JP4148475B2 - Cross hole screw - Google Patents

Description

  The present invention is easy in dimension control, easy to secure a tightening torque, and high in productivity. Particularly, a screw with a cross hole suitable for a precision screw, a driver bit for rotating the screw, and a cross hole of the screw. Relates to a pin punch for forming

  Conventionally, in order to drive a screw that tightens or loosens a screw, various shapes of engagement holes are formed in the head of the screw to engage a driver bit, and the engagement hole is formed by a cross-shaped groove. Cross-recessed screws are widely used. The basic shape of the cross-recessed screw is determined by the JIS standard, and the JIS standard is also used for the precision screw. About the screw based on these standards, original devices are applied as necessary to the portions other than the basic shape portion, and a specially shaped cross hole may be formed as necessary. In that case, special driver bits adapted to these shapes may be used.

  Such a cross-recessed screw and a driver bit for driving the cross-shaped screw have a shape as shown in FIG. 7, for example. That is, FIG. 7 shows a cross-sectional view of the main part of FIG. 7B and a cross-sectional view of FIG. 7C using a driver bit 51 having a cross blade 52 at the tip as shown in the side view of FIG. The conventional example which rotationally drives the screw 53 with a cross hole provided with the cross hole 54 as shown in the head top view of this is shown. The shape of the cross hole 54 in the cross hole screw 53 is gradually narrowed at an angle α from the surface 56 of the head 55 toward the neck portion 57 side of the screw, and below the cross hole lower end 58 is below. A bottom 60 is formed where the bit ends do not contact.

  The engaging grooves 61 having a cross shape are connected to adjacent engaging grooves 61 by an engaging surface 65 that connects the engaging surfaces 62 of the engaging grooves 61. In many cases, the engagement surface 65 is formed of a triangular section having an inclined ridge line 64 at an equally divided position between the engagement groove 61 and the adjacent engagement groove 61. The distance between the ridge lines 64 facing each other across the center line gradually increases toward the surface of the head 55.

  The driver bit 51 as shown in FIG. 7A, which engages with the cross hole 54 and rotationally drives the cross hole screw 53, has a connection portion with the bottom portion 60 where the interval between the ridge lines 64 is particularly narrow. In this portion, this portion is brought into contact with and engaged with the cruciform blade tip 59 to give a so-called biting performance. When the rotational driving force is applied to the driver bit 51, the cross hole screw 53 that bites into the driver bit 51 in this way is applied to the engagement groove of the cross hole screw 53 from the cross blade 52 of the driver bit 51. The cross-recessed screw 53 is rotated together and screwed into a workpiece (not shown) and is removed from the workpiece.

  In the above-mentioned standard for the cross hole as described above, the tip of the cross blade of the driver bit 51 is a portion that bites into the cross hole, and the narrowest part of the opposing ridge line 64 at the connection portion between the ridge line 64 and the bottom 60 is provided. The ridge line interval B is used as a main dimensional standard. Therefore, at the time of forming the cross hole, the ridge line interval, that is, the minimum interval B between the opposing ridge lines is managed so as to be within a predetermined error range. In addition, as shown in FIG. 7, at the lower end portion 58 of each engagement groove 61 of the cross hole 54, the dimension of the gap G between the opposite engagement groove lower end portions, and the engagement groove 61 on the surface 56 of the screw head 55. The size of the distance between the opposite edges of the edge 63, that is, the distance M between the upper ends of the opposite engaging grooves is also managed.

  On the other hand, when the above-mentioned cross-recessed screw 53 is rotationally driven by the driver bit 51, for example, as shown in FIG. When the size of the driver bit 51 is selected and the cruciform blade 52 is inserted, the tip inclination angle α of the cruciform blade 52 of the driver bit 51 matches the internal inclination angle α of the cruciform hole 54, and the driver bit as described above. 51 and the cross hole lower end portion 58 substantially coincide with each other. Therefore, as shown in FIGS. 8 (a) and 8 (b), the outer peripheral portion of the front end portion 59 and the cross hole lower end portion 58 at the time of final insertion. The inner peripheral portion of the cross blade 52 is substantially in contact with each other, and each blade portion of the cross blade 52 is engaged with a slight gap L in each bit engaging groove of the cross hole.

  When tightening the cross-recessed screw 53 from this state, the driver bit 51 is rotationally driven as shown in FIG. As a result, between the blade portions of the cross blade 52 and the grooves of the cross hole 54 in which the slight gap L exists as described above, the two members rotate in contact with each other in the driving direction. During this rotation, the portion of the blade portion of the driver bit 51 where the rotational direction side ridge line portion 66 abuts against the side wall 62 of the groove of the cross hole is substantially a tapered contact with the inclination angle α. The rotating force generates a force that causes the driver bit 51 to escape from the cross hole in the direction of the angle α.

  Further, in order to prevent the driver bit 51 from slipping out, when the driver bit 51 is rotationally driven while being pressed into the cross hole 54 with a large force, particularly the most distal end portion 59 and the cross hole lower end portion 58 of the driver bit 51 are formed. The rotational driving force is concentrated while a large thrust acts on the biting portion 63 that comes into contact. Therefore, since the screw material in the vicinity of the biting portion 67 is deformed and the screw material in the vicinity of the biting portion 67 on which an excessive force is applied is driven by rotation with a large force in a state where a large frictional force is applied in this portion. The material will be damaged.

  Due to the deformation and breakage of the screw material particularly in the biting portion 67 in such a cross hole, the driver bit 51 is more easily pulled out, and if a thrust is further applied to the driver bit 51 to suppress it, the groove in the cross hole cannot be rotated. It will be damaged until This phenomenon occurs when the screw is loosened in addition to the above-described screw tightening, and it is difficult to give a rotational driving force that causes the screw to pull out against the thrust while giving a particularly large thrust. It is.

  In addition, even if the change in thrust is such that the deformation or breakage of the screw material does not occur, the force in the rotational direction changes due to the change. On the other hand, if it is set to transmit a predetermined rotational torque and perform tightening, it becomes impossible to give the set desired rotational torque.

As a countermeasure, for example, in Japanese Patent Laid-Open No. 8-145024, a horizontal step portion is provided at each edge of each bit engaging groove of the screw head, and the horizontal step portion is directed to the center portion of the screw neck portion. Each of the inclined groove portions extends, and at the bottom thereof, a substantially conical bottom surface is formed. The driver bit has a blade portion that engages in the vicinity of the horizontal step portion. There has been proposed a screw in which a vertical end wall portion having a predetermined depth is formed at each end edge portion.
JP-A-8-145042

  In the formation of the cross hole in the conventional cross hole screw, the dimension of the minimum interval B of the opposite ridge line of the cross hole is managed as described above. Since the ridge line 64 is a part connected to the bottom part 60 and is a concave part, it is difficult to measure the dimension of this part. Especially in the cross holes for precision screws with nominal diameters M1, M1.2, or S1 to S0.6, this part is very small and its measurement is extremely difficult, resulting in product errors. There was a problem of getting bigger. Further, when the gap G between the lower ends of the opposing engagement grooves and the gap M between the upper ends of the opposite engagement grooves are managed, the same problem occurs in the precision screw cross hole as described above.

  In addition, when a screw is driven by engaging a driver bit with a cross hole, the conventional cross hole screw has a cam-out as described above, and the screw material is damaged. Such a technology has been proposed. In this technology, by receiving a thrust in the screw direction of the driver bit at the horizontal step portion, a change in the rotational torque of the screw due to a change in the thrust is prevented, and the formation of the vertical end wall portion and the vertical end wall portion are adapted. By using a driver bit with a cruciform blade, the taper contact as described above is eliminated at the groove side wall portion of the cruciform blade and the cruciform hole, and a line contact parallel to the screw axis is made. Thus, it is possible to prevent the screw from coming out when the screw is driven to rotate.

  However, in the screw as described above, line contact parallel to the axis of the screw is made at the groove side wall portion of the cruciform blade and the cruciform hole, so when a rotational driving force is applied to the screw by the driver bit, Since the rotational driving force concentrates on this contact portion, the groove side wall portion of the cross hole is often deformed. When the groove side wall portion of the cross hole is deformed in this way, the inclined groove portion oriented toward the center portion receives the rotational driving force, resulting in the same problem as the conventional one shown in FIG. However, it is not an appropriate solution.

  Further, in the conventional screw with a cross hole, the dimension of the minimum interval B of the opposing ridge line of the cross hole is managed as described above, and the gap G at the lower end portion of the opposing engagement groove is opposed. Since the distance M between the upper ends of the engaging grooves was also managed, it is known as a simple method for forming a cross hole, especially in a cross hole for a precision screw having a nominal diameter of M1, M1.2, or S1 to S0.6. In the molding method using a pin punch, it is very difficult to accurately obtain the above dimensions, and the defective product rate is high, so that it is difficult to adopt.

  Therefore, the present invention makes it possible to easily manufacture an accurate screw with a cross hole in a cross hole screw, and to prevent a cam bit out of a driver bit that engages the cross hole and breakage of an engaging groove. An object of the present invention is to provide a cross-recessed screw which can be easily manufactured by a pin punch, a driver bit suitable for driving the cross-recessed screw, and a pin punch suitable for forming a cross-hole. .

In order to solve the above-mentioned problem, the cross-recessed screw according to the present invention is a cross-recessed screw in which a screw hole is formed with a groove that engages with a blade of a driver bit. A driver that is formed by a part of the spherical surface, and that the center of the cross hole is formed on the same spherical surface as the spherical surface of the bottom surface of each groove, and the outer peripheral side end surface of each groove is parallel to the screw axis and engages with the groove. A cylindrical surface that is in contact with the cylindrical surface of the outer peripheral surface of the blade of the bit, and in each of the grooves, opposite side surfaces serving as driving surfaces are formed in parallel by contacting both side surfaces of the blade of the driver bit that engages with the groove. To do.

In addition, the driver bit according to the present invention is configured to rotate the screw with a cross hole, and in the driver bit having a cross blade, the tip surface of each blade is a part of a common spherical surface , and the driver bit tip center And the outer peripheral surface of each blade is parallel to the axis of the driver bit, and the cylindrical surface of the groove outer peripheral end surface of the cross hole of the screw with which the blade engages And both sides of each of the blades are formed in parallel.

Further, the cross-recessed screw according to the present invention is a pin punch provided with a cross-shaped blade for forming a cross-shaped hole that engages a blade of a driver bit with the head of the cross-shaped hole screw, and the tip surface of each blade is Formed by a part of the common spherical surface , the driver punch tip central part is formed in a spherical surface common to the spherical surface of the tip surface of each blade, the outer peripheral surface of each blade is a cylindrical surface parallel to the axis of the pin punch , Both sides of each blade are formed in parallel.

  Regarding the cross hole of the cross hole screw according to the present invention, when the dimensions are controlled at the time of manufacture, the conventional screw is a cross hole for JIS standard screw cross hole or JIS standard cross screw standard for precision screw. There is no need to manage by the dimension B, which is the minimum dimension of the opposing inclined ridgeline, and management is performed only with the blade engagement groove width and the M dimension of the cross hole. It becomes easy to measure. Further, the Q dimension is not managed, such as the distance G between the lower ends of the opposing engaging grooves and the distance M between the upper ends of the opposing engaging grooves as in the conventional case, and the total depth of the engaging grooves. Only the T dimension is managed, and this is also very easy to manage. Furthermore, since the blade surface receiving the cross-shaped torque does not have an angle with respect to the shaft center, it is possible to reliably prevent the driver from coming out.

  The cross-recessed screw according to the present invention is formed with a cross-hole formed of a groove that engages a blade of a driver bit on the screw head for the purpose of easy dimensional control, easy manufacture, and prevention of driver cam-out. In the cross-recessed screw, the bottom surface of each groove is formed by a part of a common spherical surface, and the outer peripheral side end surface of each groove is a cylindrical surface parallel to the axis of the screw, and engages with the groove in each groove. Realized by forming the opposite side surfaces that are the drive surfaces in parallel by abutting both sides of the blade of the driver bit, forming the driver bit that drives the screw with the cross hole and the cross hole of the screw with the cross hole This is realized by using a pin punch.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a head 2 of a cross-recessed screw 1 according to the present invention and a driver bit 3 for rotationally driving the cross-recessed screw 1. The cross-recessed screw 1 has a cross hole 5 formed at the center position on the surface 4 of the head 2. Yes. As shown in FIG. 2B, the cross hole 5 is formed in a cross shape perpendicularly to the axial direction of the screw from the surface 4 of the head 2 to the depth A, as shown in FIG. As shown in FIG. 5, the center O is formed by a part of a spherical surface having a radius R, and the depth of the deepest portion of the arc-shaped cross section is T.

  Accordingly, when viewing the first blade engaging groove 6 which is one blade engaging groove of the cross hole 5, as shown in FIGS. 1B and 2, the width B on the surface 4 of the head 2 of the screw is shown. A cylindrical groove outer peripheral end surface 8 having the same width B is formed perpendicularly from the arc-shaped upper end edge 7 having a diameter D1, and the same configuration is formed from the lower end edge 10 having the circular arc shape of the groove outer peripheral end surface 8 and the width B. Thus, the first groove bottom surface 13 forming a part of the spherical surface is formed as described above over the lower end edge 10 of the groove outer peripheral end surface 8 in the third blade engaging groove 11 facing each other. Similarly, the second blade engaging groove 14 and the fourth blade engaging groove 15 facing the second blade engaging groove 15 perpendicular to the first blade engaging groove 6 and the third blade engaging groove 11 facing the first blade engaging groove 6 have the same configuration. And a second groove bottom surface 16 forming a part of a spherical surface having the same center as the first groove bottom surface 13 is formed.

  Thereby, on both sides of the first blade engaging groove 6, a first driving surface 17 that is a vertical wall surface and a second driving surface 18 that opposes the first driving surface 17 are formed in parallel. Similarly, the joint groove 11 and the fourth blade engagement groove 15 are formed so that the first drive surface and the second drive surface, which are vertical wall surfaces, face each other in parallel. In addition, with the above-described configuration, on the center side of the cross-recessed screw 1 of each blade engagement groove, the first groove bottom surface 13 and the second groove bottom surface 16 are common parts, and the spherical groove center bottom surface 20 is formed. The central part of the groove center bottom surface 17 is the deepest part of the groove and has the deepest depth T. Further, a chamfered portion 21 is formed at a ridge line portion where the first driving surface 17 forming the side surface of the first blade engaging groove 6 intersects the second driving surface 18 of the adjacent second blade engaging groove 14. Similarly, chamfered portions having the same diameter are formed at all the portions where the adjacent drive surfaces intersect.

  Specific examples of the cross hole having the above-described configuration are shown in FIGS. FIG. 3 shows an example in which a cross hole 33 is formed in the head 32 of the precision screw 31 of S0.8, and a groove serving as a common groove bottom surface of each groove bottom surface in the groove bottom surface 34 and the central portion connected thereto. The center bottom surface 35 is a part of a spherical surface with a radius R = 0.50 ± 0.05 mm, the deepest depth T of the groove is 0.25 ± 0.03 mm, and the outer peripheral side of each engaging groove is as described above. A cylindrical groove outer peripheral end surface 36 is formed, and the reference dimension of the diameter D1 of the portion where the cross groove opens to the surface 37 of the head 32 of the precision screw 31 is 0.70, and the dimensional tolerance is 0 to +0.01 mm. Yes.

  Accordingly, in the illustrated example, the depth A of the outer circumferential end surface 36 of the cylindrical groove is formed to be about 0.1 mm, but the cross groove in the present invention has various aspects other than the above dimensions. Even when designing, the cylindrical groove outer peripheral end face 36 is always formed, and the depth is appropriately set according to the thickness of the head and the shaft diameter of the screw. In the example shown in FIG. 3, the width B of each blade engaging groove is a reference dimension of 0.25 mm, the dimensional tolerance is +0.01 to 0 mm, and the radius R of the chamfered portion formed at the ridge line portion where the adjacent driving surfaces intersect. The standard dimension is 0.04 mm and the dimensional tolerance is +0.01 to 0 mm.

  The example shown in FIG. 4 is an example in which a cross hole 43 is formed in the head 42 of the M1 precision screw 41, and the groove bottom 44 and the groove center bottom 45 in the central part thereof have a radius R = 0. A part of a spherical surface of 50 ± 0.05 mm is formed, the deepest groove depth T is 0.30 ± 0.03 mm, and the cylindrical groove outer peripheral end face 46 is formed on the outer peripheral side of each engaging groove. The reference dimension of the diameter D1 of the portion where the cross groove opens to the surface 47 of the head 42 of the precision screw 41 is 0.80, and the dimensional tolerance is +0.01 to 0 mm. Thereby, in the illustrated example, the depth A of the cylindrical groove outer peripheral end face 46 is formed to be about 0.1 mm. In the example shown in FIG. 4, the width B of each blade engaging groove is set to a reference dimension of 0.28 mm, the dimensional tolerance is set to +0.01 to 0 mm, and the radius R of the chamfered portion formed at the ridge line portion where the adjacent driving surfaces intersect. In this example, the reference dimension is 0.04 mm and the dimensional tolerance is +0.01 to 0 mm.

  On the other hand, with regard to the cross hole of the cross hole screw as described above according to the present invention, when controlling the dimensions at the time of manufacture, the conventional screw is a cross hole for JIS standard screw or a cross hole standard for precision screw of JIS standard. As shown in FIG. 7C, there is no need to perform management based on the B dimension which is the minimum portion of the opposing ridge line of the cross hole. In the present invention, only the blade engagement groove width and the M dimension of the cross hole are used. Since it is managed, it becomes very easy to measure. Further, the Q dimension management such as the management of the gap G between the lower ends of the opposing engagement grooves and the gap M between the upper ends of the opposing engagement grooves is not performed as in the conventional case, and the total depth T dimension of the engagement grooves is not performed. It becomes only management and becomes very easy to manage. Further, the torque receiving surface in the cross groove does not have an angle with respect to the axis and is parallel to the axis of the screw, so that the driver can be prevented from coming out.

  On the other hand, the driver bit 3 that engages with the cross hole 5 having the above-described configuration to drive a screw is shown in a perspective view in FIG. 1 (a), and a side view in FIG. As shown in b), a plan view of the front end side is used. That is, in the arrangement state shown in FIG. 1, the driver bit 3 has a first blade 22 whose tip engages with the first blade engagement groove 6 of the cross hole 5 in the screw 1 with a cross hole, and a second blade engagement groove 14. The second blade 23 whose tip engages with the third blade 24, the third blade 24 whose tip engages with the third blade engagement groove 11, and the fourth blade 25 whose tip engages with the fourth blade engagement groove 15. A cross blade 26 is provided.

  Since each of these blades engages with each blade engaging groove having the above-described configuration, for example, in the driver bit 3 for driving the M1 precision screw shown in FIG. 4, a dimension example is shown in FIG. Thus, the width of the screw blade engaging groove of the screw corresponds to 0.28 mm and the dimensional tolerance is +0.01 to 0 mm. In .28, the dimensional tolerance is 0 to -0.01 mm. In addition, the diameter φ of each blade whose outer periphery forms a cylindrical surface corresponds to the diameter D1 of the cylindrical groove outer peripheral end surface of the screw corresponding to the standard dimension of 0.80 and the dimensional tolerance of +0.01 to 0 mm. The standard tolerance is 0.80 and the dimensional tolerance is 0 to -0.01 mm.

  At the intersection of adjacent drive surfaces of each blade of the driver bit 3, the radius R of the chamfered portion corresponding to the intersection of the screw is 0.04 mm as a reference dimension and the dimensional tolerance is +0.01 to 0 mm. Correspondingly, the standard tolerance is 0.04 mm and the dimensional tolerance is 0 to -0.01 mm. Further, the tip surface of each blade of the driver bit 3 and the central tip portion 27 connected thereto are spherical surfaces having a radius R = 0.50 ± 0.05 mm, similar to the bottom shape of the cross hole of the screw driven by the driver bit. As described above, the two can be engaged with each other depending on the size error.

  In addition, in order to easily engage the driver bit as described above in the cross hole as described above and improve the biting of both, an appropriate taper is provided on the outer peripheral portion of the blade of the driver bit where the driving force does not act. You can put it on. In the present invention, by using the driver bit as described above, the screw can be reliably rotated by being engaged with the cross hole of the cross hole screw.

  FIGS. 1A and 5 show an example of a driver bit 3 that engages with the cross hole 5 of the cross hole screw 1 and rotationally drives the screw. However, a super-hard pin punch having the same shape is used. Thus, the cross hole 5 having the above-described configuration can be formed on the surface 4 of the screw head 2. FIG. 6 shows an example of a pin punch 47 for forming the cross hole 43 of the precision screw 41 shown in FIG. 4. The screw is guided by a guide 48 and arranged downward in the figure and is firmly supported. By hitting the tip 49 of the pin punch 47 on the head, a cross hole having the same shape as the tip 49 of the pin punch 47 can be formed on the head of the screw.

  In the example shown in FIG. 6, in order to form the cross hole 5 of the precision screw 41 shown in FIG. 4, a dimension corresponding to the dimension of the cross hole 5 is provided, and the width of each blade of the pin punch 47 is a reference dimension of 0. At 28 mm, the dimensional tolerance is +0.01 to 0 mm, and the diameter φ of each blade whose outer periphery forms a cylindrical surface is the standard dimension 0.80 and the dimensional tolerance is +0.01 to 0 mm. Further, the intersection of adjacent side surfaces of each blade of the pin punch 47 has a standard dimension of 0.04 mm and a dimensional tolerance of +0.01 to 0 mm. Like the driver bit 3, it is a part of a spherical surface having a radius R = 0.50 ± 0.05 mm.

  Since the cross hole of the screw with a cross hole according to the present invention does not have an inclined portion like the conventional one, when the dimensions are controlled at the time of manufacturing as described above, the inclined ridge lines facing the cross hole like the conventional screw are opposed. It is not necessary to carry out difficult dimensional management such as management by the B dimension which is the minimum part of the screw, and only the M dimension of the blade engaging groove width of the cross hole and the nominal diameter of the screw is managed. 2 and M1, even S1 to S0.6, a very small cross hole for precision screws can be manufactured simply by striking the screw head with a super hard pin punch, which is extremely productive. Can be.

  The cross-recessed screw according to the present invention can be used as a wide range of cross-recessed screws, but can be suitably used particularly for precision screws.

It is a figure which shows the example of the screw with a cross hole by this invention, and the driver bit which drives this, (a) is a perspective view of the front-end | tip part of a driver bit, (b) is a perspective view of the head part of a cross hole screw. is there. It is explanatory drawing of the said screw with a cross hole, (a) is a top view by the side of a screw head, (b) is the same sectional drawing. It is a figure which shows the 1st example of the screw with a cross hole by this invention. It is a figure which shows the 2nd example of the screw with a cross hole by this invention. It is a figure which shows the example of the driver bit which drives the said screw with a cross hole, (a) is the side view, (b) is the bottom view. It is a figure which shows the example of the pin punch which forms the cross hole of the said cross hole screw, (a) is the side view, (b) is the bottom view. It is a figure which shows the conventional cross hole screw, (a) is a side view of the driver bit which rotationally drives the screw with the cross hole, (b) is principal part sectional drawing of a cross hole screw, (c) is a cross It is a top view by the side of the head of a screw with a hole. It is a figure which shows the effect | action of the conventional cross hole screw, (a) shows a state when a driver bit is engaged with the cross hole, (b) before driving a screw with a driver bit, (c) is a figure. It is a figure which shows a state when driving the screw with a driver bit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw with cross hole 2 Head 3 Driver bit 4 Surface 5 Cross hole 6 1st blade engagement groove 7 Upper end edge 8 Groove outer peripheral end surface 10 Lower end edge 11 Third blade engagement groove 13 First groove bottom surface 14 Second blade engagement Joint groove 15 Fourth blade engagement groove 16 Second groove bottom surface 17 First drive surface 18 Second drive surface 21 Chamfer 22 First blade 23 Second blade 24 Third blade 25 Fourth blade 26 Cross blade

Claims (3)

In the screw with a cross hole in which a cross hole consisting of a groove in which the blade of the driver bit engages is formed on the screw head,
The bottom surface of each groove is formed by a part of a common spherical surface, and the center portion of the cross hole is formed on a spherical surface common to the spherical surface of the bottom surface of each groove ,
The outer peripheral side end surface of each groove is a cylindrical surface that is parallel to the axis of the screw and is in contact with the cylindrical surface of the outer peripheral surface of the blade of the driver bit that engages with the groove ,
A cross-recessed screw characterized in that in each of the grooves, opposite side surfaces serving as driving surfaces are formed in parallel by contacting both side surfaces of a blade of a driver bit engaged with the groove. In the driver bit with a cross blade,
The tip surface of each blade is formed by a part of a common spherical surface , and the driver bit tip center portion is formed on a spherical surface common to the spherical surface of the tip surface of each blade ,
The outer peripheral surface of each blade is parallel to the axis of the driver bit, and is a cylindrical surface in contact with the cylindrical surface of the groove outer peripheral end surface of the cross hole of the screw engaged with the blade ,
A driver bit characterized in that both side surfaces of each blade are formed in parallel. In the pin punch provided with a cross blade for forming a cross hole with which the blade of the driver bit is engaged with the screw head,
The thereby formed by a part of a common spherical distal end surface of each vane, the driver punch tip center is formed on a common spherical surface with the spherical surface of the distal end surface of each blade,
The outer peripheral surface of each blade is a cylindrical surface parallel to the axis of the pin punch ,
A pin punch for forming a cross hole, wherein both side surfaces of each blade are formed in parallel.

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