JP2016203340A - Machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining method by which specific positions of screw mountain parts based on a reference position of a holder, which become start positions of tap cutting, can be identified easily with high accuracy, so that a work-piece can be subjected to female screw machining in a desirable shape using a machining machine.SOLUTION: A female screw machining method, which involves a holder 3 to be attached to a machining machine 41 and a tap 5 with screw mountain parts 23 to be assembled to the holder and is performed by identifying specific positions of the screw mountain parts of the tap based on a reference position 17 of the holder, comprises: a step of fitting a marking member 35 to a valley part 23d between tops of the screw mountain parts which overlap on an extension line 31 having the reference position of the holder extended in a shaft direction of the shave and exist next to each other, and aligning an arbitrary point of the marking member onto a virtual straight line S which is orthogonal to the shaft direction of the tap and passes through a bottom part of the valley part; a step of determining the arbitrary point of the marking member; a step of identifying positions of the screw mountain parts by increasing/decreasing half values of pitch P of the screw mountain parts; and a step of adjusting a start position of tap cutting by inputting the found-out positions of the screw mountain parts to the machining machine.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a machining method for performing female thread machining on a workpiece with a tap.

For example, a cylinder head (work) of an engine (mounted on an automobile) has a plug hole for mounting a spark plug. The plug hole female thread is processed using a tap tool.
Many tap tools have a holder that can be attached to a processing machine such as a machining center processing machine, and a tap that is implanted at the tip of the holder, and the holder is fixed to the tool attachment part of the processing machine. Then, by rotating the holder (including the tap) with a processing machine and sending the tip of the tap to the pilot hole in the plug hole, the female thread is processed in the pilot hole at the helical thread on the outer periphery of the tap. A plug hole is formed.

The direction of the side electrode (grounding electrode) arranged around the center electrode of the spark plug is used for the plug hole in order to eliminate combustion variation between engine cylinders, improve ignitability, and improve engine combustion efficiency. Is required to be in a specific orientation.
For this purpose, the plug hole needs to be accurately processed at a predetermined phase.
Also, in such a tap tool, the phase of the tap is adjusted and the specific position of the thread portion that is the reference for the predetermined phase is determined before the plug hole is threaded. There are some cases (all are preset). For example, in Patent Document 1, the position in the rotation direction of the tap is determined using a rotation direction positioning jig that positions the rake face of the thread portion of the tap, and the tap length is adjusted using a projector. In Patent Document 2, a cap to be screwed into a thread portion of a tap is prepared, and markings are respectively provided at predetermined positions of the cap and the holder. Then, the cap is put on the screw thread portion and tightened by screwing. After that, by loosening the cap until the respective markings coincide with each other, a specific position of the thread portion with respect to the holder is determined, and a holder having an adjustment mechanism for adjusting the axial length with the tap is used. By adjusting the tap length.

JP2012-240179A JP 2013-252594 A

However, the preset according to the former (Patent Document 1) requires a very complicated operation because the orientation of the tap tool is adjusted using a jig for positioning the rake face of the thread portion of the tap.
The preset by the latter (Patent Document 2) also requires a fitting allowance (gap) in order to screw the cap into the tap, and the length of the tap in the axial direction varies accordingly, with high accuracy, There is a possibility that the position of the specific thread part cannot be determined.

  Accordingly, an object of the present invention is to determine the position of a specific thread portion with reference to the reference position of the holder, which is a tap cutting start position, with a simple and high accuracy, and a workpiece having a desired shape on the workpiece. A machining method capable of performing female thread machining is provided.

  An aspect of the present invention includes a holder that can be attached to a processing machine, and a tap that is assembled to the holder and has a spiral thread portion on an outer peripheral portion, and the screw thread portion of the tap with respect to the reference position of the holder. A processing method for determining a specific position and subjecting a workpiece to internal thread processing, the top portions of a pair of screw thread portions that are adjacent to each other and overlap on an extension line extending the reference position of the holder along the axial direction of the tap A first step of fitting a marking member into a trough between the two and aligning any point of the marking member on a virtual straight line that is orthogonal to the axial direction of the tap and passes through the bottom of the trough, and marking fitted in the trough The second step of grasping the position of an arbitrary point of the member and the position of either one of the pair of thread portions are determined by adjusting the half value of the pitch of the thread portion to the position of the arbitrary point of the marking member. Third And extent, and as having a fourth step of either of the positions of the pair of screw crest indexing in the third step to enter the machine to adjust the cutting start position of the tap.

  According to the present invention, using the concept of an extension line that extends the reference position of the holder along the axial direction of the tap, it is overlapped on the extension line and between the tops of a pair of thread portions that are adjacent to each other. Marking the thread part to be indexed by fitting the marking member into the valley, and identifying the position of the thread part specified based on the position of any point on the marking member The position of a specific thread portion can be determined with high accuracy. As a result, by inputting the determined position of the specific thread portion into the processing machine and adjusting the tap cutting start position as appropriate, it is possible to perform processing in an appropriate state and easily process the desired shape on the workpiece. Can be applied.

The perspective view which shows the whole tap tool used for the processing method of the 1st Embodiment of this invention with the state in which the spherical marking member was fitted. The exploded perspective view of a tap tool. (A) is the arrow view seen from the arrow A in FIG. 1 which shows the position of the spherical marking member fitted to the thread part, (b) is the perspective view explaining when fitting the marking member to the thread part. Figure. The side view seen from the arrow B in FIG. The arrow view seen from the arrow C in FIG. 4 explaining the index position of the specific screw thread part from the center position and the same center position of a marking member with the image of a projector. The side view explaining when a tap position is correct | amended by the processing machine side according to the position of the specified specific thread part. The side view explaining when calculating the cutting start position of a tap using the marking member of a different shape used as the principal part of the 2nd Embodiment of this invention.

The present invention will be described below based on the first embodiment shown in FIGS.
FIG. 1 shows a tap tool 1 used for subjecting a pilot hole for mounting a spark plug disposed in a cylinder head (work) of an automobile (vehicle) engine, for example.
As shown in FIGS. 1 and 2, the tap tool 1 includes a holder 3 and a tap 5. Among these, the holder 3 includes, for example, an inverted frustoconical base 7, a flange portion 9, a short columnar base portion 11, a cylindrical tap receiving portion 13, and a disk-shaped tap fixing tool 15 (for example, advancing and retreating). It is formed by connecting together those that are fixed by displacement (axial direction). A cutout portion 17 that is positioned with the processing machine is provided in a part of the outer peripheral portion of the base 7.

  As shown in FIGS. 1 (a), 1 (b) and 2, the tap 5 has, for example, an elongated hook-like portion 21 and a spiral formed on the outer periphery of the distal end of the hook-like portion 21, for example, 1.5 mm. And a screw thread portion 23 that draws a spiral at the pitch P. For example, the screw thread portion 23 is composed of a screw thread piece 23 a that is divided into four in a substantially cross shape around the axis of the flange-shaped portion 21. The screw thread portion 23 includes an incomplete screw portion 24a forming the biting portion V1 in the V1 range on the distal end surface side, and a complete screw portion 24b formed in the V2 range following the proximal end side of the incomplete screw portion 24a. (See FIG. 1 and FIG. 4).

The proximal end side (the side opposite to the threaded portion 23) of the hook-like portion 21 is inserted into a tap insertion hole 25 formed in the center portion of the tap fixture 15 and the tap receiving portion 13. And the hook-shaped part 21 and the holder 3 are fixed with the tap fixing tool 15, and the thread part 23 is arrange | positioned in the position protruded from the holder 3 (refer FIG. 1).
As shown in FIG. 6, the tap portion 5 of the tap tool 1 is a tool mounting portion of a processing machine 41 constituted by, for example, a machining center processing machine. By being attached to 43 in a predetermined posture, the internal thread is processed in the lower hole 27 of the plug hole of the cylinder head 26 (work) by the rotation of the tap 5 and the feed of the tap 5 by the processing machine 41.

Here, since the processing machine 41 performs threading by numerical control, for example, when a correction value is input to the input panel 47 connected to the control unit 45 as shown in FIG. 6, the tap 5 is set to a predetermined value based on the correction value. The phase is adjusted. That is, the processing machine 41 adjusts the direction of the tap 5 in the rotational direction and the axial position of the tap 5 so that the tap 5 has a predetermined phase.
At this time, since the main shaft portion 43 of the processing machine 41 is integrated with the holder 3 and the holder 3 is integrated with the tap 5, the specific position of the helical thread portion 23 with respect to the reference position of the holder 3 is determined. Thus, it can be seen that the cutting start position of the tap 5 is adjusted to be constant. That is, when the tap tool 1 is attached to the processing machine 41, that is, when the tap tool 1 is a single product, the specific position of the thread portion 23 based on the reference position of the holder 3 is determined ( (Preset), by inputting the determined position to the processing machine 41, the predetermined phase, that is, the cutting start position of the tap 5 is adjusted by numerical control.

Therefore, a method is used in which the specific position of the thread portion 23 is determined from the single tap tool 1 with reference to the reference position of the holder 3 (preset).
The presetting of the tap tool 1 will be described. In this embodiment, as shown in FIGS. 1A, 1B, 3 and 4, hard balls 35 having a diameter of 1 mm, for example, as spherical marking members are mutually connected. It starts from fitting into a trough between the tops of a pair of adjacent thread pieces 23a (thread parts 23).

  Here, as shown in FIG. 4 and FIG. 5, the hard ball 35 is not the incomplete thread portion 24a in the V1 range in which the mountain shape is ambiguous, but is the complete thread portion 24b in the V2 range, which is also out of the complete thread portion 24b. The first crest 23b located at the tip of the first crest 23b and the second crest 23b adjacent to the base end of the first crest 23b is fitted into a valley 23c (first step of the present application). Incidentally, the hard ball 35 is fixed to the tap 5 by using, for example, a steel ball (FIG. 3B) having a string-like member 36 inserted in the center and binding the periphery of the screw thread portion 23 with the string-like member 36. It is supposed to be. Incidentally, the marking member is not limited to this, and may be made of resin or ceramic, for example. When the marking member is made of resin, the marking member is easily pressed and fixed to the valley portion by its elastic force.

  Subsequently, as shown in FIG. 2, the tap 5 is set in the holder 3 while matching the hard ball 35 fitted in the screw thread portion 23 with the reference position of the holder 3. When the hard ball 35 is fitted into the valley portion 23c, as shown in FIG. 5, an arbitrary point (this embodiment) of the hard ball 35 is placed on a virtual straight line S that is orthogonal to the axial direction of the tap 5 and passes through the bottom portion of the valley portion 23c. In the form, the center point) is aligned. In the present embodiment, for example, the center position of the notch 17 is used as the reference position of the holder 3.

  In order to clearly recognize this reference position, for example, an alignment base line 31 (here, for example, a thick line) extending along the axial direction of the tap 5 is provided on the end surface portion of the base portion 11 and the outer peripheral surface portion of the tap receiving portion 13. Straight line) is provided. Moreover, as a mark which suggests the center position of the circular-arc outer periphery in a certain one thread piece 23a on the outer peripheral surface of the collar-shaped part 21 among the taps 5 so that a certain range of the thread piece 23a may be recognized clearly. For example, a linear index 33 extending in the axial direction may be provided.

  The tap 5 is inserted from the tap insertion hole 25 to the bottom of the hole 25 while matching the index 33, that is, the hard ball 35 fitted in the screw thread portion 23 and the base line 31. Then, the base end portion of the tap 5 is fixed by the tap fixing tool 15. Thereby, the tap 5 is attached to the holder 3 in a posture in which the hard ball 35 fitted in the screw thread portion 23 and the reference position (the notch portion 17) of the holder 3 coincide with each other. This completes the first step.

Note that the tool length at this time, for example, the length T1 between the lower end of the flange portion 9 serving as the holder end surface and the tip of the tap 5 serving as the tool tip is defined as “100 mm”.
Next, the center position (height) of the hard ball 35 fitted in the valley 23c is grasped.
For example, using a projector (not shown), the tip of the tap 5 is projected from the direction of arrow C in FIG. 4, for example, and displayed on the screen of the projector as shown in FIG. 5, for example. Then, for example, using the cross-shaped indicators 37a and 37b projected on the screen and the indicators 37c and 37d newly provided on the screen as shown in FIG. And the tool length T2 from the same position to the lower end of the flange portion 9 which is the end face of the holder. This completes the second step. The tool length T2 at this time is, for example, “96 mm”. When the operation so far is completed, the hard ball 35 is removed from the tap 5.

  And the position of the specific thread part which exists on the base 31 and the extension line a of the parameter | index 33 is calculated on the basis of the center position of the hard sphere 35. FIG. That is, as shown in FIG. 5, since the center of the hard sphere 35 exists at the center of the pitch P (distance between the peak and the peak), the base line 31 and the hard sphere 35 on the extension line a of the index 33 The height of a specific adjacent thread portion, here, the apex height T3 (vertex position) of the thread portion 23d immediately above the hard ball 35 is, for example, the pitch P of the thread portion 23 is “1.5 mm”. The value obtained by adding half the value α (half value) of the pitch P to the center height of the hard sphere 35 is obtained. Specifically, the apex height T3 in the screw thread portion 23d is obtained based on the pitch P such that “96 mm (T2) +0.75 mm (α) = 96.75 mm”. As a result, the position of the specific thread portion 23d of the tap 5 with respect to the reference position of the holder 3 is determined. This completes the third step. Note that the apex height of the thread portion 23e immediately below the hard ball 35 may be obtained. In this case, the apex height of the thread portion 23e is obtained by subtracting the half value α (half value) of the pitch P from the above-described value T2.

Next, a method for setting a tap position when a female thread is machined into the lower hole 27 (plug hole) of the cylinder head 26 using the tap tool 1 will be described.
The tap tool 1 is mounted on the main shaft portion 43 of the processing machine 41. Thereby, the tap tool 1 is assembled | attached to the main axis | shaft part 43 with a fixed attitude | position (direction) according to the fitting of the notch part 17 and a main axis | shaft part.

  Then, by inputting, for example, a difference in height (3.25 mm) of a specific thread portion 23d with respect to a predetermined amount of tool length T1 from the input panel 47 of the processing machine 41 as a correction amount, the spindle is based on this correction amount. The position of the tap tool 1 is displaced by numerical control (rotation, feed, etc. of the main shaft part 43) through the part 43, and correction for 3.25 mm is performed. Thereby, the cutting start position of the tap tip is set to a predetermined location. That is, for example, by bringing the position of the tap tool 1 close to the work by 3.25 mm, the cutting start position of the tap tip is set at a predetermined position, and the distance between the tap 5 and the cylinder head 26 that is the work is defined as a specified dimension. Adjust to. This completes the fourth step.

With such a setting, a female screw process is applied to the pilot hole 27 of the plug hole of the cylinder head 26 to match the predetermined direction of the spark plug.
Further, the cutting start position of the tap 5 may be changed according to the situation of the processing machine 41 when the tap 5 is mounted.
For example, when the tap 5 has a predetermined amount of tool length, as shown in FIG. 6A, the distance M between the seating surface of the lower hole 27 of the cylinder head 26 and the cutting start position of the tap tip is predetermined. And

  At this time, when the position of the tap tip is approached to the seating surface of the lower hole 27, it is required to avoid interference between the seating surface of the lower hole 27 and the tap end. In this case, as indicated by a two-dot chain line in FIG. 4, the position of the specific thread portion 23d previously determined is changed to the front side (the tip direction or the direction approaching the workpiece). That is, an integral multiple (n × P) of the pitch P of the thread portion 23 is added to the value of the position (T3) of this specific thread portion 23d, and the tool length T1 (end surface position) of the tap 5 is exceeded. The specific position of the virtual thread portion 23d at the time is obtained (T4). For example, this time, as 101.25 mm (96.75 mm + (1.5 mm × 3)), the pitch P is changed from T3 to T4. Thereby, as shown in FIG. 6B, the tip of the tap is disposed at a position retracted by 1.25 mm from the case of a predetermined amount of tool length. That is, the processing is performed appropriately without the tap tip interfering with the cylinder head 26 (work).

If the position of the tap tip falls within an allowable range, for example, the position of the specific thread portion 23d determined based on the center position of the hard ball 35 as shown in FIG. 6A is used.
On the other hand, when the position of the tip of the tap is excessively separated from the seat surface of the lower hole 27, for example, the position of the specific thread portion 23d is moved rearward (base end direction or away from the workpiece) to the thread portion 23. Change to the position where the pitch P is reduced. As a result, the correction amount becomes larger than the above-described “3.25 mm”, the position of the tap tool 1 is further brought closer to the work, the cutting start position of the tap tip is set at a predetermined position, and the tap and the work are formed. The distance is adjusted to a specified dimension (see FIG. 6C).

  In summary, the hard ball 35 is fitted between the tops of the thread portions 23, the thread portion 23d to be indexed is specified, and then the specific position is determined based on the center position of the hard ball 35 (marking member). Thus, the specific thread portion 23d (the height of the specific thread portion 23) based on the reference position (notch portion 17) of the holder 3, which is the reference (position) for starting the cutting of the tap 5, is highly accurate. Can be determined by Then, by inputting the height of the specific thread portion 23d determined here to the processing machine 41 and adjusting the cutting start position of the tap 5 as appropriate, processing in an appropriate state is possible, and the workpiece has a desired shape. Female thread is processed. Thereby, the workpiece processed into the desired shape can be easily obtained. In particular, by using a hard ball 35 (spherical) as a marking member, it is easy to fit in the valley 23c of the thread portion 23 and is easily fixed to the valley 23c, so that workability is good. Further, in the step of grasping the position of the marking member (second step), if the grasped position is the center position, the position can be easily identified, and the step of grasping the position of the marking member can be performed smoothly.

In addition, since the hard sphere 35 is positioned using a projector, the thread portion 23d can be accurately indexed.
Further, the determined position T3 of the specific thread portion 23d is increased or decreased by an integral multiple of the pitch P of the thread portion 23, so that the tap 5 of the tap 5 is attached to the processing machine 41 depending on the situation. The cutting start position can be adjusted appropriately.

In addition, the hard ball 35 is fitted into the valley portion 23c between the first crest located at the tip of the complete screw portion 24b and the second crest adjacent to the base end side of the first crest, so that a stable index is always obtained. It is easy to set the cutting start position of the tap 5 appropriately.
FIG. 7 shows a second embodiment of the present invention.
In the present embodiment, the marking member is not spherical like a hard sphere, but is a single member having a triangular cross section that can be fitted into the valley 23c between the first and second crests of the complete screw portion 24b, that is, the trough 23c. The cross-sectional triangular member 55 along the shape is used. Even if it does in this way, there exists an effect similar to 1st Embodiment. Of course, the marking member is not spherical or triangular in cross section, and may have other shapes.

However, in FIG. 7, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In addition, each structure, combination, etc. in embodiment mentioned above are examples, and it cannot be overemphasized that addition of a structure, omission, substitution, and other changes are possible within the range which does not deviate from the meaning of the present invention. Absent. Further, the present invention is not limited to the above-described embodiment, and needless to say, is limited only by the “claims”. For example, in the first embodiment, the height of the specific thread portion 23d is determined based on the center position of the spherical marking member. However, the reference position may not be the center position of the marking member. That is, an arbitrary point located on the virtual straight line S of the first embodiment among the marking members may be used as a reference. Also, for example, when the marking member as in the second embodiment shown in FIG. 7 has a triangular cross section, that is, the triangular triangular member 55 has a specific thread on the basis of the point K as shown in FIG. The height of the portion 23d may be determined.

1 Tap tool 3 Holder 5 Tap 17 Notch (reference position of holder)
23 Thread part 23a Thread piece 23b Top part 23c Valley part 23d Specific thread part 24a Incomplete thread part 24b Complete thread part 26 Cylinder head (workpiece)
35, 55 Hard sphere, triangular section member (marking member)
41 Processing machine P Pitch S Virtual straight line

Claims (4)

A holder that can be attached to the processing machine, and a tap that is assembled to the holder and has a spiral thread portion on the outer periphery, and a specific position of the thread portion of the tap with respect to the reference position of the holder A processing method for indexing and subjecting a workpiece to internal thread processing,
A marking member is fitted into a trough between the tops of a pair of threaded portions that are adjacent to each other and extend on an extension line extending the reference position of the holder along the axial direction of the tap, and the axial direction of the tap A first step of aligning an arbitrary point of the marking member on an imaginary straight line that is orthogonal to the valley and passes through the bottom of the valley,
A second step of grasping the position of the arbitrary point of the marking member fitted in the valley,
A third step of determining the position of one of the pair of screw threads by adding or subtracting half the pitch of the screw threads to the position of the arbitrary point of the marking member;
A fourth step of inputting the position of any one of the pair of screw threads determined in the third step to the processing machine and adjusting a cutting start position of the tap;
A processing method characterized by comprising:   The processing method according to claim 1, wherein the marking member is spherical, and the arbitrary point is a center of the marking member.   One of the pair of thread portions that have been determined in the third step is defined as a specific thread portion, and the position of the specific thread portion is increased or decreased by an integral multiple of the pitch of the thread portion. The processing method according to claim 1, wherein the starting position of cutting the tap is adjusted. The thread portion of the tap has an incomplete mountain portion on the distal end side and a complete mountain portion continuing to the proximal end side of the incomplete mountain portion,
In the first step, the marking member is fitted into a trough between a first crest located at the tip of the complete crest and a second crest adjacent to the base end side of the first crest. The processing method according to any one of claims 1 to 3.

Images