JP2004154885A - Hole machining tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hole machining tool which eliminates such a bother as to measure an inner diameter of a circular hole 7 formed in a workpiece 6 whenever the hole is formed, to thereby reduce costs required for finishing the circular hole. <P>SOLUTION: The workpiece 6 has a prepared hole formed therein beforehand, and an inner peripheral surface thereof is ground by a grindstone 2 to form the circular hole 7 having the predetermined inner diameter. Then a rod portion 3 supporting the grinding bar 2 is sheathed with a radial needle bearing 4 in an axially movable manner, and the radial needle bearing 4 is pressed to the grinding bar 2 via a sleeve 13. The outer diameter of an outer ring 12 of the radial needle bearing 4 is set to a lower limit value of an allowable dimension of the circular hole 7. When the grindstone 2 is worn and the inner diameter of the circular hole 7 becomes smaller, the outer ring 12 cannot enter the interior of the circular hole 7, and therefore a displacement sensor 5 detects the fact, which notifies the operator that the hole machining tool 1 should be exchanged. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a so-called one-pass machining tool, which is a so-called one-pass machining tool, which finishes an inner diameter of a pilot hole formed in a workpiece in advance to a desired inner diameter. In particular, the present invention realizes a structure capable of confirming whether or not the inside diameter of the prepared hole has been finished to a desired value simultaneously with finishing the inside diameter of the prepared hole.
[0002]
[Prior art]
When forming a circular hole having a desired inner diameter in a metal material constituting various types of mechanical devices, first, a pilot hole having an inner diameter slightly smaller than the inner diameter is formed by a drilling machine or the like. After that, a drilling tool called a one-pass drilling tool is inserted into the pilot hole only once while rotating and pulled out by a drilling device. By this operation, the inner diameter of the pilot hole is expanded to a desired value, which is the rotation diameter of the processing part of the drilling tool.
[0003]
The machined portion of the hole machining tool gradually wears due to repetition of the machining operation, and the rotation diameter also gradually decreases. Finally, the inner diameter of the circular hole after processing deviates in a direction smaller than the allowable range for the desired value, that is, the value obtained by subtracting the tolerance from the reference value. In this way, when the inner diameter of the circular hole after processing by the hole drilling tool is out of the allowable range, the worn tool for hole drilling is removed from the rotating shaft of the hole drilling apparatus, and a new hole drilling tool is removed. A tool must be mounted on this axis of rotation.
[0004]
Conventionally, for this purpose, a workpiece having a circular hole that has been subjected to finish processing by a hole drilling tool is transferred from a processing station to a measuring station, and then the circular workpiece is measured by a measuring instrument such as a pin gauge or an air micro gauge. The inner diameter of the hole was being measured. Then, based on the measured value, it is determined whether or not the inner diameter is within an allowable range, and the workpiece is sorted into a good product and a defective product. As for the defective product, since the inner diameter of the circular hole is shifted to the smaller diameter side than the allowable range of the desired value, rework is performed using the new hole drilling tool.
[0005]
[Problems to be solved by the invention]
As described above, in the case of the conventional technique for processing a circular hole having a desired inner diameter, the finishing of the circular hole and the measurement of the inner diameter are performed at separate stations (two types of stations are required). In addition to increasing the equipment cost for drilling, the processing time is prolonged and the processing cost is increased.
The drilling tool of the present invention has been invented in view of such circumstances.
[0006]
[Means for Solving the Problems]
A hole drilling tool according to the present invention includes a drilling unit, a holding unit, a slide member, and a detecting unit.
Of these, the processing portion, the outer peripheral surface is configured with a whetstone, or a cutting blade, by cutting the inner peripheral surface of the circular hole with the rotation, the inner diameter of this circular hole, the rotation diameter matches Process to the desired value.
The holding portion is provided rearward of the processed portion and concentrically with the processed portion in the direction of insertion into the circular hole.
Further, the slide member is supported by the holding portion so as to freely move in the axial direction while preventing movement in the radial direction.
Further, the detecting means is for detecting an axial displacement of the slide member.
The outer diameter of the slide member is the lower limit of the allowable range of the inner diameter of the circular hole.
[0007]
[Action]
According to the drilling tool of the present invention configured as described above, it is possible to confirm whether or not the inner diameter of the circular hole obtained by the finishing is finished to a desired value, simultaneously with the finishing of the inner diameter of the pilot hole. . In other words, if the processed portion does not wear, or even if it is worn, when the amount of wear is limited, the inner diameter of the circular hole is set within the allowable range, that is, the reference value related to the desired value. Within the tolerance range. In this state, since the inner diameter of the circular hole is equal to or larger than the outer diameter of the slide member, the slide member enters the circular hole together with the holding portion (without sliding with respect to the holding portion).
[0008]
On the other hand, as the wear of the processed portion progresses, the inner diameter of the circular hole deviates from the allowable range, and if the inner diameter becomes too small, even when the holding portion enters the circular hole, The slide member cannot enter this circular hole. As a result, regardless of the displacement of the holding section, the slide member remains at the original position. Therefore, if the state where the slide member stays at the original position is detected by the detecting means irrespective of the displacement of the holding portion, the abrasion of the processing portion progresses, and the inner diameter of the circular hole deviates from the allowable range. I understand.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example of an embodiment of the present invention. The drilling tool 1 of this example includes a grindstone 2 serving as a processing unit, a rod unit 3 serving as a holding unit, a radial needle bearing 4 serving as a slide member, and a displacement sensor 5 serving as detecting means. Such a drilling tool 1 finishes the inner peripheral surface of a pilot hole (circular hole) previously drilled in the workpiece 6 and forms the pilot hole into a circle having a desired inner diameter. It is used for finishing to form the hole 7.
[0010]
Of these, the grindstone 2 has an outer peripheral surface formed in a columnar shape, and the inner diameter of the prepared hole is scraped off with the rotation to reduce the inner diameter of the prepared hole to a desired value corresponding to the rotation diameter. It is expanded to form the circular hole 7. Such a grindstone 2 is provided between a tapered tapered guide portion 8 and a cylindrical guide portion 9 so as to be concentric with the guide portions 8 and 9. The outer diameters of these two guide portions 8 and 9 (the maximum outer diameter of the tapered guide portion 8) are smaller than the rotation diameter of the grinding wheel 2.
[0011]
The rod portion 3 is provided concentrically with the grinding wheel 2 behind (upper in FIG. 1) the grinding wheel 2 with respect to the insertion direction into the circular hole 7 (the pilot hole). In the case of, it has a rod shape.
Further, the radial needle bearing 4 has a cylindrical outer ring 12 around the rod portion 3, which is concentric with the rod portion 3 by a plurality of needles 11, 11 which are rotatably held by a retainer 10. And, it is supported so that it can rotate around the rod portion 3 freely. The retainer is formed at both ends in the axial direction (vertical direction in FIG. 1) of the outer ring 12 by, for example, bending a metal plate constituting the outer ring 12 inward in the radial direction to form a locking flange. 10 and a means for preventing the needles 11 and 11 from coming off are provided. Accordingly, the retainer 10 and the needles 11 and 11 are displaced in the axial direction of the rod 3 together with the outer ring 12.
[0012]
Such a radial needle bearing 4 is in a state in which a slight preload is applied to the needles 11 between the outer peripheral surface of the rod portion 3 and the inner peripheral surface of the outer ring 12. In other words, the internal clearance of the radial needle bearing 4 is made negative. Therefore, the outer ring 12 is rotatably supported around the rod portion 3, concentrically with the rod portion 3, and in a state where displacement in the radial direction is prevented. The outer diameter of the outer ring 12 is a lower limit value of the allowable range of the inner diameter of the circular hole 7, that is, a value (R-ΔR) obtained by subtracting the tolerance ΔR from the reference value R of the inner diameter.
[0013]
A sleeve 13 is fitted around the rod portion 3 on the opposite side of the radial needle bearing 4 from the guide portion 9 so as to be axially movable with respect to the rod portion 3. The sleeve 13 has an outwardly flanged flange 15 formed at one end (upper end in FIG. 1) of the cylindrical portion 14, and the cylindrical portion 14 is slidably attached to the rod 3. It is fitting. A biasing spring 17 such as a compression coil spring is provided between the sleeve 16 and the stopper 16 supported and fixed by a pin or the like at a portion of the rod portion 3 near the front end (upward in FIG. 1). The radial needle bearing 4 is elastically pressed toward the grindstone 2 (downward in FIG. 1) via the sleeve 13.
[0014]
Further, the displacement sensor 5 is supported by a portion of the sleeve 13 that can be in close proximity to the outer peripheral edge of the flange 15 on the side of the rod 3. As the displacement sensor 5, a sensor such as a capacitance-type non-contact sensor that can detect whether or not the flange portion 15 is present in the vicinity of the detection portion and, if so, the position thereof is used.
[0015]
According to the drilling tool of the present invention configured as described above, simultaneously with the finishing of the inner diameter of the pilot hole, it is checked whether the inner diameter of the circular hole 7 obtained by the finishing is within the allowable range. Can be performed. In other words, when the grinding wheel 2 is not worn, or even when worn, the amount of wear is limited, the inner diameter of the circular hole 7 is set to a tolerance ± △ R centered on the reference value R. It falls within the range (R ± ΔR). In this state, the inner diameter of the circular hole 7 is equal to or larger than the outer diameter (R- △ R) of the radial needle bearing 4. Therefore, while the radial needle bearing 4 is pressed against one end surface (the upper end surface in FIG. 1) of the guide portion 9 by the urging spring 17, the radial needle bearing 4 slides upward with respect to the rod portion 3. (Without doing so).
[0016]
In this case, the flange 15 is lowered to a position shown by a solid line in FIG. As a result, the displacement sensor 5 detects the lowering of the flange portion 15, and a controller (not shown) receiving the signal from the displacement sensor 5 sets the inner diameter of the circular hole 7 to the lower limit value (R- △ R ) It is judged that it is above. Therefore, in this case, the controller continues the machining operation without issuing a warning or the like for prompting the replacement of the drilling tool 1. In this case, the radial needle bearing 4 enters the circular hole 7, and the outer peripheral surface of the outer ring 12 constituting the radial needle bearing 4 comes into contact with the inner peripheral surface of the circular hole 7. However, in this case, the two peripheral surfaces are prevented from rubbing each other based on the rolling of the needles 11 and 11. Therefore, the inner peripheral surface of the circular hole 7 that has just been finished is not damaged.
[0017]
On the other hand, the abrasion of the grinding wheel 2 proceeds, and the inner diameter of the circular hole 7 is out of the allowable range for the desired value {below a lower limit (R-ΔR) obtained by subtracting a tolerance from a reference value}. . If the inner diameter becomes too small in this way, the radial needle bearing 4 cannot enter the circular hole 7 even if the rod portion 3 enters the circular hole 7. As a result, regardless of the displacement of the rod portion 3, the radial needle bearing 4 remains at the original position. Then, the position of the flange portion 15 remains at a position away from the one end opening of the circular hole 7 as shown by a chain line in FIG. Therefore, when the displacement sensor 5 detects that the position of the flange portion 15 remains at a position away from the one-end opening, the controller causes the wear of the grinding wheel 2 to proceed and the circular hole to move. It is determined that the inner diameter of 7 is out of the allowable range. Then, the controller issues a warning or the like for prompting replacement of the drilling tool 1 and stops the drilling operation.
[0018]
Even if the grinding wheel 2 wears and the inner diameter of the circular hole 7 is out of the range of the tolerance with respect to the desired value, the radial needle bearing 4 cannot suddenly enter the circular hole 7 at all. That is, the amount of wear of the grindstone 2 for each hole drilling is a small dimension of less than 1 μm in diameter. In addition, the metal workpiece 6 expands slightly due to a rise in temperature when it is lowered, and also elastically deforms, albeit slightly. Therefore, the radial needle bearing 4 cannot enter the circular hole 7 little by little with the progress of the wear of the grinding wheel 2. In other words, the axial length that can enter the circular hole 7 decreases slightly. Therefore, a threshold value is provided in the determination circuit of the controller, and when the penetration length of the radial needle bearing 4 into the circular hole 7 becomes equal to or less than the threshold value, the controller prompts the replacement of the hole machining tool 1. A warning is issued and the machining operation is stopped.
[0019]
The above description has been made on the premise that the inner diameter of the circular hole 7 is finished by the grindstone 2 and when the grindstone 2 is worn, the drilling tool 1 is replaced. On the other hand, when the present invention is applied to a hole drilling tool whose working diameter can be adjusted from the outside, the above working diameter is increased when the inner diameter of the circular hole becomes smaller than the lower limit of the allowable range. You can also. Two examples of a drilling tool that can be used in such a case will be described with reference to FIGS.
[0020]
The drilling tool 1a of the first example shown in FIGS. 2 and 3 is related to Japanese Patent Application No. 2002-61601, and includes a holder 18, a pivot 19, a swing arm 20, and a cutting blade. 21, an urging spring 22 such as a disc spring, a pressing piece 23, and an adjustment nut 24. The drilling tool 1a provided with such members 18 to 24 rotates around the central axis of the holder 18 during use, that is, during drilling work.
[0021]
The holder 18 is formed in a cylindrical shape as a whole, and has a center hole 25 penetrating in the axial direction. Further, the pivot 19 is provided at a tip portion (a lower end portion in FIG. 2) of the holder 18 so as to cross the center hole 25. Further, the swing arm 20 has its intermediate portion supported by the pivot 19 so as to be capable of swinging displacement, and has its first half (lower half in FIG. 2) projected outside the holder 18 and The base half (the upper half in FIG. 2) is located in the holder 18. The cutting blade 21 is held and fixed to the tip of the swing arm 20 so as to protrude from one side surface 26 of the swing arm 20 in the radial direction of the holder 18 (to the left in FIG. 2). ing.
[0022]
Further, the urging spring 22 and the pressing piece 23 extend in the axial direction of the holder 18 including the central axis of the pivot 19 in order to adjust the position of the cutting blade 21 in the radial direction of the holder 18. With respect to the virtual plane α, they are provided on opposite sides.
The cutting spring 21 projects from the inner side surface of the intermediate portion of the holder 18 and the other side surface 27 of the base end portion of the swing arm 20, that is, the radial direction of the swing arm 20. And the opposite side. Therefore, the urging spring 22 imparts elasticity to the swing arm 20 in a direction to reduce the rotation diameter of the cutting blade portion of the cutting blade 21.
[0023]
On the other hand, the pressing piece 23 is provided between the inner side surface of the intermediate portion of the holder 18 and the one side surface 28 of the base end portion of the swing arm 20, that is, the surface on the side from which the cutting blade 21 projects. The holder 18 is pushed so as to be freely displaceable in the axial direction. Then, as the pressing piece 23 is pushed between the inner side surface of the intermediate portion of the holder 18 and the one side surface 28 of the base end of the rocking arm 20, the rocking arm 20 moves clockwise in FIG. The cutting blade 21 oscillates so that the rotating diameter of the cutting blade portion of the cutting blade 21 increases. For this reason, in the case of the illustrated example, the base end portion one side surface 28 is slightly inclined with respect to the center axis of the swing arm 20 so that the inner side surface of the intermediate portion of the holder 18 and the swing arm 20 The distance between the base portion and the one side surface 28 is reduced toward the distal end of the holder 18.
[0024]
The adjusting nut 24 is screwed into a female screw portion 29 formed on the inner peripheral surface of the base half of the holder 18, and its distal end surface (lower end surface in FIG. 2) abuts against the proximal end surface of the pressing piece 23. ing. In the center of the base end surface (the upper end surface in FIG. 2) of the adjusting nut 24, an engaged portion 30 which is a non-circular concave hole such as a hexagonal hole is formed, and the adjusting nut 24 is attached to the holder. A rotatable shaft (not shown) inserted from the base end opening 18 allows rotation. Then, with the adjustment nut 24 displacing the pressing piece 23 to the tip end side (the lower side in FIG. 2) of the holder 18, the swing arm 20 resists the elastic force of the urging spring 22. Swing displacement is possible.
[0025]
When the present invention is applied to the above-described hole forming tool 1a according to the prior invention, the tip (lower half of FIG. 2) of the swing arm 20 is diametrically outward of the holder 18 (see FIG. 2). For example, by bending the cutting blade 21 to the left), the rotating diameter of the cutting blade 21 is made sufficiently larger than the outer diameter of the holder 18. The holder 18 is used as a holding unit according to the first aspect of the present invention, and around the holder 18, detection means including the slide member such as the radial needle bearing 4 shown in FIG. 1 and the displacement sensor 5 are provided.
[0026]
As described above, when the present invention is applied to the drilling tool 1a according to the above-described invention, when the inner diameter of the circular hole 7 (FIG. 1) is smaller than the lower limit of the allowable range, the adjusting nut is rotated by a rotating shaft (not shown). By rotating 24, the pressing piece 23 is displaced in the axial direction of the holder 18. Then, the swing arm 20 to which the cutting blade 21 is fixed is oscillated about the pivot 19 to enlarge the rotation diameter of the cutting blade portion of the cutting blade 21. Therefore, automation of hole processing becomes possible.
[0027]
Next, a drilling tool 1b shown in FIG. 4 is a processing tool called a reamer, which is described in Japanese Patent Application Laid-Open No. 2000-84733, and is capable of expanding and contracting the outer diameter of a processing portion. Such a drilling tool 1b shown in FIG. 4 has a substantially tubular main body 31 which is provided with a slit at the tip and which can be expanded and contracted, a tapered cone 32 fitted inside the tip, and a tapered cone 32. The pull rod 33 has a base end connected and fixed thereto, and a rotary sleeve 34 screwed to the base end of the pull rod 33. In the case of such a drilling tool 1b, if the tapered cone 32 is pulled into the main body 31 via the pull rod 33 by rotating the rotary sleeve 34, the outer diameter of the distal end of the main body 31 is reduced. As a result, the rotating diameter of the processed portion provided on the outer peripheral surface of the distal end portion increases.
[0028]
When the present invention is applied to the hole drilling tool 1b as described above, the outer diameter of the tip of the main body 31 is increased, or conversely, the outer diameter of the base half is reduced. The rotating diameter of the processing portion provided at the distal end of the main body 31 is made sufficiently larger than the outer diameter of the base half of the main body 31. The base half of the main body 31 serves as a holding portion according to claim 1, and a detecting means including a slide member such as the radial needle bearing 4 shown in FIG. Is provided.
[0029]
As described above, when the present invention is applied to the hole drilling tool 1b, when the inner diameter of the circular hole 7 (FIG. 1) falls below the lower limit of the allowable range, the rotary sleeve 34 is rotated by a rotary shaft (not shown). Then, the tapered cone 32 is pulled into the main body 31. Then, the rotation diameter of the processing portion provided on the outer peripheral surface of the distal end portion of the main body 31 is enlarged. Therefore, automation of hole processing becomes possible.
[0030]
【The invention's effect】
Since the present invention is configured and operates as described above, it is not necessary to measure the inner diameter of a circular hole whose inner peripheral surface has been subjected to finishing processing by a hole drilling tool each time, and it is not necessary to measure a circular hole having a desired inner diameter. The cost required for finishing can be reduced.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of a hole drilling tool according to the present invention.
FIG. 2 is a cross-sectional view showing a first example of a hole drilling tool to which the present invention can be applied and whose processing diameter can be adjusted from the outside.
FIG. 3 is a sectional view taken along line AA of FIG. 2;
FIG. 4 is a cross-sectional view showing a second example of a hole drilling tool to which the present invention can be applied and whose processing diameter can be adjusted from the outside.
[Explanation of symbols]
1, 1a, 1b Drilling Tool 2 Grinding Stone 3 Rod 4 Radial Needle Bearing 5 Displacement Sensor 6 Workpiece 7 Circular Hole 8 Taper Guide 9 Guide 10 Cage 11 Needle 12 Outer Ring 13 Sleeve 14 Cylindrical Part 15 Flange Reference Signs List 16 Stopper 17 Urging spring 18 Holder 19 Axis 20 Swinging arm 21 Cutting blade 22 Urging spring 23 Pressing piece 24 Adjusting nut 25 Center hole 26 One side 27 Base other side 28 Base end one side 29 Female screw part 30 Engaged part 31 Main body 32 Taper cone 33 Pull rod 34 Rotary sleeve

Claims (3)

By processing the inner peripheral surface of the circular hole along with the rotation, a processing portion for processing the inner diameter of the circular hole to a desired value, A concentrically provided holding portion, a slide member supported by the holding portion for allowing axial movement while preventing movement in the radial direction, and detection means for detecting an axial displacement of the slide member Wherein the outer diameter of the slide member is defined as a lower limit of an allowable range of the inner diameter of the circular hole. The drilling tool according to claim 1, wherein the slide member is a rolling bearing that rotatably supports an outer ring around a holding portion by a plurality of rolling elements. 3. The drilling tool according to claim 1, wherein the detecting means comprises a sleeve for pressing the slide member toward the processing portion by a spring, and a sensor for detecting a position of the sleeve. .

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