JP5401667B2 - Method for manufacturing rolled screw shaft - Google Patents

Description

    The present invention relates to a rolling die capable of producing a narrow-diameter deep groove screw shaft used for a rotating shaft of an automatic door drive unit and the like, and a method for producing a deep groove rolling screw shaft having a small diameter and a radius R.

  It is generally well known that a screw shaft is manufactured by rolling. A method of manufacturing a screw shaft of a ball screw by rolling (see Patent Document 1) and screw rolling that can roll a low-cost and high-performance screw groove. A die, a manufacturing method thereof (see Patent Document 2), and the like are disclosed, and through rolling using a pair of roll dies and inserting a screw shaft material between them, is used. This thread rolling is the most common, and has the great feature and advantage that only one step is required when machining the thread groove. Compared to the grinding shaft, it is expected to greatly reduce the cost due to its high productivity. Can be manufactured.

  In this rolling process, a round bar material is inserted between two rolling dies that are arranged and rotated at a desired interval, and thread grooves are formed on the surface of the round bar material by the continuous chevron teeth of the rolling die. This is a method of forming a thread groove, and since the two rolling dies are slightly inclined with respect to the axial direction of the round bar material, the two rolling dies are rotated in the same direction to make the round bar As the material is also rotated relatively, the thread groove is formed, and the material is automatically moved in the axial direction of the round bar material.

  JP 2003-33841 A   JP 2001-300675

  The biting part of the rolling die has an inclination angle of θ1 with respect to the axial direction of the round bar material, and such a rolling die is rolled in order to gradually increase the screw depth in accordance with the inclination angle. Resistance during manufacturing can be reduced.

  In addition, when a round bar material is inserted, thread grooves are sequentially formed from the end of the material. At this time, the deeper the thread groove formed by rolling, the more plastic the pressure is generated by the rolling die. Since the amount of deformation increases, the rolling resistance generated between the die and the material increases. When the rolling resistance increases, a sudden load fluctuation occurs at the rolling machine side at the start of machining and the holding force of the material at the start of machining is increased. There is a disadvantage that the accuracy and roundness of the groove becomes unstable due to an increase in rolling resistance, and therefore there is a problem that surface peeling and bending are likely to occur especially in the case of a small diameter shaft. In the case of a rolling die, there is a problem in that if there is an edge portion, stress concentration occurs at the edge portion and the material shaft is damaged and the shape and accuracy of the thread groove are affected. The present invention has been provided for the purpose of solving such problems.

  In order to solve the various problems described above, the invention according to claim 1 is a rolling die in which the cross-sectional shape of a tooth cut at right angles to the lead angle of a helical tooth formed in a chevron on the die surface is a radius. It has a semicircular shape of R and is chamfered with a radius r between the surface of the rolling die and the chevron teeth, and when viewed from the longitudinal cross-sectional shape, the surface shape bites by θ1 with respect to the central axis of the rolling die. A chamfered portion having an angle of attachment, a parallel straight portion of a portion parallel to the central axis of the rolling die, and a relief portion having a clearance angle of θ2 with respect to the central axis of the rolling die, The edge part of the biting part which is the both ends of a tooth | gear, and the edge part of an escape part edge part are rounded. Further, in the invention according to claim 2, in addition to claim 1, the both ends of the helical tooth are chamfered at an inclination angle θ3 from the surface of the rolling die with respect to the central axis of the rolling die to form relief surfaces. The rolling die is characterized in that the outer peripheral portion of the flank is formed to be rounded. The rounding of the edge part has two purposes: never creating a stress-concentrated part in the product material during manufacture and not causing injury.

  As can be seen from the above contents, this rolling die is three-dimensionally composed of a truncated cone part, a cylindrical part, and a truncated cone part having a shaft penetrating part at the center. In addition, as shown in FIGS. 2 and 3, in this rolling die, the biting angle θ1 is generally preferably 3 ° to 15 °, and the clearance angle θ2 may be the same as θ1, but 5 ° to 15 ° is more preferable, and there is no other data on the inclination angle θ3 at both ends of the helical tooth, and it has been found that 45 ° to 60 ° is preferable as a result of trial and error. Also, when there is an edge portion, it is best to make it round.

  Further, in the invention according to claim 3, a round bar material is inserted between a pair of rolling dies having spiral teeth formed in a mountain shape with a predetermined lead angle on the die surface. In the manufacturing method of the rolling screw shaft which rolls through the thread groove which followed the outer peripheral surface, the rolling die described in Claim 1 or Claim 2 is used as the said rolling die, and a small diameter round bar raw material Is inserted, and the outer diameter of the shaft is 20 mm or less, and the outer shape of the shaft is 4 times or less than that of the deep groove of radius R. The invention according to claim 4 is a manufacturing method of a deep grooved rolled screw shaft having the following. A predetermined inclined portion is provided at least on the end portion of the small-diameter round bar material that is inserted first.

  Here, the inventor assumes an axis of φ20 mm or less as the concept of the small diameter, and the relationship between the deep groove and the small diameter is a semicircular shape having a radius R that is a cross-sectional shape perpendicular to the lead angle of the helical tooth provided on the rolling die. A deep groove R which is transferred and formed on the shaft depending on the shape thereof is called a deep groove with respect to the shaft whose outer diameter is not more than four times the radius R. For example, a groove having a round bottom with a radius R of 2.5 mm is defined as a deep groove when formed on an axis of φ10 or less.

  The inclination angle θ3 may be 90 °, but the edge portion needs to be rounded. Moreover, it is preferable that both ends on the surface of the rolling die are rounded from the viewpoint of safety. Further, in FIG. 2, when the total length of the rolling die is L, the length of the biting portion is a, the length of the parallel portion is b, and the length of the escape portion is c, the biting length bites against the total length of the rolling die. The ratio a / L occupied by the part a is preferably 20 to 40%, and the ratio b / L occupied by the parallel part b with respect to the total length L of the rolling die is preferably 30 to 40%. The ratio c / L occupied by the part c is preferably 20% or less. Generally, when L is 100%, a: b: c is preferably 40%: 40%: 20%. The numerical value of the chamfering radius r between the rolling die surface and the helical teeth is appropriately changed with respect to the groove depth of the radius R.

  As shown in FIG. 3, a rolling die for manufacturing a screw shaft with a small diameter deep groove according to the present invention has a semicircular shape in which a cross section of a tooth cut at right angles to the lead angle of a helical tooth has a radius R. The groove with the maximum depth is obtained for the groove width, and because it is semicircular, it has the effect that a uniform force is applied to the entire groove and the groove is formed. Since the chamfered portion is chamfered with a radius r, the edge portion generated at the raised portion of the groove end surface when the thread groove is originally transferred by rolling does not occur, and therefore the edge portion removal processing is not necessary. In addition, the edge part of the biting part and the end part of the escape part which are both ends of the helical tooth are rounded, so that it gently enters the processing bar at the processing start end against the round bar material having an inclined part. Therefore, surface peeling does not occur, and both end portions of the helical teeth are chamfered at an inclination angle θ3 to form flank surfaces, and the outer peripheral portion of the flank surface is formed to be rounded. If this is the case, even at the first contact at the processing start end, it will enter even more gently and will not cause surface separation or edge sag at the end of the groove. Strain is prevented, and when viewed from the cross-sectional shape in the longitudinal direction, the surface shape has a biting angle of θ1 with respect to the round bar material, so that the helical teeth gradually enter deeply and undergo plastic deformation. As the amount of the material increases gradually, it does not cause sudden load fluctuations, so it is possible to manufacture highly precise grooves and high roundness shafts even if the holding force of the material is stable and the diameter is small. is there.

  The embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of a rolling die according to a first embodiment, FIG. 2 is a diagram illustrating the configuration of a rolling die according to a second embodiment, and FIG. FIG. 4 is a diagram showing the structure related to the rolling thread cutting of the rolling die of the present invention and the round bar material, and FIG. 5 is an inclined portion at both ends of the round bar material. It is explanatory drawing of what manufactured the rolling screw shaft by providing.

  First, the structure of the rolling die of Example 1 will be described. In Example 1, as shown in FIG. 1, in the rolling die 1, the lead angle 40 [deg.] Of the helical tooth 3 formed in a chevron on the die surface 2 is formed. The cross-sectional shape of the A-A arrow view cut at right angles to the shape is a semicircular shape with a radius R = 2.5 mm as shown in FIG. 3, and between the rolling die surface 2 and the chevron teeth 3. Is chamfered with a radius r = 0.7 mm, and when viewed from the cross-sectional shape in the longitudinal direction, the biting portion 4 having a biting angle of θ1 = 3 ° with respect to the central axis of the rolling die 1 in FIG. And a parallel straight portion 5 in a portion parallel to the central axis of the rolling die 1 and a relief portion 6 having a relief angle of θ2 = 5 ° with respect to the central axis of the rolling die 1, and the spiral shape The edge part of the biting part collar part which is both ends of the tooth 3 and the escape part end part is rounded, This is a rolling die for manufacturing a double thread, in which the ratio of the butt portion to the parallel straight portion to the escape portion is 40%: 40%: 20% with respect to the entire length. As shown in FIG. When a pair of dies 1 and 1 are attached to a rolling machine and the main shaft is tilted by 1 ° and a round bar material 7 having an outer diameter of Φ10 mm is inserted between the rolling dies 1 and 1, a thread groove continuous on the outer peripheral surface of the round bar material 7 As shown in FIG. 5, it became possible to manufacture a deep grooved rolled screw shaft 8 having a round bottom with an outer diameter of Φ10 mm and a radius of 2.5 mm as shown in FIG. 5. At this time, both ends of the drum surface were tested with the edges remaining, but there was no particular problem because there was no round bar material in contact with this part, but there was also a risk of accidents such as cutting fingers at the edges. Therefore, it is desirable to provide a roundness in this portion.

  Next, the structure of the rolling die 1 of Example 2 will be described. In Example 2, as shown in FIG. 2, the lead angle 40 of the helical teeth 3 formed in a mountain shape on the die surface 2 in the rolling die 1 is shown. As shown in FIG. 3, the cross-sectional shape cut at a right angle with respect to °° has a semicircular shape with a radius R = 2.5 mm, and a radius r = 0 .0 between the rolling die surface 2 and the chevron teeth 3. When viewed from the longitudinal cross-sectional shape, the surface shape of the biting portion 4 and the rolling die 1 having a biting angle of θ1 = 3 ° with respect to the central axis of the rolling die 1 in FIG. It is composed of a parallel straight line portion 5 parallel to the central axis and a relief portion 6 having a relief angle of θ2 = 5 ° with respect to the central axis of the rolling die 1, and at both ends of the helical tooth 3. Is an inclination angle θ3 = 45 from the rolling die surface 3 with respect to the central axis of the rolling die 1. Therefore, the flank 9 is formed by chamfering each other, the outer peripheral portion of the flank 9 is rounded, and the ratio of the bite portion to the parallel straight portion to the flank portion is 40%: 40%: A rolling die 1 for manufacturing a double thread having a 20% structure. As shown in FIG. 4, a pair of the rolling dies 1 and 1 is attached to a rolling machine and the main shaft is inclined by 1 °. When a round bar material 7 having an outer diameter of Φ10 mm is inserted between 1 and 1, a continuous thread groove is rolled through the outer peripheral surface of the round bar material 7 and a radius of 2.5 mm with an axis having an outer diameter of Φ10 mm as shown in FIG. It is now possible to manufacture a deep groove rolling screw shaft 8 having a round bottom. Further, the result of comparing the shaft of Example 2 and the manufactured shaft of Example 1 was superior to that of Example 2. However, depending on the application, the shaft of Example 1 can also be used.

  In addition, the round bar material 7 is rolled by using four types of material shafts, an axis with a tip portion inclined beforehand and an axis without an inclination portion, and a rear end portion also with an axis inclined and an axis without an inclination portion. As a result of manufacturing the threaded shaft, it was found that rolling with a material having inclined portions at both ends is the best method for manufacturing a rolled threaded shaft.

Structure explanatory drawing of the rolling die of Example 1 Structure explanatory drawing of the rolling die of Example 2 Structure explanatory drawing in two peaks among the AA arrow views in FIG. 1 and FIG. Rolling thread cutting relation diagram of rolling die of this invention and round bar material Explanatory drawing of a rolled screw shaft made with an inclined part on the end face of a round bar material

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, Rolling die 2, Die surface 3, Helical tooth 4, Biting part 5, Parallel straight part 6, Relief part 7, Round bar material 8, Rolling screw shaft 9, Relief surface

Claims (3)

Insert a round bar material (7) between a pair of rolling dies (1.1) having spiral teeth (3) formed in a chevron shape with a predetermined lead angle on the die surface (2) In the manufacturing method of the rolling screw shaft that rolls through the continuous thread groove on the outer peripheral surface of the round bar material (7),
In the rolling die (1), the cross-sectional shape of the tooth (3) cut at right angles to the lead angle of the helical tooth (3) has a semicircular shape, and the surface of the rolling die (2) and The space between the semicircular teeth (3) is chamfered in an arc shape, and the surface shape is 3 ° to 15 ° with respect to the central axis of the rolling die (1) when viewed from the longitudinal cross-sectional shape. A biting portion (4) having a biting angle θ1 within a range, a parallel straight portion (5) of a portion parallel to the central axis of the rolling die (1), and the rolling die (1) lifting one relief portions a clearance angle θ2 in the range of 5 ° to 15 ° with respect to the central axis (6) because is composed, at both ends of the helical teeth (3) the rolling dies (1 Chamfering at an inclination angle θ3 within a range of 45 ° to 60 ° from the surface of the rolling die (2) with respect to the central axis of Has been flank (9) are formed,
A method for manufacturing a rolled screw shaft, wherein both end portions of the round bar material (7) are inclined over the entire region . The method for manufacturing a rolled screw shaft according to claim 1, wherein the edge portions of the flank (9) at both ends of the helical tooth (3) are rounded. The ratio of the biting part (4), the parallel straight line part (5), and the relief part (6) is 40%: 40%: 20% with respect to the total length L of the rolling die (1). A method for producing a rolled screw shaft according to claim 1 or 2 .

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