JP4703149B2 - Screw hole machining method - Google Patents

Description

  The present invention relates to a tap tool and a screw hole machining method for machining a screw hole by performing threading on the inner peripheral surface of the pilot hole simultaneously with the machining of the pilot hole.

Conventionally, when machining a threaded hole, a prepared hole having a diameter substantially the same as the desired inner diameter of the threaded hole is formed in advance on a workpiece using a drill or the like, and then the surface is lowered using a tap, a threading tool, a threading milling machine, or the like. A cut was given to the inner peripheral surface of the hole to form a thread.
In such a method, processing of the pilot hole and threading are performed separately, so it takes time to process, and tool switching is required when switching from piloting to threading, which reduces processing efficiency. I was letting.
Therefore, in order to eliminate the need for tool replacement time, a tool or a drilled tap in which a drill blade is integrally provided at the tip of a thread milling cutter has been proposed (see Patent Documents 1 and 2).

JP-A-6-39643 Japanese Patent Laid-Open No. 10-100020

  However, in the tool described in Patent Document 1, the distance from the rotation axis of the tool to the outermost end of the threaded milling blade is smaller or the same as the distance from the rotation axis of the tool to the outermost end of the drill blade. When a pilot hole is machined with a drill blade, threading with a thread milling blade cannot be performed. For this reason, after machining the pilot hole using the drill blade provided at the tip of the tool, the tool is rotated in the radial direction while rotating in the pilot hole, and the blade of the thread milling cutter is moved to the inner peripheral surface of the pilot hole. A screw thread is formed in the inner peripheral surface of a pilot hole by making it contact. Therefore, although the tool change time is not required, since the processing of the pilot hole and the threading process are performed in separate steps, even if the tool described in Patent Document 1 is used, a long time is still required for the processing of the screw hole. There was a problem that it took.

  The tool described in Patent Document 2 is formed so that the length of the tap portion is set in a range of 2 to 5 times the screw pitch, and the height of the tap blade is gradually increased toward the rear side of the tool. Yes. With this configuration, there was a problem that the complete screw could not be cut to near the bottom of the blind hole. Moreover, since the length of the tap portion is long, there is a problem that the cutting resistance is large.

  The present invention has been made in order to solve the above-mentioned problems, and the object of the present invention is to be able to simultaneously process the pilot hole and the threading process, so that the complete screw is close to the bottom of the blind hole. It is an object to provide a tapping tool having a small cutting and cutting resistance and a screw hole machining method using the same.

To achieve the aforementioned object, a shank portion, a blade portion extending from the shank portion, a drill blade provided at the tip of the blade portion, and chips formed from the drill blade toward the shank portion comprises a discharge groove, and said blade portion thread forms a thread blades projecting radially from the outer peripheral surface of between said shank portion and the drill bit, the threaded blade is provided in the tip region of the blade portion and the projecting radially beyond the outermost end of the drill bit, drill blade is provided only in the region of approximately one pitch of the helical path along a helical path corresponding to the thread to be formed A screw hole machining method in which a screw tool is machined simultaneously with drilling by sending a tap tool in the direction of the rotation axis while rotating around the rotation axis. When Each time the tap tool with a drill blade is rotated around the rotation axis in synchronism with the feed in the rotation axis direction, the screw hole is processed by advancing by the lead of the thread cutting blade in the rotation axis direction to obtain a desired depth. A threaded hole machining method is provided in which after the threaded hole is machined, the tap tool with a drill blade is rotated in a state in which the feed in the rotational axis direction of the tap tool with a drill blade is stopped .

Since the drill blade is provided at the tip of the blade portion of the tool, the workpiece can be drilled by pressing the tip of the tool against the workpiece. Therefore, it is not necessary to prepare a separate tool for machining the prepared hole. In addition, since a thread cutting blade is provided between the drill blade and the shank portion so as to protrude radially from the outer peripheral surface of the blade portion beyond the outermost end of the drill blade, In addition, threading with a thread cutting blade can be performed on the inner peripheral surface of the already drilled hole. Accordingly, simultaneously with the formation of the pilot hole, a thread can be processed on the inner peripheral surface of the hole, and the entire processing time can be greatly shortened.
Since the thread cutting blade is provided in the tip region of the blade portion and only in the region corresponding to one pitch of the spiral path corresponding to the screw thread to be formed, the screw thread is provided to the vicinity of the bottom of the hole. Can be processed. In addition, cutting resistance during threading can also be reduced.

By using the up Symbol drill bit tapped tool Thus, it is possible to process the threads at the same time drilling and.

Is rotated the tool while stopping the rotation axis direction of the feed of the tool to a Nozomu Tokoro depth after processing, the state that led to the inner peripheral surface of the prepared hole in the middle cut from the inner peripheral surface of the prepared hole by threading edge Can be completely separated from the inner peripheral surface of the pilot hole and discharged to the outside. In particular, when a thread cutting blade is provided in the tip region of the blade portion of the tool, the region where the screw thread is broken is also limited to the bottom region of the pilot hole.

  According to the present invention, the pilot hole is processed by the drill blade provided at the tip of the blade portion of the tap tool with the drill blade, and at the same time, the screw is provided on the inner peripheral surface of the pilot hole by the screw cutting blade provided thereabove. Since the crest can be machined, drilling and threading can be performed at the same time without changing tools, and the time required for machining the screw hole can be greatly reduced. Also, the complete screw can be cut to the bottom of the blind hole. Furthermore, since the thread cutting blade has only about one pitch, the cutting resistance is small.

  Hereinafter, an embodiment of a tap tool with a drill blade according to the present invention will be described with reference to the drawings. 1 is a side view of a tap tool with a drill blade according to the present invention, FIG. 2 is an enlarged view of a portion surrounded by a circle II in FIG. 1, and FIG. 3 is an explanation of a screw hole machining method using the tap tool with a drill blade in FIG. FIG.

Referring to FIGS. 1 and 2, a tapping tool 11 with a drill blade includes a substantially cylindrical shank portion 13 that is gripped by a spindle of a machine tool such as a machining center directly or via a tool holder, and a rotation axis line from the shank portion 13. And a blade portion 15 extending in the direction of 17. Further, in order to chamfer the edge of the opening portion of the screw hole machined by the tapping tool 11 with a drill blade, the transition portion between the shank portion 13 and the blade portion 15 has a transition from the blade portion 15 toward the shank portion 13. A conical chamfering blade 19 having a large diameter is formed.
A drill blade 21 for forming a pilot hole in the workpiece W is provided at the tip of the blade portion 15. The drill blade 21 is composed of two blades that extend symmetrically outward from the center of rotation of the tip surface of the blade portion 15. The drill blade 21 may be composed of one blade or three or more blades as long as it can process holes.

  Further, a complete thread-shaped thread cutting blade 23 protruding in a radial direction from the outer peripheral surface of the blade portion 15 is provided between the drill blade 21 and the shank portion 13, that is, above the drill blade 21. The thread cutting blade 23 is provided on the outer peripheral surface of the blade portion 15 along a spiral path extending at a pitch corresponding to the thread to be formed. In the embodiment shown in FIGS. 1 and 2, the thread cutting blade 23 is provided in a region corresponding to one pitch of the thread along the spiral path. The blades 23 may be provided along a spiral path in a range smaller than an area corresponding to one pitch of the thread or in an area exceeding one pitch of the thread and less than two pitches. However, to ensure the stability of the posture of the tapping tool with a drill blade during threading, to minimize the extent to which the thread of the screw hole is destroyed by idle rotation for chip disposal after threading, which will be described later In addition, it is preferable to provide the thread cutting blade 23 in a region corresponding to one pitch of the thread. In this case, in order to form a screw thread near the bottom of the pilot hole formed by the drill blade 21, the thread cutting blade 23 is formed in the tip region of the blade portion 15 as shown in FIGS. In particular, it is preferably provided close to the drill blade 21.

  The thread cutting blade 23 extends to the height exceeding the outermost end of the drill blade 21 in the radial direction of the blade portion 15. For this reason, after the pilot hole is formed by the drill blade 21 at the tip of the blade portion 15, when the tool 11 with the drill blade is advanced in the direction of the rotation axis 17, the thread cutting blade 23 is formed on the inner peripheral surface of the formed pilot hole. It reaches and contacts, and the inner peripheral surface of the pilot hole is threaded. That is, in a single process, drilling of the workpiece W and threading processing of the inner peripheral surface of the prepared hole are simultaneously performed.

  In order to discharge chips generated by cutting the workpiece W by the drill blade 21 to the outside of the hole, the blade portion 15 passes through the space between adjacent screw cutting blades along the spiral path from the drill blade 21 to the shank portion 13. Further, a chip discharge groove 25 extending to the top is formed. In the embodiment shown in FIGS. 1 and 2, the chip discharging groove 25 extends spirally at a pitch larger than that of the thread cutting blade 23, but the chip discharging groove 25 is formed in a straight line according to demand. It is also possible to form.

Next, with reference to FIG. 3, the thread hole processing method using the tap tool 11 with a drill blade shown in FIG.1 and FIG.2 is demonstrated.
First, the shank part 13 of the tap tool 11 with a drill blade is gripped and attached to the spindle of a machine tool such as a machining center. Next, as shown in FIG. 3A, by moving the main shaft in the direction of the rotation axis 17 while rotating the main shaft, the tap tool 11 with a drill blade is rotated around the rotation axis 17 while rotating in the direction of the rotation axis 17. To approach the workpiece W. Then, first, the drill blade 21 provided at the tip of the blade portion 15 of the tap tool 11 with a drill blade comes into contact with the workpiece W and drills to form a pilot hole. When the tapping tool 11 with a drill blade is further advanced in the direction of the rotation axis 17, as shown in FIG. 3 (b), a pilot hole is formed deeper by the drill blade 21 and is already formed at the same time. The thread cutting blade 23 located above the drill blade 21 reaches the inner peripheral surface of the prepared hole, and the thread cutting processing is performed on the inner peripheral surface of the prepared hole by the thread cutting blade 23. At this time, every time the tap tool 11 with a drill blade is rotated around the rotation axis 17 by synchronizing the rotation of the tap tool 11 with a drill blade around the rotation axis 17 and the feeding in the direction of the rotation axis 17, the rotation is performed in the direction of the rotation axis 17. The rotation and feed of the tapping tool 11 with a drill blade are controlled so that the lead of the thread cutting blade 23 is advanced toward the workpiece W. The chips generated by the drill blade 21 are discharged out of the pilot hole along the chip discharge grooves 25 formed on the outer periphery of the blade portion 15.

  Similarly, the tool 11 with a drill blade is further advanced to a desired depth in the direction of the rotation axis 17 while synchronizing with the rotation of the tap tool 11 with a drill blade around the rotation axis 17. At this time, since chips exist between the chip discharge groove 25 of the blade portion 15 and the inner peripheral surface of the screw hole, the chips and the blade portion 15 are increased as the processed screw hole becomes deeper. The contact area increases with increasing resistance. For this reason, if processing is continued at the same rotational speed, a large force may be applied to the tapping tool 11 with a drill blade to cause damage. In order to prevent such breakage, the drill tool so that the tapping tool 11 with a drill blade advances in the direction of the rotation axis 17 and the screw hole being processed becomes deeper so that the rotation speed decreases. The rotation of the tapping tool 11 with a blade is controlled.

  Next, as shown in FIG. 3 (c), when the drill blade 21 of the tap tool 11 with a drill blade reaches a desired depth, the chamfer formed at the transition portion between the blade portion 15 and the shank portion 13. The blade 19 contacts the edge of the opening of the formed screw hole and performs chamfering. The desired screw hole is obtained by the above process. And in order to discharge | emit the chip | tip at the bottom part of a screw hole outside, and to remove the level | step difference of a chamfering part, as shown in FIG.3 (d), as shown in FIG. In a state where the feed is stopped, the tap tool 11 with a drill blade is rotated around the rotation axis 17 by at least one rotation. As a result, the thread of the screw hole around the thread cutting blade 23 is destroyed. However, in the tap tool 11 with a drill blade of the present embodiment, the thread cutting blade 23 is provided only in the tip region of the blade portion 15. Therefore, the screw thread to be broken is limited to the one near the bottom of the screw hole.

  Next, as shown in FIG. 3 (e), the tapping tool 11 with a drill blade is retracted in the direction of the rotation axis 17 (raised in the drawing), and the tapping tool 11 with a drill blade is removed from the machined screw hole. Pull out. At this time, in order to prevent the thread formed on the inner peripheral surface of the screw hole from being damaged, the rotation around the rotation axis 17 of the tapping tool 11 with a drill blade and the feeding in the direction of the rotation axis 17 are synchronized, The rotation of the tapping tool 11 with a drill blade and the rotation of the tapping tool 11 with a drill blade so that the lead of the thread cutting blade 23 is retracted in the direction of the rotation axis 17 every time the tapping tool 11 with a drill blade is rotated around the rotation axis 17 in the opposite direction to the machining. Control the feed.

It is a side view of the tap tool with a drill blade of the present invention. FIG. 2 is an enlarged view of a portion surrounded by a circle II in FIG. 1. It is explanatory drawing of the screw hole processing method by the tap tool with a drill blade of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Tapping tool with a drill blade 13 Shank part 15 Blade part 17 Rotating axis 21 Drill blade 23 Screw cutting blade 25 Chip discharge groove

Claims (1)

A shank portion; a blade portion extending from the shank portion; a drill blade provided at a tip of the blade portion; a chip discharge groove formed from the drill blade toward the shank portion; and the shank portion; and a thread form of threaded blade projecting radially from the outer peripheral surface of the blade portion between the drill bit, the threaded blade is provided in the tip region of the blade portion, and the outermost of said drill bit A tap tool with a drill blade protruding in the radial direction beyond the outer end and provided only in a region corresponding to approximately one pitch of the spiral path along the spiral path corresponding to the thread to be formed around the rotation axis A screw hole machining method in which a screw hole is machined simultaneously with drilling by sending in the direction of the rotation axis while rotating,
Each time the tap tool with a drill blade is rotated about the rotation axis by synchronizing the rotation around the rotation axis of the tap tool with the drill blade and the feed in the rotation axis direction, the lead of the thread cutting blade is made in the rotation axis direction. Process screw holes by moving forward,
A threaded hole machining method in which, after a threaded hole is machined to a desired depth, the tap tool with a drill blade is rotated in a state where feeding in the rotation axis direction of the tap tool with a drill blade is stopped.

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