JP2006123122A - Throw-away tap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throw-away tap for reducing manufacturing cost, and improving installation accuracy, by simplifying a structure of a joining part, even when detachably constituting a screw part to a body part. <P>SOLUTION: A plurality of projection strips 33 and recessed grooves 23 are arranged on a mating face between the body part 3 and the screw part 2. Thus, the effective rupture area is sufficiently secured, and rupture of the joining part by torsional torque in processing can be surely restrained. Since its joining part structure is formed in a simple shape with a structure capable of firmly fixing the body part 3 and the screw part 2, large reduction in the manufacturing cost and a large improvement in the installation accuracy of both, can be simultaneously performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a throw-away tap, and in particular, even when a screw portion is configured to be detachable with respect to a main body portion, the structure of the joint portion is simplified to reduce the manufacturing cost and improve the mounting accuracy. It is about the throwaway tap that can be.

In general, taps are used to form female threads. Tap materials are generally made of high-speed tool steel, but in recent years, taps made of cemented carbide have become popular for the purpose of more efficient tapping and longer life. (Patent Document 1).
JP 2004-276164 A (paragraph [0012] etc.)

  However, since cemented carbide has high material costs and is difficult to process, solid type (shank integrated type) taps increase material costs and processing costs, leading to an increase in product costs as a whole tap. There was a problem. In addition, the part where the cemented carbide is required as the tap material is mainly the threaded portion. However, it is inefficient to construct the shank portion from the cemented carbide material, resulting in a waste of resources. there were.

  Thus, as a result of earnestly examining the above-mentioned problems, the present inventor can reduce the product cost by making the screw part detachable from the main body part and forming only the screw part from a cemented carbide material. I found. However, in this case, it has been found that there is a problem in that the joint portion between the main body portion and the screw portion is complicated, the manufacturing cost increases, and sufficient mounting accuracy cannot be ensured.

  The present invention has been made to solve the above-described problems. Even when the screw portion is configured to be detachable from the main body portion, the structure of the joint portion is simplified to reduce the manufacturing cost. An object of the present invention is to provide a throw-away tap capable of improving mounting accuracy.

  In order to achieve this object, a throw-away tap according to claim 1 includes a main body portion that is rotated around an axis and a screw that is attached to the tip of the main body portion and forms a female screw in a pilot hole of a workpiece. And a fastening bolt that fastens and fixes the screw portion to the main body portion, and protrudes from one surface of the mating surface of the main body portion and the screw portion, and the shaft of the one surface A plurality of ridges arranged radially and linearly with respect to the core, and a plurality of ridges provided on the other surface of the mating surface for receiving each of the ridges, corresponding to the ridges. When the screw part is provided in the main body part, the screw part is fixed to the main body part by fitting the protrusion into the groove.

  The throw-away tap according to claim 2 is the throw-away tap according to claim 1, wherein each of the protrusions and the recessed grooves has a side surface connecting a base portion and a top portion of a cross-sectional shape thereof as a tapered surface, When the threaded portion is attached to the main body, the tapered surfaces of the protrusions and the recessed grooves are in contact with each other, and between one surface and the other surface of the mating surface A predetermined gap is formed.

  A throwaway tap according to a third aspect is the throwaway tap according to the first or second aspect, wherein at least three of the protrusions and the concave grooves are arranged at substantially equal intervals in the circumferential direction.

  According to the throw away tap according to claim 1, the main body portion and the screw portion can be made of different tap materials, that is, only the screw portion can be made of cemented carbide, so Compared with a solid-type tap made of a hard alloy, there is an effect that material costs and processing costs can be reduced. Further, when the threaded portion is worn out, only the threaded portion can be replaced, so that there is an effect that the resources can be effectively used.

  In addition, a plurality of protrusions are provided on one surface of the mating surface of the main body portion and the screw portion, and a plurality of concave grooves are provided on the other surface. In the case where the screw portion is attached to the portion, there is an effect that the screw portion and the main body portion can be firmly fixed by fitting the protrusion and the concave groove. Furthermore, since the joint structure between the main body portion and the screw portion has a simple shape, it is possible to reduce the manufacturing cost and improve the mounting accuracy of both.

  That is, since a plurality of protrusions and concave grooves are arranged radially with respect to the shaft core, a sufficient effective fracture area at the joint portion between the main body portion and the screw portion is sufficiently ensured. As a result, there is an effect that the breakage of the joint due to the torsional torque during processing can be reliably suppressed.

  Further, since the ridges and the concave grooves are formed radially with respect to the shaft core, the machining amount can be reduced by the amount of bolt passage holes formed in the vicinity of the shaft core. There is an effect that it is possible to achieve reduction of

  Furthermore, since the ridges (and concave grooves) are formed in a straight line, it becomes easy to process the ridges (and concave grooves) by grinding or the like, and it is possible to reduce the processing cost. Thus, since the dimensional tolerance can be further reduced, there is an effect that the main body portion and the screw portion can be fitted to each other with higher accuracy and the mounting accuracy of both can be improved.

  In addition, as described above, by forming the protrusions and the concave grooves radially and linearly, the joint structure of the main body portion and the screw portion can be greatly simplified. Can be fitted to each other with higher accuracy, and these press moldings can be facilitated, and the manufacturing cost can be greatly reduced.

  According to the throw-away tap according to claim 2, in addition to the effect produced by the throw-away tap according to claim 1, each protrusion and each concave groove has a tapered side surface connecting the cross-sectional base portion and the top portion. When the screw part is attached to the main body part, the taper surfaces of each protrusion and each groove are in contact with each other, so the contact area between the protrusion and the groove is enlarged, Accordingly, there is an effect that the main body portion and the screw portion can be more firmly fixed.

  Furthermore, in this case, a predetermined gap is formed between one surface of the mating surfaces and the other surface. Therefore, since only the tapered surfaces of the ridges and the concave grooves are used as joint portions, the centripetality can be improved, so that there is an effect that the accuracy of attaching the screw portion to the main body portion can be improved.

  According to the throw-away tap according to claim 3, in addition to the effect produced by the throw-away tap according to claim 1 or 2, the ridges and the concave grooves are arranged at substantially equal intervals in the circumferential direction. There is an effect that the load at the time of processing acting on the ridge and the concave groove can be made uniform to improve the durability.

  Here, when two ridges (and concave grooves) are arranged at substantially equal intervals in the circumferential direction (that is, 180 ° intervals), both the ridges (and concave grooves) are arranged linearly. Therefore, the fastening bolt restricts relative movement between the main body portion and the screw portion with respect to the linear direction. As a result, the load on the fastening bolt increases, but if the fastening bolt is made larger in diameter, the joint area (that is, the effective fracture area) of the ridge and the groove is reduced correspondingly, and the fracture strength against torsion torque is reduced. Cause a decline.

  On the other hand, in the present invention, since at least three protrusions and concave grooves are provided, relative movement in the linear direction can be effectively prevented, and the load on the fastening bolt can be reduced. Therefore, since it is possible to suppress the increase in diameter of the fastening bolt and to ensure a sufficient effective breaking area, it is possible to improve the breaking strength against torsional torque.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. FIG. 1 is an exploded view of the throw-away tap 1 according to the first embodiment of the present invention. (A), (b), and (c) are front views of the screw portion 2, the main body portion 3, and the fastening bolt 4, respectively. FIG. In addition, illustration of the axial direction length of the main-body part 3 is abbreviate | omitted in FIG.1 (b).

  First, the overall configuration of the throw-away tap 1 will be described with reference to FIG. The throwaway tap 1 includes a screw part 2, a main body part 3 to which the male screw part 2 is attached, and a fastening bolt 4 for fastening and fixing the screw part 2 to the main body part 3. The threaded portion 2 forms a female thread in the prepared hole of the workpiece by the rotational force of the processing machine transmitted through a holder (not shown) to be held and the feed matching the lead of the screw.

  According to the throw-away tap 1 of the present invention, since the screw portion 2 and the main body portion 3 are configured to be detachable, the screw portion 2 and the main body portion 3 are made of different tap materials, that is, the screw portion 2. Since only the cemented carbide can be used, material cost and processing cost can be reduced. Further, when the threaded portion 2 is worn out, only the threaded portion 2 can be replaced, so that the resources can be effectively used.

  Further, in the throw-away tap 1 of the present invention, the protrusion 33 and the concave groove 23 are formed in a radial straight line on the mating surface of the screw portion 2 and the main body portion 3, and these are joined to the screw portion 2 and the main body portion 3. By making it a part, the joint structure is simplified, and a reduction in manufacturing cost and an improvement in mounting accuracy are achieved at the same time.

  As described above, the screw portion 2 is a portion for cutting the surface layer portion while screwing through the prepared hole of the workpiece to form a female screw, and has a cutting edge 21 and an oil groove (see FIG. (Not shown) is engraved. The cutting edge 21 is formed with a bite portion, a complete peak portion, and a relief portion in order from the tip side (left side in FIG. 1A). In addition, the screw part 2 is comprised from the cemented carbide alloy as mentioned above.

  In the present embodiment, the case where the throwaway tap 1 is configured as a cutting tap will be described. However, the present invention is not necessarily limited to this, and the throwaway tap 1 is used as a raised tap that forms a female thread by plastic working. It may be configured.

  Similarly, the number and shape of the oil grooves are not particularly limited, and can be appropriately changed according to the nominal diameter of the throw-away tap 1. Further, the throwaway tap 1 may be configured as a grooveless tap.

  As shown in FIG. 1A, a bolt passage hole 22 is formed through the screw core 2 along the axis O. The bolt passage hole 22 is a through hole for inserting a fastening bolt 4 described later, and includes a tapered portion and a straight portion. The tapered portion is a tapered hole corresponding to the head seating surface of the fastening bolt 4.

  A plurality of concave grooves 23 are provided on the rear end surface of the screw portion 2 (the right side surface in FIG. 1A). The concave groove 23 is a portion to be a joint portion with the main body portion 3 and is configured as a concave portion having a substantially V-shaped cross section. The detailed configuration of the concave groove 23 will be described later.

  As shown in FIG. 1 (b), the main body 3 is formed in a substantially cylindrical shape having an axis O, and a fastening bolt 4 (to be described later) is provided on the tip surface (left side surface in FIG. 1 (b)). A bolt fastening hole 31 to be screwed is recessed along the axis O. In addition, the main-body part 3 is comprised from the high speed tool steel.

  A plurality of protrusions 33 are extended on the front end surface of the main body 3 (the left side surface in FIG. 1B). The protrusion 33 is a portion that becomes a joint portion with the screw portion 2, and is configured as a convex portion having a substantially V-shaped cross section so as to be able to fit into the concave groove 23 described above. The detailed configuration of the protrusion 33 will be described later.

  As described above, the fastening bolt 4 is a bolt for fastening and fixing the screw portion 2 to the main body portion 3, and is screwed into the bolt fastening hole 31 of the main body portion 3 while being inserted into the bolt passage hole 22 of the screw portion 2. As a result, the screw part 2 is fastened and fixed to the main body part 3. In addition, as shown in FIG.1 (c), as for the fastening bolt 4, the seat surface of the head (dish) is formed in the cone shape.

  Next, the screw portion 2 will be described with reference to FIG. 2A is a rear end view of the threaded portion 2 viewed from the direction of arrow Y in FIG. 1, and FIG. 2B is a cross-sectional view of the threaded portion 2 taken along line IIb-IIb in FIG. It is.

  As shown in FIG. 2, three concave grooves 23 are extended in a radial straight line with respect to the axis O on the rear end surface (matching surface) of the screw portion 2. The concave groove 23 is a portion that is fitted with a protrusion 33 (see FIG. 3) of the main body 3 described later, and is configured as a concave portion having a substantially V-shaped cross section perpendicular to the extending direction. That is, the side surface which connects the base part (bottom part) and the top part (opening part) of the ditch | groove 23 is comprised as a taper surface.

  In addition, the rear end surface (matching surface) of the screw part 2 is formed as a surface orthogonal to the axis O. Further, as shown in FIG. 2A, the concave grooves 23 are respectively arranged on three virtual straight lines passing through the axis O, and at substantially equal intervals in the circumferential direction (120 ° intervals). It is arranged. Further, the taper angle (angle formed by both side surfaces) of each concave groove 23 is set to 90 ° in the present embodiment.

  Thus, since the groove 23 is formed radially with respect to the axis O, the amount of processing for forming the groove 23 by the amount corresponding to the bolt passage hole 22 can be reduced, and as a result. The manufacturing cost can be reduced.

  In addition, since the groove 23 is linearly extended, the processing by grinding or the like is facilitated, the processing cost can be reduced, and the dimensional tolerance can be further reduced due to this. Therefore, the main body part 3 and the screw part 2 can be fitted to each other with higher accuracy, and the mounting accuracy of both can be improved.

  Next, the main body 3 will be described with reference to FIG. 3A is a front end view of the main body 3 viewed from the direction of the arrow X in FIG. 1, and FIG. 3B is a cross-sectional view of the main body 3 taken along line IIIb-IIIb in FIG. It is.

  As shown in FIG. 3, three protrusions 33 are provided on the distal end surface (matching surface) of the main body 3 so as to extend in a radial straight line with respect to the axis O. The ridge 33 is a part fitted with the concave groove 23 (see FIG. 2) of the screw part 2 described above, and is configured as a convex part having a substantially V-shaped cross-section perpendicular to the extending direction. . That is, as for the protrusion 33, the side surface which connects the base part and the top part is comprised as a taper surface.

  Note that the front end surface (matching surface) of the main body 3 is formed as a surface orthogonal to the axis O. Further, as shown in FIG. 3A, the protrusions 33 are respectively arranged on three virtual straight lines passing through the axis O and at substantially equal intervals in the circumferential direction (120 ° intervals). It is arranged. Further, the taper angle (angle formed by both side surfaces) of each protrusion 33 is set to 90 ° corresponding to the groove 23 of the screw portion 2 described above.

  Thus, since the protrusions 33 are formed radially with respect to the axis O, the protrusions 33 are provided so as to protrude by the bolt fastening holes 31 as in the case of the concave grooves 23 described above. The amount of processing can be reduced, and as a result, the manufacturing cost can be reduced.

  Moreover, since the protrusion 33 is extended linearly, like the case of the above-mentioned concave groove 23, processing by grinding etc. becomes easy and it can aim at reduction of processing cost, and it originates in this. Since the dimensional tolerance can be further reduced, the main body portion 3 and the screw portion 2 can be fitted with higher accuracy, and the mounting accuracy of both can be improved.

  Here, the top of the protrusion 33 is piled up, and the width (the vertical dimension in FIG. 4) on the base side (for example, the right side in FIG. 4) is on the opening side (the right side in FIG. 4) of the groove 23. It is configured to be larger (wider) than the width dimension (vertical dimension in FIG. 4).

  Therefore, when the screw part 2 is attached to the main body part 3, a gap is formed between the bottom part of the concave groove 23 and the top part of the protrusion 33, and the rear end surface (mating surface) of the screw part 2 and A gap is formed between the front end surface (matching surface) of the main body 3 (see FIG. 4).

  Next, the assembled state of the throw-away tap 1 will be described with reference to FIG. FIG. 4 is a partially enlarged cross-sectional view of the throw-away tap 1 schematically showing the joint portion between the main body portion 3 and the screw portion 2. 4 corresponds to a cross-sectional view of the throw-away tap 1 taken along the line IV-IV in FIGS. 2 (a) and 3 (a).

  For assembling the throw-away tap 1, first, the rear end surface of the screw portion 2 is attached to the front end surface of the main body portion 3. Thereby, as shown in FIG. 4, the groove 23 and the protrusion 33 are fitted. Next, the screw portion 2 is fastened and fixed to the main body portion 3 by the fastening bolt 4 (see FIG. 1), and the assembly of the throw-away tap 1 is completed.

  In this case, since the side surfaces of the concave groove 33 and the ridge 23 are configured as tapered surfaces, when the screw portion 2 is attached to the main body portion 3, as shown in FIG. 23 and the taper surfaces of the ridge 33 can be brought into contact with each other. As a result, the contact area between the protrusion 33 and the concave groove 23 can be expanded, and the main body 3 and the screw 2 can be more firmly fixed.

  Further, in this case, as shown in FIG. 4, a predetermined gap is formed between the front end surface of the main body portion 3 and the rear end surface of the screw portion 2. Therefore, since only the taper surfaces of the ridge 33 and the concave groove 23 can be used as joint portions, centripetal improvement can be achieved, so that the accuracy of attaching the screw portion 2 to the main body portion 3 can be improved.

  As described above, according to the throw-away tap 1 of the first embodiment, since the plurality of protrusions 33 and the recessed grooves 23 are provided on the mating surface of the main body 3 and the screw 2, When the screw portion 2 is attached, the screw portion 2 and the main body portion 3 can be firmly fixed by securing the effective fracture area by the fitting of the protrusion 33 and the concave groove 23. It is possible to reliably suppress the breakage of the joint due to the torsional torque at the time.

  Furthermore, although the structure that can firmly fix the main body part 3 and the screw part 2 has a simple shape, the joint structure has a simple shape, so that the manufacturing cost can be greatly reduced and the mounting accuracy of both can be greatly improved. It can be done at the same time.

  That is, since the protrusion 33 and the concave groove 23 are configured in a radial straight line, the joint structure between the main body 3 and the screw portion 2 can be greatly simplified. Can be fitted to each other with higher accuracy, and these press moldings can be facilitated, and the manufacturing cost can be greatly reduced.

  Next, a second embodiment will be described with reference to FIGS. In the first embodiment, the case where the protrusions 33 and the concave grooves 23 are configured to have a substantially V-shaped cross section has been described. However, in the second embodiment, the protrusions 133 and the concave grooves 123 are configured to have a substantially rectangular cross section. Has been. In addition, the same code | symbol is attached | subjected to the part same as above-described 1st Embodiment, and the description is abbreviate | omitted.

  FIGS. 5A and 5B are a rear end view and a front end view of the screw portion 102 and the main body portion 103 in the second embodiment, and correspond to the views in the directions of arrows Y and X in FIG. 1A, respectively. To do. FIG. 6 is a partial enlarged cross-sectional view of the throw-away tap schematically showing the joint portion between the main body portion 103 and the screw portion 102.

  As shown in FIG. 5, the groove 123 and the protrusion 133 have a substantially rectangular cross-section perpendicular to the extending direction, and the side surface and the protrusion that connect the bottom of the groove 123 and the opening. A side surface connecting the base portion and the top portion of the strip 133 is formed in parallel to the axis O in consideration of workability.

  Here, the depth dimension of the concave groove 133 is larger (deeper) than the height dimension of the protrusion 123. Therefore, when the screw portion 102 is attached to the main body portion 103, unlike the case of the first embodiment (see FIG. 4), the rear end surface of the screw portion 102 and the front end surface of the main body portion 1033 are in contact with each other. Be touched.

  However, the depth dimension of the concave groove 133 is configured to be smaller (shallow) than the height dimension of the ridge 123, and the top of the ridge 123 is brought into contact with the bottom of the concave groove 133 (the screw portion 102). A gap may be formed between the rear end surface and the front end surface of the main body 103.

  In addition, the arrangement | positioning number of the ditch | groove 123 and the protrusion 133 is not specifically limited, It can change suitably according to the nominal diameter etc. of a throw away tap. However, for the same reason as in the case of the first embodiment described above, it is preferable to arrange at least three at regular intervals in the circumferential direction.

  As described above, according to the throw-away tap of the second embodiment, the engagement between the protrusion 133 and the concave groove 123 ensures a sufficient effective breaking area, and the screw portion 102 and the main body portion 103 are connected. It can fix firmly and can suppress the fracture | rupture of the junction part by the twisting torque at the time of a process reliably.

  Furthermore, although the structure that can firmly fix the main body portion 103 and the screw portion 102, the joint structure is a simple shape, so that the manufacturing cost can be greatly reduced and the mounting accuracy of both can be greatly improved. It can be done at the same time.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. Can be easily guessed.

  For example, in each of the above-described embodiments, the case where the screw portions 2 and 102 are made of cemented carbide and the main body portions 3 and 103 are made of high-speed tool steel has been described, but the present invention is not necessarily limited thereto. For example, the screw part 2,102 may be made of high-speed tool steel, and the main body part 3,103 may be made of alloy tool steel.

It is an exploded view of the throw away tap in 1st Embodiment of this invention, (a), (b) and (c) are the front views of a thread part, a main-body part, and a fastening bolt, respectively. (A) is a rear end view of the threaded portion viewed from the direction of the arrow Y in FIG. 1, and (b) is a cross-sectional view of the threaded portion taken along the line IIb-IIb in FIG. 2 (a). (A) is a front end view of the main body viewed from the direction of arrow X in FIG. 1, and (b) is a cross-sectional view of the main body taken along the line IIIb-IIIb in FIG. 3 (a). It is the elements on larger scale of the throw away tap which showed typically the joined part of a main-body part and a screw part. (A) And (b) is a rear end face figure and a front end face figure of a screw part and a main part in a 2nd embodiment. It is the elements on larger scale of the throw away tap which showed typically the joined part of a main-body part and a screw part.

Explanation of symbols

1 Throw Away Tap 2,102 Threaded portion 23, 123 Projection 324 Notch (part of rotation restricting means)
3,103 Body 33, 133 Groove 4 Fastening bolt O Shaft core

Claims (3)

A main body rotated about the axis, a screw part attached to the tip of the main body part to form a female screw in a prepared hole of the workpiece, and a fastening bolt for fastening and fixing the screw part to the main body part In the provided throwaway tap,
A plurality of ridges that are provided on one surface of the mating surface of the main body portion and the screw portion and are arranged radially and linearly with respect to the axis of the one surface, and each of the ridges. A plurality of concave grooves formed on the other surface of the mating surface for receiving the concave portions corresponding to the protrusions;
When the screw part is attached to the main body part, the thread part is fixed with respect to the main body part by fitting the protrusion with a concave groove. Each of the protrusions and the grooves has a side surface connecting the base and the top of the cross-sectional shape formed as a tapered surface,
When the threaded portion is attached to the main body, the tapered surfaces of the protrusions and the recessed grooves are in contact with each other, and between the one surface and the other surface of the mating surface. The throwaway tap according to claim 1, wherein a predetermined gap is formed.   The throw-away tap according to claim 1 or 2, wherein at least three of the protrusions and the concave grooves are arranged at substantially equal intervals in the circumferential direction.

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