member 2 to near the tooth bottom height of the rack 3 by press working.

As shown in FIG. 3, a hollow rack bar manufacturing apparatus 10 includes a metal mold 11, a plurality of metal cores 12, a metal core holder 13 for holding the multiple metal cores 12, and a first metal core push rod 14. , and a second mandrel push rod 15 .

A portion of the length of the shaft member 2 including the flattened portion 4 is held by the mold 11 . The mold 11 has an upper mold 16 and a lower mold 17 . The upper mold 16 and the lower mold 17 are opened and closed by a mold clamping mechanism (not shown) to vertically sandwich the shaft 2 and hold the outer periphery of the shaft 2 . A rack tooth mold 18 is detachably attached to the upper mold 16 , and the rack tooth mold 18 is fixed in contact with the substantially flat outer surface of the flattened portion 4 . A plurality of tooth grooves for forming the rack 3 are provided on the molding surface 18 a of the rack tooth mold 18 that is in contact with the outer surface of the flattened portion 4 .

One of the plurality of cored bars 12 held by the cored bar holder 13 is inserted into the shaft member 2 from the first opening 5 on one axial end side of the shaft member 2 to form the first cored bar. It is press-fitted inside the flattened portion 4 by a push rod 14 . Then, the press-fitted core bar 12 is pushed back by a second core bar push rod 15 inserted into the shaft member 2 from the second opening 6 on the other axial end side of the shaft member 2 and discharged from the shaft member 2 . be. While the core metal 12 is reciprocated over the entire length of the flattened portion 4 , the material of the flattened portion 4 is squeezed by the core metal 12 and plastically flows toward the rack teeth 18 . As the core metal 12 is gradually replaced with a larger one and the core metal 12 is repeatedly press-fitted, the material of the flattened portion 4 gradually bites into the tooth spaces of the molding surface 18a of the rack tooth mold 18, and the shape of the molding surface 18a is changed. It is transferred to the flattened portion 4 and the rack 3 is formed on the flattened portion 4 .

The shaft member 2 with the racks 3 formed thereon is subjected, if necessary, to correction of the curvature associated with forming the teeth, grinding of the outer peripheral surface, and quenching to increase the hardness of the racks 3 . Heating for quenching can be performed, for example, by high-frequency induction heating, but is not limited to high-frequency induction heating. Moreover, the heating range during quenching is not particularly limited as long as it includes the rack forming section, and may be the rack forming section alone or the entire length of the shaft member 2 . Moreover, during quenching, preferably, the rack forming section is restrained from the vertical direction and the lateral direction, as in the quenching method described in Patent Document 2, so that bending of the shaft member 2 due to quenching is prevented. Suppressed.

4 and 5 show the configuration of the mold 11 and the holder that holds the mold 11. FIG.

The mold 11 has an upper mold 16 and a lower mold 17, and the holder 20 that holds the mold 11 has an upper mold holder 21 that holds the upper mold and a lower mold holder 22 that holds the lower mold 17. . The upper mold holder 21 is vertically moved by the mold clamping mechanism (not shown). Lower die holder 22 is supported by holder support frame 23 , and holder support frame 23 is fixed to base 24 of manufacturing apparatus 10 .

The lower mold holder 22 has a holding groove 25 which is open to the upper surface of the lower mold holder 22 and formed across the lower mold holder 22 in the longitudinal direction of the holding groove 25 . The lower die 17 is fitted into the holding groove 25 and fixed to the bottom of the holding groove 25 . The upper die 16, which is vertically moved integrally with the upper die holder 21, is vertically moved within the holding groove 25, and slides along the lateral sides 25a and 25b of the holding groove 25 along the vertical movement. The mold 11 is opened and closed according to the vertical movement of the upper mold 16 .

With the mold 11 closed, the lower surface 16a of the upper mold 16 and the upper surface 17a of the lower mold 17 are butted against each other. Forming grooves 26 crossing the lower surface 16a in the length direction of the holding grooves 25 are formed in the lower surface 16a of the upper mold 16, and the upper surface 17a of the lower mold 17 also extends in the length direction of the holding grooves 25. A transverse shaped groove 27 is formed. By combining the molding groove 26 of the upper mold 16 and the molding groove 27 of the lower mold 17, the molding space surrounding the outer periphery of the partial section of the length of the shaft material 2 including the flattened portion 4 is formed between the upper mold 16 and the lower mold. It is formed between the mold 17 and the mold 17 . The rack tooth mold 18 is attached to the upper mold 16 with the molding surface 18a of the rack tooth mold 18 protruding into the molding space.

A main cooling path 28 is provided inside the lower die holder 22 and the holder support frame 23 , and a sub cooling path 29 is provided inside the upper die 16 . The main cooling path 28 is formed inside the lower mold holder 22 so as to surround the lower mold 17 . The sub cooling path 29 communicates with the main cooling path 28 when the mold 11 is closed, and is disconnected from the main cooling path 28 when the mold 11 is open. The communicating portion of the sub-cooling path 29 that communicates with the main cooling path 28 is closed by the side surface of the upper mold 16 when the mold 11 is open.

A coolant circulation device (not shown) having a liquid cooler is connected to the inlet 30 and outlet 31 of the main cooling passage 28 . For example, during operation of the manufacturing apparatus 10 , the cooling liquid circulation device is continuously operated, and the cooling liquid is circulated through the main cooling path 28 and the sub cooling path 29 . By circulating the cooling liquid through the main cooling path 28 and the sub-cooling path 29, the temperature rise of the upper die 16, the lower die 17, and the rack tooth die 18 is suppressed, and the thermal expansion due to the temperature rise is suppressed. This increases the accuracy of the rack 3 .

An oil supply passage 32 is provided inside the lower die holder 22 and the holder support frame 23 . Further, injection nozzles 33 are provided on both side surfaces 25 a and 25 b of the holding groove 25 in the width direction, and the oil supply passage 32 is connected to the pair of injection nozzles 33 . The injection nozzle 33 extends in the lengthwise direction of the holding groove 25, and the injection nozzle 33 is provided with a plurality of injection holes spaced apart in the lengthwise direction.

An oil supply device (not shown) is connected to the inlet 34 of the oil supply passage 32 . For example, each time the mold 11 is opened, the lubricating device pumps a predetermined amount of machining oil, and the machining oil is injected from each injection hole of the pair of injection nozzles 33 toward the molding surface 18a of the rack tooth mold 18. The machining oil is sprayed onto the molding surface 18a of the rack tooth mold 18 to clean the molding surface 18a. As the rack 3 is molded, a part of the film formed on the outer surface of the shaft member 2 by the bonderizing process may adhere to the molding surface 18a. Foreign matter such as dust is removed from the molding surface 18a. As a result, defective molding of the rack 3 caused by foreign matter adhering to the molding surface 18a is avoided.

As shown in FIG. 5, the portion extending from the lower surface 16a of the upper mold 16 to the depth of the molding groove 26 or more is defined as the lower portion 35 of the upper mold 16, and side surfaces 35a and 35b on both sides in the width direction of the lower portion 35 of the upper mold 16 are formed. are protruded from side surfaces 36a and 36b on both sides in the width direction of the upper portion 36 of the upper mold 16. As shown in FIG. Since both side surfaces 35a and 35b of the lower portion 35 of the upper mold 16 are relatively protruded, the lower portion 35 of the upper mold 16 and the holding groove 25 on both sides in the width direction can A clearance C1 between the side surfaces 25a and 25b is smaller than a clearance C2 between the upper portion 36 of the upper die 16 and the side surfaces 25a and 25b on both sides of the holding groove 25 in the width direction.

Here, the shaft member 2 into which the core metal 12 is press-fitted is pressed radially outward by the core metal 12 , and the upper die 16 and the lower die 17 that hold the shaft member 2 also move radially through the shaft member 2 . pressed to. In particular, the lower portion 35 of the upper mold 16 provided with the molding groove 26 is subjected to a stronger pressing force in the width direction than the upper portion 36 . However, the clearance C1 between the lower portion 35 of the upper mold 16 and the side surfaces 25a and 25b of the holding groove 25 is relatively small, and the widthwise expansion of the lower portion 35 caused by the pressing force is suppressed.

By suppressing the expansion of the lower portion 35 of the upper die 16 in the width direction, the lateral expansion of the rack-forming section of the shaft member 2 as indicated by the two-dot chain line in FIG. 6 is also suppressed. Thereby, the straightness and roundness of the rack forming section of the shaft member 2 are maintained. As described above, the shaft member 2 on which the racks 3 are formed is quenched in a state in which the rack-forming section is restrained from the vertical and horizontal directions, but the straightness and roundness of the rack-forming section are maintained. As a result, the restraint of the rack formation section becomes constant in the length direction, and the accuracy of the rack 3 is improved.

On the other hand, the clearance C2 between the upper portion 36 of the upper die 16 and the side surfaces 25a and 25b of the holding groove 25 is relatively large, and smooth movement of the upper die 16 is ensured. Thereby, the operation of the manufacturing apparatus 10 is stabilized.

As shown in FIG. 7, when the mold 11 is closed, of the side surfaces 25a and 25b on both sides in the width direction of the holding groove 25, the regions facing the upper portion 36 of the upper mold 16 are upper regions 25a1 and 25b. 25b1, and regions facing the lower portion 35 of the upper mold 16 are defined as lower regions 25a2 and 25b2. The clearance C1 between the grooves 25 may be smaller than the clearance C2 between the upper part 36 of the upper die 16 and the holding grooves 25 .

When both side surfaces 35a and 35b of the lower portion 35 of the upper die 16 are relatively convex (see FIG. 5), and when the upper regions 25a1 and 25b1 of both side surfaces 25a and 25b of the holding groove 25 are relatively concave. In either case (see FIG. 7), preferably one on both sides 35a, 35b of the lower part 35 of the upper mold 16 and/or the lower regions 25a2, 25b2 on both sides 25a, 25b of the holding groove 25 The concave portion 37 described above is provided, and the lubricant is held in the concave portion 37 . As a result, the upper die 16 can be moved more smoothly, and the operation of the manufacturing apparatus 10 can be further stabilized.

Further, as shown in FIG. 8, a pair of pressing members 38 and a drive section 39 for moving the pair of pressing members 38 may be provided. The drive unit 39 has a pair of pressure chambers 40, and the pair of pressure chambers 40 are provided in the holder support frame 23 across the holding groove 25 in the width direction. Each pressure chamber 40 is provided with an insertion hole 41 extending from each pressure chamber 40 to the holding groove 25 in the width direction of the holding groove 25 . The pressing member 38 has a partition wall 42 and a pressing rod 43 extending from the partition wall 42 . The partition wall 42 is housed in the pressure chamber 40 , and the pressing rod 43 is housed in the insertion hole 41 . The partition 42 bisects the pressure chamber 40 in the width direction of the holding groove 25 and is movable back and forth in the pressure chamber 40 in the width direction of the holding groove 25 . As the partition wall 42 moves back and forth, the tip of the pressing rod 43 protrudes into the holding groove 25 or is housed in the insertion hole 41 .

The drive unit 39 further has a supply/discharge device 44 for supplying/discharging a pressure medium such as oil, and supply/discharge paths 45a and 45b for circulating the pressure medium. The pressure chamber 40 is divided into a first pressure chamber 40a and a second pressure chamber 40b by a partition wall 42. A supply/discharge passage 45a communicates with the first pressure chamber 40a. It communicates with the second pressure chamber 40b. By supplying the pressure medium to the first pressure chamber 40a and discharging the pressure medium from the second pressure chamber 40b, the tip of the pressing rod 43 protrudes into the holding groove 25, and conversely, the first pressure chamber By discharging the pressure medium from 40a and supplying the pressure medium to the second pressure chamber 40b, the tip portion of the pressing rod 43 is housed in the insertion hole 41. As shown in FIG.

The supply/discharge device 44 supplies the pressure medium to the first pressure chambers 40a of the pair of pressure chambers 40 when the mold 11 is closed. By supplying the pressure medium to the first pressure chamber 40a, the tip portions of the pair of pressing rods 43 protrude from both side surfaces 25a and 25b of the holding groove 25, and the lower portion 35 of the upper die 16 is pushed by the pair of pressing rods 43. It is sandwiched in the width direction. That is, the clearance C1 between the lower portion 35 (see FIGS. 5 and 7) of the upper mold 16 and the side surfaces 25a and 25b of the holding groove 25 becomes zero. As a result, the expansion of the lower portion 35 of the upper mold 16 in the width direction is further suppressed against the pressing force acting on the upper mold 16 due to the press-fitting of the cored bar 12 .

On the other hand, the supply/discharge device 44 supplies the pressure medium to the second pressure chamber 40b of each of the pair of pressure chambers 40 when the mold 11 is opened and closed. By supplying the pressure medium to the second pressure chamber 40 b , the tip portions of the pair of pressing rods 43 are accommodated in the insertion holes 41 . That is, the clearance C1 between the lower portion 35 (see FIGS. 5 and 7) of the upper die 16 and the side surfaces 25a and 25b of the holding groove 25 is the upper portion 36 (see FIGS. 5 and 7) of the upper die 16 and the holding groove 25. It is enlarged to the same extent as the clearance C2 between both side surfaces 25a and 25b of the groove 25. As shown in FIG. This allows the upper die 16 to move more smoothly.

A preferred configuration example of the manufacturing apparatus 10 described above will be described below.

9 and 10 show a preferred configuration example of the cored bar 12, and FIG. 11 shows a preferred configuration example of the first cored bar push rod 14. FIG.

As shown in FIGS. 9 and 10, the core metal 12 has a cylindrical bottom surface 12a along the inner peripheral surface of the shaft member 2 and a pair of side surfaces 12b and 12c extending substantially parallel upward from both ends of the bottom surface 12a. , and an upper surface 12d connecting the upper ends of the pair of side surfaces 12b and 12c. A plurality of protrusions 50 are provided on the upper surface 12 d of the core metal 12 , and the plurality of protrusions 50 are arranged at intervals in the length direction of the core metal 12 . The heights of the projections 50 of the plurality of core metals 12 to be press-fitted into the shaft member 2 are different from each other, and the core metals 12 having relatively low projections 50 are press-fitted into the shaft member 2 in order. Then, the cored bar 12 is press-fitted into the shaft member 2 so that the convex portion 50 slides on the flattened portion 4 (see FIG. 3) of the shaft member 2 .

A detent portion 51 is provided at one end portion of the core bar 12 in the length direction. In the example shown in FIG. 9 , the anti-rotation portion 51 is formed by a cylindrical concave curved surface 51 a , and the center axis of the concave curved surface 51 a is substantially parallel to the vertical direction of the cored bar 12 . The anti-rotation portion 51 is not limited to being formed by a cylindrical concave curved surface. For example, the anti-rotation portion 51 may be formed by a cylindrical convex curved surface. may be formed by recesses or protrusions that are arranged off the .

As shown in FIG. 11, the first cored bar push rod 14 for press-fitting the cored bar 12 into the shaft member 2 has an insertion portion 52 that is inserted into the shaft member 2 together with the cored bar 12. The length of the inserted portion 52 is The cross-sectional shape perpendicular to the direction is substantially the same as the cross-sectional shape perpendicular to the length direction of the cored bar 12 . A distal end portion 53 of the insertion portion 52 can be engaged with the anti-rotation portion 51 of the cored bar 12 . In the example shown in FIG. 11, the distal end portion 53 of the insertion portion 52 is formed by a cylindrical convex curved surface 53a corresponding to the anti-rotation portion 51 formed by the cylindrical concave curved surface 51a.

When the anti-rotation portion 51 of the cored bar 12 is formed with a cylindrical convex curved surface, the distal end portion 53 of the insertion portion 52 is formed with a cylindrical concave curved surface. Further, when the anti-rotation portion 51 is formed by a recess that is arranged away from the central axis of the cylindrical bottom surface 12 a of the core metal 12 , the distal end portion 53 of the insertion portion 52 is positioned in the recess of the anti-rotation portion 51 . When the anti-rotation portion 51 is formed by a concave portion arranged off the center axis of the bottom surface 12a, the distal end portion 53 of the insertion portion 52 is formed by a convex portion to be fitted to the anti-rotation portion 51. formed by a recess that fits into the

12 to 14 show an example of a preferable manufacturing process of the rack bar 1 when the cored bar 12 and the first cored bar push rod 14 have the above-described configurations.

As shown in FIG. 12 , one of the plurality of cored bars 12 held by the cored bar holder 13 is arranged by the cored bar holder 13 so as to face the first opening 5 of the shaft member 2 . be done. Then, the first mandrel push rod 14 is moved, and the anti-rotation portion 51 of the mandrel 12 arranged to face the first opening 5 of the shaft member 2 and the insertion portion 52 of the first mandrel push rod 14 are opened. is engaged with the tip portion 53 of the . The second mandrel push rod 15 is located at the standby position P1, and the tip of the insertion portion 54 of the second mandrel push rod 15 is arranged to face the second opening 6 of the shaft member 2. .

Next, as shown in FIG. 13, the second mandrel push rod 15 is moved to the set position P2, and the insertion portion 54 of the second mandrel push rod 15 is inserted into the shaft member 2 from the second opening 6 of the shaft member 2. 2 is inserted. The distal end portion of the insertion portion 54 inserted through the shaft member 2 protrudes from the first opening 5 of the shaft member 2 and abuts against the metal core 12 arranged to face the first opening 5 . As a result, the cored bar 12 is sandwiched between the first cored bar push rod 14 and the second cored bar push rod 15 .

Next, as shown in FIG. 14 , the first mandrel push rod 14 and the second mandrel push rod 15 holding the mandrel 12 are moved in synchronism, and the mandrel 12 is moved to the first position of the shaft member 2 . is inserted into the shaft member 2 through the opening 5 of the flattened portion 4 and press-fitted into the flattened portion 4 . Subsequently, the first mandrel push rod 14 and the second mandrel push rod 15 are moved synchronously, and the press-fitted mandrel 12 is pushed back and ejected from the shaft member 2 .

By moving the first and second mandrel push rods 14 and 15 synchronously, the mandrel 12 is sandwiched between the first and second mandrel push rods 14 and 15. maintained. Therefore, the engagement between the anti-rotation portion 51 of the cored bar 12 and the tip portion 53 of the first cored bar push rod 14 is maintained, and the rotation of the cored bar 12 is prevented. As a result, the convex portion 50 of the core metal 12 slides properly on the flattened portion 4 of the shaft member 2, and the precision of the rack 3 formed on the flattened portion 4 is enhanced.

15 and 16 show a preferred configuration example of the manufacturing apparatus 10 when the first mandrel push rod 14 and the second mandrel push rod 15 are moved synchronously.

When the first mandrel push rod 14 and the second mandrel push rod 15 are moved synchronously, a push rod drive unit is provided for each push rod of the first mandrel push rod 14 and the second mandrel push rod 15. However, preferably, the first mandrel push rod 14 and the second mandrel push rod 15 are connected, and the connected first mandrel push rod 14 and the second mandrel push rod 15 are united. Moved by one push rod drive. The manufacturing apparatus 10 shown in FIGS. 15 and 16 includes a first connecting member 60 that moves integrally with the first mandrel push rod 14 and a second connecting member 60 that moves integrally with the second mandrel push rod 15. A member 61 , connecting means 62 for connecting the first connecting member 60 and the second connecting member 61 , and one push rod driving portion 63 are provided.

The first core push rod 14 is held by a first moving table 64 installed on the base 24 , and the first moving table 64 is a first core that is inserted into and removed from the shaft member 2 . It is movable in the moving direction of the gold push bar 14 . The first connecting member 60 is fixed to a first moving table 64 and is moved integrally with the first mandrel push rod 14 and the first moving table 64 under the base 24 .

The second mandrel push rod 15 is held by a second moving table 65 installed on the base 24 , and the second moving table 65 serves as a second core to be inserted into and removed from the shaft member 2 . It is movable in the moving direction of the gold push rod 15 . The second connecting member 61 is fixed to a second moving table 65 and is moved integrally with the second mandrel push rod 15 and the second moving table 65 under the base 24 . Then, when the second connecting member 61 is moved to the position corresponding to the setting position P2 of the second mandrel push rod 15, the first connecting member 60 and the second connecting member 61 are connected by the connecting means 62. concatenated.

The connecting means 62 connects the first connecting member 60 and the second connecting member 61 so as to be cuttable. The connecting means 62 is, for example, a pin that continuously penetrates the first connecting member 60 and the second connecting member 61. Attachment and detachment of the pin to and from the first connecting member 60 and the second connecting member 61 can be performed by the motor. etc., automatically.

The push rod drive unit 63 includes a linear actuator and reciprocates the first moving table 64 holding the first core push rod 14 . In a state in which the first connecting member 60 and the second connecting member 61 are connected by the connecting means 62, the movement of the first moving base 64 also causes the second moving base 65 to move. The second mandrel push rod 15 held on the moving table 65 is moved in the same direction as the first mandrel push rod 14 .

The first mandrel push rod 14 and the second mandrel push rod 15 are connected by a connecting means 62, and the connected first mandrel push rod 14 and the second mandrel push rod 15 form a single push rod drive unit. By being moved by 63, the first mandrel push rod 14 and the second mandrel push rod 15 are easily and reliably synchronously moved. Therefore, the state in which the core 12 is sandwiched between the first core push rod 14 and the second core push rod 15 is also reliably maintained. In addition, the manufacturing apparatus 10 can be made more compact than when a push rod drive unit is provided for each push rod of the first core push rod 14 and the second core push rod 15 .

It should be noted that the second moving table 65 is moved by the driving section 66 in a state where the connection between the first connecting member 60 and the second connecting member 61 is cut. For example, until the second mandrel push rod 15 is moved from the standby position P1 to the set position P2 and the first connecting member 60 and the second connecting member 61 are connected by the connecting means 62, the second moving table 65 is moved. is moved by the drive unit 66 . The driving portion 66 is, for example, an air cylinder or the like, and can be a linear actuator that is smaller than the push-rod driving portion 63 for pressing the cored bar 12 into the shaft member 2 and pushing back the pressed-in cored bar 12 .

FIG. 17 shows another preferred configuration example of the manufacturing apparatus 10. As shown in FIG.

The manufacturing apparatus 10 shown in FIG. 17 includes a mold release mechanism 70 and a set mechanism 80, and is configured so that the shaft material 2 is automatically supplied to and discharged from the mold 11. As shown in FIG. In addition, when a portion of the length of the shaft member 2 including the flattened portion 4 is held by the mold 11, the end of the shaft member 2 on the side of the second opening 6 is held by the mold. It is long enough to protrude from 11 . A portion of the shaft member 2 that protrudes from the mold 11 is hereinafter referred to as a projecting portion 7 .

The mold release mechanism 70 is for separating the shaft 2 with the rack 3 formed thereon from the upper mold 16 and the rack tooth mold 18 , and has a mold release member 71 and lifting means 72 . The release member 71 is provided between the mold 11 and the second core push rod 15 arranged at the standby position P1. The release member 71 has a through portion 73 through which the shaft member 2 can be inserted. The hole shape of the through portion 73 is not limited to a circular shape, and may be a C shape with a cut. The elevating means 72 elevates the release member 71 using a motor or the like. The shaft member 2 on which the rack 3 is formed is separated from the upper mold 16 and the rack tooth mold 18 by lowering the mold release member 71 by the lifting means 72 .

The setting mechanism 80 supplies and discharges the shaft member 2 to and from the mold 11 while the mold 11 is open, and has a setting member 81 and a driving portion 82 . The set member 81 is provided on the side opposite to the mold 11 with the release member 71 as a boundary. The set member 81 has a chuck 83 that detachably holds the shaft member 2 . The drive unit 82 moves the set member 81 using a motor or the like so that the chuck 83 moves in the direction of contacting and separating from the mold 11 and in the vertical direction.

18 to 20 show a preferred manufacturing process example of the rack bar 1 in the case where the manufacturing apparatus 10 includes the releasing mechanism 70 and the setting mechanism 80. FIG.

As shown in FIG. 18, with the mold 11 opened, the release member 71 of the release mechanism 70 is placed at the standby position, and the chuck 83 of the set mechanism 80 is placed at the standby position. . The mold release member 71 is held in the lowest state at the standby position, and the through portion 73 of the mold release member 71 faces one end of the molding groove 27 of the lower mold 17 .

Next, the driving portion 82 of the setting mechanism 80 is operated, the chuck 83 grips the projecting portion 7 of the shaft 2 , and the shaft 2 gripped by the chuck 83 is inserted into the mold 11 . A part of the length of the shaft member 2 including the flattened portion 4 is inserted through the through portion 73 of the release member 71 and set in the molding groove 27 of the lower mold 17 . After this, the mold 11 is closed. The protruding portion 7 of the shaft member 2 gripped by the chuck 83 is arranged to protrude from the mold 11 .

The core 12 is repeatedly press-fitted into the shaft 2 held by the mold 11 by the first core pressing rod 14 and the second core pressing rod 15 , and the rack 3 is formed on the flattened portion 4 of the shaft 2 . is formed. The steps of press-fitting the cored bar 12 and forming the rack 3 are as shown in FIGS.

Next, the shaft member 2 with the rack 3 formed thereon is removed from the mold 11 . As shown in FIG. 19, when the mold 11 is opened, the rack 3 is attached to the rack tooth mold 18, and the shaft member 2 is moved integrally with the ascending upper mold 16 and the rack tooth mold 18. . The driving part 82 of the setting mechanism 80 is operated in synchronization with the upward movement of the upper mold 16 and the rack tooth mold 18, and the chuck 83 gripping the projecting portion 7 of the shaft member 2 is also elevated. At the same time, the elevating means 72 of the mold release mechanism 70 is operated in synchronization with the lifting of the upper mold 16 and the rack tooth mold 18, and the mold release member 71 is also lifted.

As shown in FIG. 20, after the mold opening of the mold 11 is completed, the elevating means 72 of the mold release mechanism 70 and the drive unit 82 of the set mechanism 80 are operated synchronously, and the mold release member 71 and the chuck 83 are moved. descended. The shaft member 2 inserted through the through portion 73 of the mold release member 71 is pressed downward by the mold release member 71 , and the shaft member 2 is separated from the upper mold 16 and the rack tooth mold 18 .

Finally, the chuck 83 gripping the projecting portion 7 of the shaft member 2 is moved away from the mold 11 by the driving portion 82 of the setting mechanism 80 . As a result, the shaft member 2 is pulled out from the mold 11 through the through portion 73 of the release member 71 .

As described above, the rack bar manufacturing apparatus disclosed in the present specification presses a core bar into a hollow shaft member surrounded by a die to change the shape of the die to the shaft member. A rack bar manufacturing apparatus for forming a rack on the outer circumference of the shaft member by transferring to the outer circumference of the shaft member, comprising the mold and a holder for holding the mold, wherein the mold is a lower mold and an upper mold having a molding groove that forms a molding space surrounding the outer periphery of the shaft between the lower mold and the lower mold, the holder comprising: a movable upper mold holder that holds the upper mold; a lower mold holder having a holding groove for holding the lower mold, wherein the upper mold moved integrally with the upper mold holder moves up and down within the holding groove, and the mold is closed. In this state, the clearance between the lower part of the upper mold and the side surfaces of the holding groove in the width direction extending from the lower surface of the upper mold to the depth of the forming groove or more is the clearance between the upper part of the upper mold and the holding groove. It is smaller than the clearance between the side surfaces on both sides in the width direction of the groove.

Further, in the rack bar manufacturing apparatus disclosed in the present specification, both side surfaces in the width direction of the lower portion of the upper mold project toward both side surfaces in the width direction of the upper portion of the upper mold. .

Further, in the rack bar manufacturing apparatus disclosed in this specification, the upper region facing the upper portion of the upper die on both side surfaces in the width direction of the holding groove is a lower region facing the lower portion of the upper die. It is recessed with respect to the area.

Further, in the rack bar manufacturing apparatus disclosed in this specification, the lubricant is held in the lower regions of the side surfaces on both width direction sides of the lower portion of the upper die and/or the side surfaces on both width direction sides of the holding groove. One or more recesses are provided for

Further, the rack bar manufacturing apparatus disclosed in the present specification is provided with the holding groove sandwiched in the width direction of the holding groove, and a pair of pressing members protruding from side surfaces on both sides in the width direction of the holding groove. When the mold is closed, the pair of pressing members protrude from both side surfaces in the width direction of the holding groove and sandwich the lower portion of the upper mold.

Further, the rack bar manufacturing apparatus disclosed in this specification includes a first core push rod inserted into the shaft member through a first opening on one axial end side of the shaft member; a second mandrel push rod inserted into the shaft member through a second opening on the other end side of the direction, wherein the mandrel has a detent portion; a tip portion that engages with a detent portion, the tip portion of the first core metal push rod and the detent portion of the core metal are engaged, and the core metal is connected to the first core metal push rod; and the second mandrel push rod, the mandrel is press-fitted into the shaft member by the first mandrel push rod and pushed back by the second mandrel push rod.

Further, the rack bar manufacturing apparatus disclosed in this specification includes a first connecting member that moves integrally with the first mandrel push rod, and a second connecting member that moves integrally with the second mandrel push rod. 2 connecting members, the first connecting member and the second connecting member are connected, and the state in which the core bar is sandwiched between the first core metal push rod and the second core metal push rod is maintained. and a single push-rod drive unit for moving the first core push rod and the second core push rod while the first connection member and the second connection member are connected to each other. And prepare.

Further, in the rack bar manufacturing apparatus disclosed in the present specification, the mold holds the shaft member in a state in which at least one end of the shaft member protrudes outside the mold; A mold release mechanism is provided which has a mold release member that abuts on the end of the shaft member protruding from the mold from above and releases the shaft member on which the rack is formed from the upper mold.

1 Rack bar 2 Shaft member 3 Rack 4 Flattened portion 5 First opening 6 Second opening 7 Protruding portion 10 Manufacturing device 11 Mold 12 Metal core 12a Bottom surface 12b, 12c of core metal Side surface 12d of core metal Upper surface 13 Mandrel holder 14 First mandrel push rod 15 Second mandrel push rod 16 Upper mold 16a Lower surface of upper mold 17 Lower mold 17a Upper surface of lower mold 18 Rack tooth mold 18a Molding surface 20 of rack tooth mold Holder 21 Top Mold holder 22 Lower mold holder 23 Holder support frame 24 Base 25 Holding grooves 25a, 25b Holding groove side surfaces 25a1, 25b1 Holding groove side upper regions 25a2, 25b2 Holding groove side lower regions 26 Upper mold forming grooves 27 Lower mold Molding groove 28 Main cooling passage 29 Sub-cooling passage 30 Main cooling passage inlet 31 Main cooling passage outlet 32 Oil supply passage 33 Injection nozzle 34 Oil supply passage inlet 35 Upper mold lower part 35a, 35b Upper mold lower side surface 36 Upper mold upper parts 36a, 36b Upper mold upper side surface 37 Recess 38 Pressing member 39 Driving unit 40 Pressure chamber 40a First pressure chamber 40b Second pressure chamber 41 Insertion hole 42 Partition wall 43 Push rod 44 Supply/discharge device 45a, 45b Supply/discharge path 50 Protruding portion 51 of core bar Whirl-stop portion 51a Concave curved surface 52 First core metal push rod insertion portion 53 First core metal push rod tip portion 53a Convex curved surface 54 Second core metal push rod insertion portion 60 First connecting member 61 Second connecting member 62 Connecting means 63 Push rod driving part 64 First moving table 65 Second moving table 66 Driving part 70 Release mechanism 71 Release member 72 Lifting means 73 Passing part 80 Set Mechanism 81 Setting member 82 Drive unit 83 Chuck C1 Clearance C2 between the lower part of the upper die and the holding groove Clearance P1 between the upper part of the upper die and the holding groove P1 Waiting position of the second mandrel push rod P2 Set position of the second mandrel push rod

Claims (7)

A rack bar that forms a rack on the outer circumference of the shaft member by pressing a core bar into a hollow shaft member surrounded by a mold to transfer the shape of the mold to the outer circumference of the shaft member. A manufacturing device,
the mold;
a holder that holds the mold;
with
The mold is
lower mold;
an upper mold having a molding groove that forms a molding space surrounding the outer circumference of the shaft between itself and the lower mold;
including
The holder is
a movable upper mold holder that holds the upper mold;
a lower die holder having a holding groove for holding the lower die, wherein the upper die moved integrally with the upper die holder moves up and down within the holding groove;
including
When the mold is closed, the clearance between the lower part of the upper mold extending from the lower surface of the upper mold to the depth of the forming groove or more and the side surfaces on both sides in the width direction of the holding groove is smaller than the clearance between the upper part of the upper mold and the side surfaces on both sides in the width direction of the holding groove,
A pair of pressing members provided across the holding groove in the width direction of the holding groove and capable of protruding from side surfaces on both sides in the width direction of the holding groove,
The apparatus for manufacturing a rack bar, wherein the pair of pressing members protrude from both side surfaces in the width direction of the holding groove and clamp the lower portion of the upper mold when the mold is closed . The rack bar manufacturing apparatus according to claim 1,
The apparatus for manufacturing a rack bar, wherein both side surfaces in the width direction of the lower part of the upper mold project against both side surfaces in the width direction of the upper part of the upper mold. The rack bar manufacturing apparatus according to claim 1,
An apparatus for manufacturing a rack bar, wherein an upper region facing the upper portion of the upper die is recessed from a lower region facing the lower portion of the upper die on both lateral sides of the holding groove in the width direction. The rack bar manufacturing apparatus according to claim 2 or 3,
An apparatus for manufacturing a rack bar, wherein one or more recesses for holding a lubricant are provided in the lower region on both side surfaces in the width direction of the lower portion of the upper die and/or on both side surfaces in the width direction of the holding groove. . The rack bar manufacturing apparatus according to any one of claims 1 to 4,
a first core push rod inserted into the shaft member through a first opening on one axial end side of the shaft member;
a second core push rod inserted into the shaft member through a second opening on the other axial end side of the shaft member;
with
The core bar has a detent part,
The first cored bar push rod has a tip end portion that engages with the anti-rotation portion,
The distal end portion of the first core metal push rod and the anti-rotation portion of the core metal are engaged with each other, and the core metal is sandwiched between the first core metal push rod and the second core metal push rod. the mandrel is press-fitted into the shaft member by the first mandrel push rod and pushed back by the second mandrel push rod. The rack bar manufacturing apparatus according to claim 5,
a first connecting member that moves integrally with the first mandrel push rod;
a second connecting member that moves integrally with the second core push rod;
connecting means for connecting the first connecting member and the second connecting member and maintaining a state in which the cored bar is sandwiched between the first cored bar push rod and the second cored bar push rod;
a single push rod driving unit that moves the first core push rod and the second core push rod while the first connection member and the second connection member are connected;
Equipment for manufacturing a rack bar. The rack bar manufacturing apparatus according to any one of claims 1 to 6,
The mold holds the shaft member in a state in which at least one end of the shaft member protrudes outside the mold,
A rack bar having a release member that abuts from above the end of the shaft member protruding from the mold, and a release mechanism that releases the shaft member on which the rack is formed from the upper mold. manufacturing equipment.

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