JP4344880B2 - Tap holder with axial micro-slide mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tap holder for mounting a tap on a machine tool provided with a tap synchronous feed mechanism, and more particularly to a rolled tap holder for machining a small diameter screw.
[0002]
[Prior art]
A collet chuck holder is used when performing conventional screw machining. As shown in FIG. 5, the collet chuck 11 is fitted to a holding portion 27 at the tip of the shank 1 that is detachably attached to the spindle 30 of the machine tool. The small diameter rolling tap 2 was inserted into the collet chuck, and the clamping nut 10 was screwed to hold it.
[0003]
Such a tap holder that holds and holds the rolling tap 2 is generally used in a machining center or the like, but no particular problem occurs in a tap size (M2 or larger) that is normally used. However, there has been a problem when machining a small diameter (equivalent to M2 or less equivalent to M1) screw on a difficult-to-cut material workpiece or the like.
[0004]
When such a small diameter rolling tap is used, since the diameter is small, normal rotation and reverse rotation are repeated at a higher speed than normal processing conditions. Also, the cutting force is increased. Since such a phenomenon occurs, the spindle feed accuracy tends to temporarily decrease during the tap synchronous feed machining. Due to this spindle feed error, an unexpected axial load is applied to the tap in the middle of machining, and as a result, phenomena such as excessive bulging of the thread on the workpiece and flaking of the thread slope occur. Machining accuracy decreases.
[0005]
In many cases, tapping is performed in a final process in which a large amount of processing is performed on a workpiece, and the occurrence of processing defects at this stage causes great damage in both material costs and processing costs. In particular, it has been a big problem in small diameter tapping of timepiece parts that are difficult to cut with precision machining. In order to prevent this, a tap holder that absorbs the spindle feed error has been desired.
[0006]
Also, since the structure of the conventional tap holder is a fixed type, there is a problem that the load is often applied at the moment when the rolling tap gets stuck in the prepared work hole, and there is a problem such as breakage at that time, This was a cause of shortening the life of the rolling tap.
[0007]
In addition, since a tap structure with a large diameter is required in order to obtain a tap structure with a high gripping force, there is a problem in that interference between a workpiece and a tool occurs particularly in processing of a small diameter tap. For this reason, there has been a demand for a roll tap holder that is small (small diameter) suitable for a small diameter roll tap of M2 or less and can absorb a spindle feed error.
[0008]
[Patent Document 1]
JP-A-6-270016 (3rd, 4th, 5th pages, Fig. 1)
[Patent Document 2]
Japanese Patent Laid-Open No. 7-285026 (2nd, 3rd, 4th pages, FIG. 1)
[Patent Document 3]
JP-A-8-108317 (pages 3, 4 and 1)
[0009]
[Problems to be solved by the invention]
The present invention has been made in consideration of such problems, and an object of the present invention is to provide a rolling tap holder used for machining a small-diameter screw on a difficult-to-cut material workpiece using a machining center with a built-in tap synchronous feed mechanism.
[0010]
In particular, to provide a mechanism that can prevent deterioration of tap synchronous feed accuracy (variation) even under high-speed and high cutting force machining conditions, and prevent over-rolling (excessive thread swelling and thread slope flaking). Is an issue.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, a tap holder having an axial micro-sliding mechanism according to the first aspect of the present invention holds a shank that is detachably mounted on a main spindle of a machine tool having a tap synchronous feed mechanism, and a rolling tap. The collet chuck is detachably attached to the tip, and is disposed between the shank and the tap holder body, and the tap holder body inserted in the shank so as to be slidable in the axial direction. And a first spring and a second spring for stopping the tap holder main body at a position where the biasing force is balanced, and extending in the axial direction to the tap holder main body. While a shaft member is attached, a spring receiving member extending in the axial direction is provided in the shank so as to be movable in the axial direction, and the second spring is provided with the bar. The tap holder body is urged in the direction of the rolling tap through a receiving member, and the tap holder body is rolled through the shaft member in a state where the first spring is supported by the spring receiving member. The tap holder body is energized in the opposite direction to the tap, and when the spindle feed error occurs during tapping and the feed amount and the tap pitch do not match, the tap holder body comes from the rolled tap attached to the tip. It is characterized by micro-sliding in a direction that matches the tap pitch in response to an external force.
[0012]
According to this invention, since the tap holder main body is stopped at the position where the urging forces of the first spring and the second spring are balanced, an unexpected axial load is applied to the tap being processed. The tap holder body can be slid slightly in the direction matching the tap pitch to prevent over-rolling of the thread. In particular, in tapping with small diameters (M2 or less) for difficult-to-cut materials, even under high-speed rotation and high cutting force processing conditions, processing defects such as excessive thread swelling due to over-rolling and flaking of the thread slope are caused. Can be eliminated.
In addition, according to the present invention, the first spring that extends by receiving the external force from the tap and the second spring that contracts by receiving the external force from the tap are provided, so that the tap can be slid in the axial direction. The holder body can be stopped. In addition, the tap holder body is slid in response to the load applied before and after the unexpected axial direction applied in each process of tapping (forward rotation), completion stop, tap removal (reverse rotation), and the rolled tap has already been formed. It can be operated to follow the thread that has been made.
Further, since the spring receiving member is movable, the holding mechanism can be simplified.
[0013]
Invention of Claim 2 is invention of Claim 1, Comprising: While sliding to the axial direction of a tap holder main body is guided between a shank and a tap holder main body, rotation of a shank is transmitted to a tap holder main body An engaging member is provided.
[0014]
According to the present invention, the rotation of the shank can be accurately transmitted to the tap holder body, and can be held slidably in the axial direction.
[0015]
A third aspect of the present invention is the second aspect of the present invention, wherein the engaging member includes a guide slot formed in the shank so as to extend in the axial direction, and a tap holder at a position facing the guide slot. A concave portion formed in the main body, and a ball for engaging the shank and the tap holder main body in a state where the guide elongated hole is prevented from coming off across the concave portion.
[0016]
According to this invention, since the engaging member is constituted by the ball straddling the shank and the tap holder main body, it is robust and can smoothly slide. Further, since the configuration is simple, the entire tap holder can be formed with a small diameter.
(0017 and 0018 are deleted. 0019 is integrated with 0011, 0020 is integrated with 0012)
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below.
Figure 1 is Ri sectional view der of an embodiment of a tap holder with axial micro slide mechanism of the present invention, FIG. 2 is a partially enlarged sectional view of a main part of FIG.
[0018]
1 has a shank 1 detachably mounted on a spindle 30 of a machine tool having a tap synchronous feed mechanism and a collet chuck 11 holding a rolling tap 2 at the tip. The tap holder body 3 is detachably attached and is inserted in the shank 1 so as to be slidable in the axial direction. The tap holder body 3 is disposed between the shank 1 and the tap holder body 3. The first spring 4 and the second spring 5 are provided so as to urge the tap holder body 3 to a position where the urging force is balanced by urging in the direction in which the urging force is balanced.
[0019]
With such a configuration, the tap holder body 3 reacts to external force from the rolling tap 2 attached to the tip when a spindle feed error occurs during tapping and the feed amount and the tap pitch do not match. And slide it in the direction to match the tap pitch.
[0020]
In FIG. 1, the tip portion of the tap holder body 3 is an inclined holding portion 27 into which the collet chuck 11 is inserted, and a tightening nut 10 is attached to a screw formed on the outer peripheral portion of the tip portion to reduce the diameter of the tap holder body 3. It is comprised so that the tap 2 can be hold | gripped.
[0021]
On the outer periphery of the shank 1, a cover 8 constituting an engaging member described later is supported by a ring 14 and is fitted into the shank 1.
[0022]
First, the configuration of the engaging member that guides the sliding of the tap holder body 3 in the axial direction between the shank 1 and the tap holder body 3 and transmits the rotation of the shank 1 to the tap holder body 3 will be described. .
[0023]
The engaging member includes a guide slot 20 formed in the shank 1 so as to extend in the axial direction, a recess 21 formed in the tap holder body at a position facing the guide slot 20, and a guide. A ball 12 that engages the shank and the tap holder body with the long hole 20 straddling the recess 21 and a cover provided on the outer periphery of the shank 1 to prevent the ball 12 from coming off so as to close the long hole 20 for guiding the shank. 8.
[0024]
The guide holes 20 provided in the shank 1 are provided at three locations at 120 degree intervals that divide the circumference into three equal parts.
When the shank 1 rotates, the ball 12 having at least a hemisphere in the guide slot 20 transmits the rotation to the concave portion of the opposing tap holder body 3. Further, since the ball 12 can freely move in the guide slot 20 in the axial direction, the tap holder body 3 can slide in the axial direction while rotating.
[0025]
Next, in the micro slide mechanism of the present invention, the axially extending shaft member 26 is attached to the tap holder body 3, while the axially extending spring receiving member 25 is provided in the shank 1 so as to be movable in the axial direction. The second spring 5 urges the tap holder body 3 in the direction of the rolling tap 2 via the spring receiving member 25, and the first spring 4 is tapped via the shaft member 26 while being supported by the spring receiving member 25. The holder body 3 is biased in the direction opposite to the rolling tap 2.
[0026]
Here, the shaft member 26 is in the form of a stepped bolt, and is attached to the tap holder body 3 with its tip screwed.
[0027]
The spring receiving member 25 is placed on the collar 15 fixed to the shank 1 with set screws 16 and 17, and the lower part is in contact with the tap holder body 3, and the spring receiving member 25 is located between the outer step and the shank 1. The second spring 5 is inserted through the washer 18 and biased in the direction of the rolling tap 2. As a result, the tap holder main body 3 in contact with the spring receiving member 25 is urged in the direction of the rolling tap 2.
[0028]
On the other hand, the first spring 4 is inserted into a cylinder in which the spring receiving member 25 extends in the axial direction, supported by a step portion inside the cylinder, and the head of the shaft member 26 fixed to the tap holder body 3. The portion is biased in the direction opposite to the rolling tap 2, and as a result, the tap holder body 3 is biased in the direction opposite to the rolling tap 2. With such a configuration, the tap holder body 3 is stopped at a position where the urging forces of the first spring 4 and the second spring 5 are balanced.
[0029]
In this stopped state, a space 23 and a minute clearance 24 are formed between the shank 1 and the tap holder body 3 and between the spring receiving member 25 and the shaft member 26 .
[0030]
Since the tap holder body 3 is tapped in such a manner that the tap holder body 3 is slidable in the axial direction, when an unexpected axial load is applied to the tap 2 in the middle of the machining, the tap holder body 3 moves to the pitch of the tap. It is possible to prevent the thread from over-rolling by micro-sliding in the direction matched with.
[0031]
Next, the result of measuring and comparing the thread using the conventional rolled tap holder and the thread using the tap holder equipped with the axial micro slide mechanism of the present invention will be described.
[0032]
FIG. 4A is an enlarged cross-sectional view of a screw thread when a small diameter tapping is performed with a conventional rolling tap holder. From this cross-sectional view, it can be seen that the thread bulges too much due to over rolling. On the other hand, (b) is a sectional view showing a normal rolled thread shape.
[0033]
FIG. 5 is a cross-sectional measurement diagram of a thread where an over-rolling failure has occurred. The processing conditions at this time are
Tap name Rolling tap M1 × 0.25
Work material SUS410
Rotational speed (min) 955
Cutting speed (m / min) 3.0
Feed rate (m / min) 238.8
Pilot hole diameter 0.89
Holder Collet chuck holder.
From this measurement diagram, it can be seen that the angle of intersection is narrower than the normal thread angle (60 degrees). In addition, although the screw thread is close to a normal screw thread shape, the thread slope is lightly peeled on the entrance side, resulting in poor screw accuracy.
[0034]
FIG. 6 is a measurement diagram of a cut surface of a thread where an over-rolling failure has occurred under processing conditions different from those in FIG. The processing conditions at this time are
Tap name Rolling tap M1 × 0.25
Work material SUS410
Number of revolutions (min) 2865
Cutting speed (m / min) 9.0
Feed rate (m / min) 716.3
Pilot hole diameter 0.89
Holder Collet chuck holder.
From this measurement diagram, the angle of intersection is narrower than the normal thread angle (60 degrees), and the inclination angle of the thread slope is increased. This is because the cutting speed is higher than the machining conditions shown in FIG. 5, and an unexpected load is applied in the axial direction during machining, resulting in over-rolling. Compared to FIG. 5, there is a noticeable peeling on the entrance side of the thread slope.
[0035]
FIG. 7 is a measurement diagram of a thread cut surface using a tap holder provided with the micro-slide mechanism of the present invention. The processing conditions at this time are
Tap name Rolling tap M1 × 0.25
Work material SUS410
Number of revolutions (min) 2865
Cutting speed (m / min) 9.0
Feed rate (m / min) 716.3
Pilot hole diameter 0.89
Holder Collet chuck holder.
[0036]
From this measurement diagram, the angle of intersection is close to the normal thread angle (60 degrees), and the thread is close to a normal rolled thread shape, and no peeling or overcoiling is observed. Since the results are obtained at high cutting speed and feed speed under the same processing conditions as the measurement data of FIG. 6, the effect of the tap holder provided with the micro slide mechanism of the present invention is recognized.
[0037]
【The invention's effect】
According to the present invention, when an unexpected axial load is applied to a tap being processed, the tap holder body slides in a direction that matches the tap pitch to prevent over-rolling of the thread. Can do. In particular, in tapping with small diameters (M2 or less) for difficult-to-cut materials, even under high-speed rotation and high cutting force processing conditions, processing defects such as excessive thread bulging and thread slope peeling due to over-rolling. Can be eliminated.
In addition, breakage of brittle and expensive small-diameter rolled taps due to momentary loads can be prevented, and a tip-shaped tap holder suitable for small-diameter tap sizes can be used, so that it can be used as a workpiece. The size can be adapted to the conventional tool interference problem.
[Brief description of the drawings]
[0038]
FIG. 1 is a cross-sectional view of an embodiment of a tap holder provided with an axial micro-slide mechanism of the present invention.
2 is an enlarged partial cross-sectional view of a main part of FIG.
FIG. 3 is a cross-sectional view showing a conventional tap holder.
FIG. 4A is an enlarged cross-sectional view of a screw thread when a small-diameter tap is processed with a conventional roll tap holder, and FIG. 4B is a cross-sectional view showing a normal roll screw thread shape.
FIG. 5 is a cross-sectional measurement diagram of a thread in which an over rolling failure has occurred.
FIG. 6 is a cut surface measurement diagram of a thread in which an over-rolling failure has occurred under different processing conditions.
FIG. 7 is a measurement diagram of a thread cut surface using a tap holder provided with a micro-slide mechanism of the present invention.
[Explanation of symbols]
[0039]
1 Shank 2 Small diameter rolling tap (Rolling tap)
3 Tap holder body 4 First spring 5 Second spring 8 Cover 9 Elastic body 10 Tightening nut 11 Collet chuck 12 Ball 14 Ring 15 Collar 16, 17 Set screw 18 Washer 20 Guide hole 21 Recess 23 Space 24 Small clearance 25 Spring receiving member 26 Shaft member 27 Holding portion 30 Main shaft

Claims (3)

A shank that is detachably mounted on a spindle of a machine tool having a tap synchronous feed mechanism;
A collet chuck that holds a rolling tap is detachably attached to the tip, and a tap holder body that is slidably inserted axially into the shank;
A first spring and a second spring disposed between the shank and the tap holder main body, biasing the tap holder main body in opposite directions in the axial direction, and stopping the tap holder main body at a position where the biasing force is balanced. The spring of
With
A shaft member extending in the axial direction is attached to the tap holder body, and a spring receiving member extending in the axial direction is provided in the shank so as to be movable in the axial direction, and the second spring is interposed via the spring receiving member. The tap holder body is urged in the direction of the rolling tap, and the first spring is supported by the spring receiving member, and the tap holder body is moved in the direction opposite to the rolling tap via the shaft member. Energized,
When a spindle feed error occurs during tapping and the feed amount and the tap pitch do not match, the tap holder body responds to an external force from a rolling tap attached to the tip to match the tap pitch. Tap holder with an axial micro-sliding mechanism characterized by micro-sliding in the direction. Between the shank and the tap holder body, thereby guiding the sliding in the axial direction of the tap holder body, that the engaging member for transmitting rotation of the shank in the tap holder body is provided with The tap holder provided with the axial direction micro slide mechanism of Claim 1 characterized by the above-mentioned. The engaging member is
A guide slot formed in the shank so as to extend in the axial direction,
A recess formed in the tap holder body at a position opposing to the elongated guide hole,
A ball engaging the tap holder body and the shank retaining state the elongated guide holes spanning the recess,
The tap holder provided with the axial direction micro slide mechanism of Claim 2 characterized by the above-mentioned.

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