JP5755358B1 - Interchangeable threading tool - Google Patents

Abstract

An inexpensive threading part exchangeable threading tool having sufficient torque transmission performance and positioning performance is proposed. A threading part replaceable threading tool according to the present invention includes a shank part, a threading part, and an intermediate collar, and a connecting structure extends along an axis of the shank part. It is comprised by the convex part 15 which exists and the recessed part 16 fitted to the convex part 15, and the outer peripheral surface of the convex part 15 and the internal peripheral surface of the recessed part 16 corresponding to this are three or more plane 15a, 16a, and plane 15a. , 16a and arc surfaces 15b, 16b centering on the axis O of the shank portion 14, and the center angles of the arc surfaces 15b, 16b are 4-12. [Selection] Figure 1

Description

  The present invention relates to a threading tool including a shank part and a threading part, such as a cutting tap and a rising tap, and more particularly to a threading part exchange type threading tool.

  A high-speed tool steel that is less likely to be worn or chipped due to repeated use of the tool is generally used for the threaded portion of the threading tool. Since high-speed tool steel is expensive, when the nominal diameter of the threaded portion is φ20 or more, the raw material cost ratio in the manufacturing cost is high, and particularly when the total length is long, the ratio becomes remarkable. For this reason, there is a need for a threaded part replaceable threading tool that can save resources and reduce costs by allowing the shank part and the threaded part to be separated.

  As one of the threading tools that can be separated into such a shank part and a threaded part, the following Non-Patent Document 1 describes that a concentricity between the shank part and the threaded part is secured through a straight shaft and a key is used. A metric thread shell tap (specified in M50 to M200) is shown, which is configured to transmit torque through the connector.

  Further, Patent Documents 1 and 2 listed below show that the threaded portion and the shank portion can be separated and the threaded portion is made of cemented carbide. Patent Document 3 discloses a high-speed tool steel threaded portion that is positioned on a shank portion by a tapered portion.

Japan Tool Manufacturers Association Standard TAS4117-1973 Metric Screw Shell Tap

JP 2006-123120 A JP 2006-123121 A JP 2010-099794 A

  By the way, in the above-mentioned shell tap, since the fitting tolerance of the straight shaft that fits the shank part and the threaded part greatly affects the coupling accuracy, the effect of heat treatment deformation of the shank part and the threaded part is eliminated, and the fitting precision is improved. Therefore, both the shaft of the shank part and the hole of the threaded part must be ground after heat treatment. For this reason, the increase in processing man-hours led to an increase in cost.

  Further, in a cutting tap having a size of M30 or more, four grooves are common, and the groove bottom diameter of the four grooves is usually about 43% to 48% of the nominal dimension. However, in the case of M30, since the groove bottom diameter of the four grooves is about φ12.9 to 14.4 mm, in the above-described shell tap structure, the shaft diameter connecting the shank portion and the threaded portion is combined. In addition, it is difficult to secure sufficient strength of the tenon key with the four grooves. Therefore, the inventor made a trial production of a threaded portion 20 having a cutting edge 20a and six grooves 20b as shown in FIGS. 9 and 10, and this threaded portion 20 is connected to the shank portion via the intermediate collar 21. When a screw hole was formed by a screw machining tool adapted to be coupled to 22, a phenomenon that the chip storage capacity was insufficient and the tenon portion 20 c was damaged was observed.

  On the other hand, the high-speed tool steel is much cheaper than the one made of cemented carbide like Patent Documents 1 and 2 (the high-speed tool steel costs about 10% of the cemented carbide). It was difficult to reduce the manufacturing cost to meet the raw material cost reduction. Further, in the case where the threaded portion made of high-speed tool steel is positioned by the tapered portion, the grinding finish after the heat treatment is required, which causes an increase in the number of processing steps, and thus there is a limit to cost reduction.

  Therefore, the present invention provides a threaded part replacement type threading tool that can replace the threaded part and reuse the shank part even when the threaded part has reached the end of its life, and has sufficient torque transmission performance and positioning performance. It aims at providing at low cost.

The present invention provides a shank portion, a threaded portion having a cutting edge for machining an internal thread, and a connecting structure provided between the shank portion and the threaded portion. An intermediate collar that detachably connects the parts,
The connection structure is composed of a convex portion extending along the axis of the shank portion and a concave portion fitted to the convex portion,
The inner peripheral surface of the outer peripheral surface and the concave portion corresponding thereto of the protrusions, Bei example three or more planes, and a circular arc surface centered on the axis of the shank portion with connecting flat faces,
The rigidity of the intermediate collar is a threaded part replaceable threading tool that is lower than the rigidity of at least one of the shank part and the threaded part .

  The number of the planes is preferably 4 or more and 8 or less.

  The threaded portion is preferably a cutting tap or a raised tap.

  The threaded portion is preferably subjected to a surface treatment on at least the cutting edge.

  The threaded portion preferably has a nominal diameter of 20 mm or more.

The threaded part replaceable threading tool of the present invention is to join the shank part and the threaded part via an intermediate collar, and in the connecting structure connecting them, the outer peripheral surface of the convex part and the concave part corresponding thereto the inner peripheral surface of the three or more planes, so are those composed of a circular arc surface centered on the axis of the shank portion with connecting plane between, it is possible to perform sufficient torque transmitted by the plane Moreover, sufficient positioning performance can be obtained by this circular arc surface , and further, for example, by appropriately selecting the material and the outer diameter, the rigidity of the intermediate collar is higher than the rigidity of at least one of the shank portion and the threaded portion. When lowering, the intermediate collar may be damaged before the threaded part is damaged, even if an abnormal increase in cutting torque may occur due to chip trouble during threading. It is, Ru can have a function of preventing damage to the workpiece.

  Therefore, according to the present invention, sufficient runout accuracy and torque transmission performance of the threaded portion relative to the shank portion can be obtained, and it can be used in the same manner as a normal integrated threading tool (tap), and the threaded portion is damaged. In some cases, the threaded part can be separated from the shank part and replaced with a new threaded part. Moreover, since these planes and arcuate surfaces can be processed relatively easily, the cost can be kept low.

Also, by using a inexpensive material as an intermediate color, it is possible to reduce the cost.

It is a front view and a partial sectional view showing one embodiment (screw processing part exchange type cutting tap) of a screw processing part exchange type threading tool according to the present invention in an assembly state. FIG. 2 is an exploded view of the threaded part exchange-type threading tool shown in FIG. 1. FIG. 3 is a front view and a side view of the threaded portion shown in FIG. 2. FIG. 3 is a cross-sectional view and a side view of the intermediate collar shown in FIG. 2. It is the front view and side view of a shank part which are shown in FIG. It is a side view of the convex part in the connection structure shown in FIG. It is a side view of the recessed part in the connection structure shown in FIG. FIG. 8 is a partially enlarged side view of part A in FIGS. 6 and 7 when the convex part in FIG. 6 and the concave part in FIG. 7 are fitted together. It is an exploded view of a 6-groove shell tap of M30 × 3.5. It is the front view and partial sectional view which show the 6 groove shell tap shown in FIG. 9 in an assembly state.

  Hereinafter, a threaded part replaceable cutting tap (hereinafter also simply referred to as a “cutting tap”), which is an embodiment of a threaded part replaceable threading tool according to the present invention, will be described in detail with reference to the drawings. 1 is a front view and a partial cross-sectional view showing the cutting tap in an assembled state, FIG. 2 is an exploded view of the cutting tap shown in FIG. 1, and FIG. 3 is a screw machining shown in FIG. 4 is a cross-sectional view and a side view of the intermediate collar shown in FIG. 2, and FIG. 5 is a front view and a side view of the shank portion shown in FIG. FIG. 7 is a side view of a convex portion in the connection structure shown in FIG. 2, FIG. 7 is a side view of a concave portion in the connection structure shown in FIG. 2, and FIG. It is the elements on larger scale in the A section of FIG. 6, FIG. In the following description, the “front end side” is the side where the threaded portion is located with respect to the shank portion, and the “rear end side” indicates the opposite side.

  In the figure, reference numeral 11 denotes a cutting tap that is an embodiment of the present invention. As shown in FIGS. 1 and 2, the cutting tap 11 includes a threaded portion 12 and a shank portion 14. The threaded portion 12 of the present embodiment is an M30 hand tap, and has a cutting edge 12a for machining a right-hand thread and four grooves 12b for accommodating chips.

  The threaded portion 12 and the shank portion 14 are coupled via the intermediate collar 13. More specifically, between the threaded portion 12 and the intermediate collar 13 and between the intermediate collar 13 and the shank portion 14, the convex portion 15 extending along the axis O of the shank portion 14 and , A connecting structure R is provided which is constituted by a concave portion 16 fitted into the convex portion 15. In the present embodiment, a convex portion 15 is provided on the rear end side of the threaded portion 12 and the front end side of the shank portion 14, and the intermediate collar 13 is provided with a concave portion 16 penetrating therethrough. Note that the recess 16 of the intermediate collar 13 does not have to penetrate. Further, the concave portion 16 may be provided in the threaded portion 12 or the shank portion 14, and the convex portion 15 may be provided in the intermediate collar 13.

The outer peripheral surface, and an inner peripheral surface of the concave portion 16 corresponding to the convex portion 15, ash comprises three or more planes, and a circular arc surface centered on the axis O of the shank portion 14 along with connecting the plane between It is. In the present embodiment, the six planes 15a and 16a are arranged in a regular hexagonal column with the axis O as the center, and the adjacent planes 15a and the planes 16a are separated by the arcuate surfaces 15b and 16b with the axis O as the center. Connected. In addition, since the planes 15a and 16a are set so that about 65% to 75% of the diameter of the shank portion 14 has a two-sided width dimension, the allowable torque between the convex portion 15 and the concave portion 16 is for screw machining. The cutting torque at the cutting tap is about four times or more, and sufficient strength is secured. In the present embodiment, the tolerance zone class of the outer diameter Da on the arc surface 15b is set to g6, and the tolerance zone class of the outer diameter Db on the arc surface 16b is set to H7. Ensuring sufficient positioning accuracy.

  Further, in the present embodiment, the convex portion 15 directly connects the flat surface 15a and the circular arc surface 15b as shown in FIG. 8, but the concave portion 16 is in contact with the circular arc surface 16b on both sides of the circular arc surface 16b and the circular arc surface 16b. Is provided with a small circular arc surface (relief) 16c having a diameter smaller than the diameter. Thereby, since the influence of the deformation | transformation which arises when transmitting torque via plane 15a, 16a does not reach circular arc surface 15b, 16b, positioning accuracy can be maintained even if it uses repeatedly. Further, the same effect can be obtained even if the arc surfaces 15b and 16b are flat.

  In the present embodiment, the convex portions 15 provided on the threaded portion 12 and the shank portion 14 are formed by performing milling before the heat treatment on the flat surface 15a and performing cylindrical grinding after the heat treatment on the circular arc surface 15b. . Since the heat treatment deformation is expected for the flat surface 15a, it is preferable to set the finished width of the two faces after the heat treatment to the tolerance zone class f9, and this accuracy is sufficiently secured by setting the milling accuracy in consideration of the heat treatment deformation amount. be able to. Further, the outer diameter Da on the circular arc surface 15b can be obtained with the accuracy of the tolerance zone class g6 by the above processing method, so that the cost required for processing can be suppressed.

  The recess 16 of the intermediate collar 13 can be formed by end milling or grinding. However, when these are used, it is necessary to use a tool having a small tool diameter when forming the vicinity of the arc surface 16b. There are difficulties in securing processing accuracy and reducing processing costs. On the other hand, when the recess 16 is formed by the wire cut electric discharge machine after the heat treatment, the tolerance zone class H7 can be secured on the entire circumference of the recess 16 including the outer diameter Db on the arc surface 16b. 13 can be formed with high accuracy and at low cost.

  Further, as shown in FIG. 3, the threaded portion 12 of the present embodiment is provided with a screw hole 12c extending from the rear end side toward the front end side along the axis O of the shank portion. Further, as shown in FIG. 5, the shank portion 14 is provided with a bolt insertion hole 14a in which the inner diameter on the rear end side is larger than the inner diameter on the front end side. Then, as shown in FIG. 2, after the threaded portion 12, the intermediate collar 13, and the shank portion 14 are combined, the coupling bolt 17 is inserted into the bolt insertion hole 14a from the rear end side of the shank portion 14, and the screw hole 12c is inserted. On the other hand, the assembly of the cutting tap 11 is completed. In this embodiment, since the cutting edge 12a processes a right-hand thread, the connecting bolt 17 is also a right-hand thread to prevent the connecting bolt 17 from loosening. For this reason, when the cutting edge 12a processes a left-hand thread, the coupling bolt 17 is also a left-hand thread. Further, the screw hole 12 c may be provided in the shank portion 14, and the bolt insertion hole 14 a may be provided in the screw machining portion 12.

  The threaded portion 12 of the present embodiment is formed of high-speed tool steel, but the intermediate collar 13 and the shank portion 14 can be formed of alloy steel for machine structure such as SCM or SNCM. Thereby, the material cost of the cutting tap 11 can be suppressed. In addition, since the rigidity of the intermediate collar 13 is lower than the rigidity of the threaded portion 12, the threaded portion 12 may be damaged even if an abnormal increase in cutting torque due to chip trouble during threading occurs. By damaging the intermediate collar 13 before starting, damage to the work material can be prevented. The same effect can be obtained when the rigidity of the intermediate collar 13 is made lower than the rigidity of the shank portion 14.

  The cutting tap 11 according to the present invention was formed with the specifications shown in Table 1, and the performance was investigated. In addition, the cutting tap of Examples 1-7 is the structure shown in FIGS. 1-8, Comprising: Japanese Industrial Standard JISB4430-1998 Annex "Hand tap for metric screw (J form)", Nippon Tool Industries It is formed in conformity with the association standard TAS4105- 1970 “equal diameter hand tap for metric coarse screw” and the Japan Tool Manufacturers Association standard TAS 4106-970 “equal diameter hand tap for metric fine screw”.

  With respect to the cutting taps thus obtained (Examples 1 to 7), the deflection of the outer diameter of the threaded portion was determined on the basis of the shaft center of the shank portion. Moreover, the cutting torque at the time of normal rotation shows the processing torque when carrying out internal thread processing to the steel plate equivalent to JIS specification S50C. Moreover, the allowable torque of a convex part is a value at the time of using the steel materials from which the tensile strength after the heat processing of a shank part becomes about 1200 MPa. Since the threaded part is made of high-speed tool steel (tensile strength after heat treatment is 2000 MPa or more), the allowable torque at the convex part of the threaded part is that of the convex part shown in Table 1. It becomes larger than the torque value.

  In the Japanese Industrial Standard JIS B 4430-1998 Annex “Hand Tap for Metric Thread (J Type)”, the deflection of the outer diameter of the threaded portion is specified to be 40 μm or less, but as shown in Table 1, Example 1 ˜7 satisfies this rule. Further, the allowable torque of the convex portions is four times or more than the processing torque during normal rotation in Examples 1 to 7. And after processing the internal thread, when the state of the convex part and the concave part was confirmed, deformation or the like was not recognized in these, and loosening of the bolt was not recognized.

  The threading part replaceable threading tool according to the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope according to the claims. For example, although the above-mentioned convex portions and concave portions are hexagonal prisms, they may be triangular prisms composed of three planes or pentagonal prisms composed of five planes. In addition, it is preferable that the plane provided in a convex part and a recessed part shall be 4 or more and 8 or less from a viewpoint of ensuring the workability and allowable torque of a convex part and a recessed part. In addition to the hand tap described above, the threaded portion is not limited to a cutting tap such as a spiral tap or a spiral point tap, and a raised tap can also be applied.

  In addition, cutting performance and durability can be improved by performing at least oxidation treatment, nitriding treatment, and surface treatment with a coating such as TiN or TiCN on the cutting edge.

  And the threading part exchange type threading tool according to the present invention is not limited to the size of the nominal diameter M30 shown in FIGS. 1 to 8 and can be applied to any size, but the ratio of the material cost to the cost is high. It is preferable to apply to a size of nominal diameter M20 or more. The size is not limited to the metric unit, but may be the inch unit.

  Moreover, H7 is an example of the tolerance zone class g6 of the outer diameter Da on the circular arc surface 15b and the tolerance zone class of the outer diameter Db on the circular arc surface 16b, and may be changed according to the required accuracy.

  And, when performing deep hole machining using the thread machining part replaceable screw machining tool according to the present invention, it can be replaced with a long shank part, and an inexpensive material can be used for the shank part. In this respect, the tool can be made inexpensive. In addition, since the threaded portion can be replaced, a plurality of threaded portions can be replaced and used for one shank portion, which contributes to resource saving.

  Further, in Table 1, as an example, the JIS standard appendix and the shan standard based on the TAS standard are described as a unified dimension. However, in the present invention, a threaded part having a plurality of nominal dimensions with respect to one shank part. Therefore, the shank part can be shared, contributing to resource saving. The threaded portion, the intermediate collar, and the shank portion can be used in various combinations. If the allowable torque between the convex portion and the concave portion is three times or more than the cutting torque, the combination is free.

  In addition, when the convex portion of the threaded portion is formed in a hexagonal prism shape as in the present embodiment, torque is transmitted using a socket wrench, so that the female screw is reworked and the tool cost is low only for the threaded portion. It is also possible to do this.

  Thus, according to the present invention, it is possible to provide a threaded portion exchange-type threading tool at a low cost and to contribute to saving of rare metals contained in the steel material of the tool.

11 Threaded part interchangeable threading tool (Threaded part interchangeable cutting tap, cutting tap)
DESCRIPTION OF SYMBOLS 12 Thread processing part 12a Cutting edge 12b Groove 12c Screw hole 13 Intermediate collar 14 Shank part 14a Bolt insertion hole 15 Convex part 15a Plane 15b Arc surface 16 Concave part 16a Plane 16b Arc surface 16c Small arc surface (escape)
17 Connecting bolt 20 Threaded portion 20a Cutting edge 20b Groove 20c Tenon portion 21 Intermediate collar 22 Shank portion O Shank axis R Connection structure

Claims (5)

The shank part and the threaded part are separated by a connecting structure provided between the shank part, a threaded part having a cutting edge for machining an internal thread, and the shank part and between the threaded parts. With an intermediate color that can be combined,
The connection structure is composed of a convex portion extending along the axis of the shank portion and a concave portion fitted to the convex portion,
The inner peripheral surface of the outer peripheral surface and the concave portion corresponding thereto of the protrusions, Bei example three or more planes, and a circular arc surface centered on the axis of the shank portion with connecting flat faces,
The threaded part exchangeable threading tool , wherein the rigidity of the intermediate collar is lower than the rigidity of at least one of the shank part and the threaded part . 2. The thread machining portion replaceable thread machining tool according to claim 1, wherein the number of the planes is 4 or more and 8 or less. The threaded part exchangeable threading tool according to claim 1 or 2 , wherein the threaded part is a cutting tap or a raised tap. The threaded part exchangeable threading tool according to any one of claims 1 to 3 , wherein the threaded part is obtained by subjecting at least the cutting edge to a surface treatment. The screw threaded part exchange type threading tool according to any one of claims 1 to 4 , wherein the threaded part has a nominal diameter of 20 mm or more.

Images