JP2009202320A - Method and device for manufacturing minute tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide method and device for manufacturing a minute tool capable of easily manufacturing the minute tool. <P>SOLUTION: In this method for manufacturing the minute tool 100, a composite structure tool 3 is formed by making an outer peripheral part of a rod-shaped tool body 1 from a material different from that of the rod-shaped tool body 1 and being coated with a clad material 2 having a material which is easier to be removed and formed from the rod-shaped tool body 1, a part of the clad material 2 of the composite structure tool 3 is removed, the rod-shaped tool body 1 is exposed by a required length, and thereby the minute tool 100 is manufactured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

    The present invention relates to a fine tool manufacturing method and a fine tool manufacturing apparatus, and more particularly to a fine tool manufacturing method and a fine tool manufacturing apparatus capable of easily manufacturing a fine tool.

Conventionally, for example, when electric discharge machining is applied to micromachining, a method of embedding and gripping a fine shaft in a hollow pipe has been used, but there is a problem that a great burden is imposed on selection and centering of the pipe. It was.
Alternatively, as another method, a round bar having a grippable diameter is gripped by a chuck, and then a micro shaft having a required micro diameter is formed in advance on the machine.
Conventionally proposed methods for forming a fine shaft include a reverse discharge method and a WEDG method.
Recently, a discharge micro-axis forming method using a machining hole (for example, see Patent Document 1), micro-axis forming by scanning micro-discharge machining (for example, see Patent Document 2), and the like have been proposed.
In these micro-shaft forming methods, since a round bar made of a material with small tool consumption suitable for original micromachining is used, it takes a lot of time in the micro-shaft forming process. Although there is a method for instantly forming a fine axis by single discharge, there is a problem that it is difficult to secure a central axis and a required axis diameter.
Further, as a method of forming a high-speed discharge fine axis using a machined hole, there is a fine machining with a zinc alloy electrode (see, for example, Patent Document 3). However, since the tool part to be formed is the original zinc alloy, the fine machining is performed. It is not suitable for normal processing because of excessive wear.
JP 2004-142087 A Japanese Patent Application No. 2005-331656 JP 2003-136337 A, JP 2004-314260 A

    It is an object of the present invention to provide a method for manufacturing a fine tool and a device for manufacturing a fine tool that eliminate the above-mentioned problems.

    The method for manufacturing a fine tool according to the present invention includes an outer peripheral portion of a rod-shaped tool body such as electric discharge machining, electrolytic machining, cutting, grinding, etc. made of a material different from the rod-shaped tool body, and removed from the rod-shaped tool body. A composite tool is formed by coating with a clad material that is easy to fabricate, and a part of the clad material of the composite structure tool is removed to expose the rod-shaped tool body to a required length to produce a fine tool. Is.

In the method for manufacturing a fine tool according to claim 2, the outer peripheral portions of the plurality of bar-shaped tool bodies arranged in parallel are made of a material different from that of the plurality of bar-shaped tool bodies, and are removed from the bar-shaped tool bodies. A composite structure tool is formed by covering with an easy clad material, and a part of the clad material of the composite structure tool is removed to expose the plurality of rod-shaped tool bodies to a necessary length to produce a fine tool. It is.

The method for producing a fine tool according to claim 3 is the method for producing a fine tool according to claim 1 or 2, wherein the clad material is a low melting point metal having a lower melting point or sublimation point than the material of the rod-shaped tool body, Metal powder, plastic resin, transparent plastic, light curable resin, or low sublimation temperature material.

The method for manufacturing a fine tool according to claim 4 is the method for manufacturing a fine tool according to claim 1 or 2, wherein the material of the rod-shaped tool body is tungsten, molybdenum, copper, brass, copper higher than the melting point of the clad material. A high melting point high thermal conductivity material such as tungsten, silver tungsten or tungsten carbide is used to function as an electrode for electric discharge machining.

The method for producing a fine tool according to claim 5 is the method for producing a fine tool according to claim 1 or 2, wherein the rod-shaped tool body is made of an antioxidant material such as iridium or platinum iridium, silicon, nickel alloy, or the like. The surface modifying material, a fine cutting tool made of a high hardness material, or a fine electrodeposition grindstone made of a high hardness material.

The method for manufacturing a fine tool according to claim 6 is the method for manufacturing a fine tool according to claim 1 or 2, wherein the material of the rod-shaped tool body is a high-hardness material whose hardness is higher than that of the clad material.

The method for manufacturing a fine tool according to claim 7 is the method for manufacturing a fine tool according to any one of claims 1 to 6, wherein the processing means for removing a part of the clad material of the composite structure tool is electrical discharge machining, Any one of single discharge, electrolytic machining, a method of immersing in a liquid having a temperature higher than the melting temperature of the clad material and lower than the material of the rod-shaped tool body, or laser processing.

    The manufacturing apparatus for a fine tool according to claim 8 is configured such that an outer peripheral portion of a rod-shaped tool main body such as electric discharge machining, electrolytic machining, cutting processing, and grinding processing is made of a material different from the rod-shaped tool main body, and the rod-shaped tool main body. A gripping part that covers a composite structure tool that is covered with a clad material that is easy to remove from the main body, and a part of the clad material of the composite structure tool that is gripped by the gripping part to remove the rod-shaped tool And processing means for exposing the main body to a necessary length.

According to a ninth aspect of the present invention, there is provided the fine tool manufacturing apparatus, wherein the outer peripheral portions of the plurality of bar-shaped tool bodies arranged in parallel are made of a material different from the plurality of bar-shaped tool bodies, and are removed from the bar-shaped tool bodies. A gripping part that is covered with an easy clad material and grips the composite structure tool;
Processing means for removing a part of the clad material of the composite structure tool gripped by the gripping portion and exposing the bar-shaped tool body to a required length is provided.

According to the method for producing a fine tool of the present invention, the outer peripheral portion of the rod-shaped tool body such as electric discharge machining, electrolytic machining, cutting, grinding, etc. is made of a material different from the rod-shaped tool body, and from the rod-shaped tool body. A composite structure tool is formed by coating with a clad material that is easy to remove and mold, and a part of the clad material of the composite structure tool is removed to expose the rod-shaped tool body to a required length to form a fine tool. In order to manufacture, a fine tool can be easily manufactured by exposing (peeling) the fine tool.
Usually, it has a grip part that is integrally manufactured from the same material as the fine tool body material, but there is a limit to the miniaturization of the tool part as an external setup. Therefore, the tip of the tool electrode having the same diameter as that of the gripping part is formed on the machine, but in this case, it takes time and cost to make the tool finer than processing by the formed fine tool. According to the present invention in which a commercially available fine wire is covered with a clad material, a significant improvement in efficiency and a reduction in cost can be achieved.

A fine tool manufacturing method and a fine tool manufacturing apparatus according to an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1A, 1 is a rod-shaped tool body such as electric discharge machining, electrolytic machining, cutting, and grinding, and 2 is an outer peripheral portion of the rod-shaped tool body 1 made of a material different from that of the rod-shaped tool body 1. At the same time, the composite tool 3 is formed by covering with a clad material 2 which is easier to remove and form than the rod-shaped tool body 1.
In FIGS. 1B and 1C, reference numeral 10 denotes a main part of the fine tool manufacturing apparatus, and reference numeral 11 denotes a holding part (for example, a collet chuck) for holding the composite structure tool 3. .

After the formation of the composite structure tool 3 described above, “electric discharge machining”, “single discharge”, “electrolytic machining”, “temperature higher than the melting temperature of the clad material and lower than the material of the rod-shaped tool body, which will be described later. A part of the clad material 2 of the composite structure tool 3 is removed by processing means such as “immersing in a liquid” or “laser processing” to expose the rod-shaped tool body 1 to a required length (for example, 1 mm) and fine. The tool 100 is manufactured [FIG. 1 (d)].
In other words, after being gripped by a gripping part (for example, a collet chuck) 11 of a processing machine, processing is performed by exposing (peeling) a processing tool part serving as a cutting blade by a necessary length on the machine or by external setup. It is.
That is, a tool-shaped wire having a desired shaft diameter made of an original tool material for fine machining is covered with a material that can be easily removed and molded, and if necessary, a rod-like tool at the cutting edge portion of the fine tool 100 It is a series of processing processes and apparatus for performing processing by exposing (peeling) a part of the main body 1 by a required length on the machine or by external setup.

The diameter of the bar-shaped tool body 1 is, for example, about 1 to 100 μm, and the material of the bar-shaped tool body 1 is higher than the melting point of the clad material 2 “tungsten, molybdenum, copper, brass, copper tungsten, silver tungsten, tungsten. A material having a high melting point and a high thermal conductivity such as carbide may be used so as to function as an electrode for electric discharge machining.
Further, the material of the rod-shaped tool body 1 is harder than an antioxidant material such as iridium or platinum iridium (for example, an antioxidant material for air discharge), a surface modifying material such as silicon or nickel alloy, or a material of the clad material 2. Any one of a fine cutting tool made of a high hardness material having a high hardness and a fine electrodeposition grindstone made of a high hardness material having a higher hardness than the material of the clad material 2 may be used.
Further, the clad material 2 is a low melting point metal, metal powder, plastic resin, transparent plastic, photo-curing resin, or low sublimation temperature material (camphor) having a melting point or sublimation point lower than the material (core material) of the rod-shaped tool body 1. Or naphthalene).
Further, in order to facilitate gripping of the fine tool 100, the cutting blade portion, that is, the rod-shaped tool main body 1 is covered with the gripping material that is the clad material 2, and the necessary portion is exposed and processed. 100 parts of the exposed rod-shaped tool body 1 are used in the micromachining field using electric discharge machining, electrolytic machining, cutting machining, grinding machining, and the like.

The composite structure tool 3 described above is, for example, as shown in FIGS. 2 (a) and 2 (b), a clad material melted from an opening 23 provided in the upper part of detachable molds 21 and 22, for example, Put a low melting point metal, metal powder, plastic resin, transparent plastic, photo-curing resin, or low sublimation temperature material having a lower melting point than the material of the rod-shaped tool body 1 (for example, tungsten) to solidify the clad material 2. Form.
Table 1 below shows a composite structure tool 3 in which a tungsten rod-shaped tool body 1 is covered with a clad material 2 of a low melting point alloy having a melting point lower than that of tungsten.

Moreover, the composite structure tool 3 mentioned above is, for example, a plating film method, more specifically, as shown in FIG. 3A, the rod-shaped tool body 1 (the material of the rod-shaped tool body 1 is, for example, , Tungsten), and the surface of the rod-shaped tool body 1 can be formed by covering with a zinc clad material 2.
Reference numeral 30 denotes a molten zinc solution container.

Further, the composite structure tool 3 described above is not limited to the one shown in FIG. 3A, but includes metal ions (for example, zinc ions) of the cladding material to be coated, as shown in FIG. 3B. Put the rod-shaped material 2 'of the clad material to be coated in the liquid to make the cathode (-), and use the rod-shaped tool body 1 for the anode (+), connect a DC power supply between both electrodes and give a voltage The metal to be plated can be deposited by a reduction reaction at the cathode, and the surface of the rod-shaped tool body 1 can be coated with the zinc clad material 2.
In addition, 31 is a container of molten zinc liquid.

Further, the composite structure tool 3 described above is not limited to the above-described one, but as shown in FIGS. 4A and 4B, for example, a material of a clad material to be coated in a plasma state in a vacuum (for example, Tungsten) can be formed by an evaporation method in which an ion gas of tungsten is blown to the surface of the rod-shaped tool body 1.

Further, the composite structure tool 3 described above is not limited to the one shown in FIGS. 4A and 4B, but as shown in FIG. It can also be formed by “prototyping”.

Moreover, the fine tool 100 mentioned above forms the ditch | groove 34 tapering in the moving direction of the composite structure tool (-electrode) 3 rotating on the electrode (+ electrode) 33 surface, for example, as shown in FIG. In addition, a voltage is applied to both poles, and the rod-shaped tool body 1 is required by removing a part of the clad material 2 of the composite structure tool 3 by discharging the electrode 33 during the relative movement between the composite structure tool 3 and the electrode 33. It can be manufactured by being exposed to a length (for example, 1 mm) (scanning discharge machining to a solid material).

Further, the fine tool 100 is not limited to the one shown in FIG. 6, for example, as shown in FIG. 7, the moving direction of the composite structure tool (− electrode) 3 that rotates on the end face of the electrode (+ electrode) 35. A notch groove 36 that is tapered is formed, a voltage is applied to both poles, and a part of the clad material 2 of the composite structure tool 3 is discharged by the discharge of the electrode 35 during the relative movement between the composite structure tool 3 and the electrode 35. Can be manufactured by exposing the rod-shaped tool body 1 to a required length (for example, 1 mm) (peeling scanning electric discharge machining using an electrode end face).

Further, the fine tool 100 is not limited to the above-described one, and as shown in FIGS. 8A and 8B, the electric discharge machining wire 37 travels and is orthogonal to the electric discharge machining wire 37. The clad material 2 of the composite structure tool 3 moves relatively, and at the same time, heat is generated by discharging the electric discharge machining wire 37, and a part of the clad material 2 of the composite structure tool 3 is removed by the heat. The rod-shaped tool body 1 can also be manufactured by exposing it to the required length (wire electric discharge grinding peeling method).
Reference numerals 38, 39, and 40 are guide members that guide the electric discharge machining wire 37 to a predetermined portion.

Further, the fine tool 100 is not limited to the above description, and as shown in FIG. 9, a part of the clad material 2 of the composite structure tool 3 is removed by the electric discharge machining of the thin plate 41 and the composite structure tool 3. The rod-shaped tool body 1 can also be manufactured by exposing it to a required length (vertical scanning electric discharge machining to a thin plate surface).
Table 2 below shows micrographs of the fine tool 100 according to this example.

Further, the fine tool 100 is not limited to the one described above, and as shown in FIG. 10, the composite structure tool 3 and the thin plate 43 having the fine holes 42 move relatively, and at the same time, the composite structure tool 3 and The thin plate 43 is energized and discharged to generate heat, and the heat is used to remove a portion of the clad material 2 of the composite structure tool 3 so that the rod-shaped tool body 1 is exposed to the required length. Yes (vertical scanning electrical discharge machining to thin plate surface with fine holes).
Table 3 below shows micrographs of the fine tool 100 according to this example.

Further, the fine tool 100 is not limited to the above-described one, and as shown in FIG. 11, the clad material 2 of the composite structure tool 3 by a single discharge energy by a single discharge having a discharge current of several tens A and a discharge pulse width of several hundred μs. It is also possible to manufacture the rod-shaped tool body 1 by removing a part thereof to expose the required length (single discharge peeling method).
Here, “single discharge” means that the composite structure tool 3 and the electrode 44 are energized and discharged only once at a predetermined time with a predetermined discharge energy. The bar-shaped tool body 1 is exposed to the required length by removing the portion.

Further, the fine tool 100 is not limited to the one described above, and as shown in FIG. 12, a part of the clad material 2 of the composite structure tool 3 is removed by electrolytic processing to expose the rod-shaped tool body 1 to a necessary length. It can also be manufactured (electrolytic peeling method).
In this electrolytic processing, the container 45 is set as a negative pole, the composite structure tool 3 is set as a positive pole, the container 45 is filled with an electrolytic solution, and an electrolytic action is applied by applying a DC voltage.

Further, the fine tool 100 is not limited to the one described above, and as shown in FIG. 13, the container 46 has a temperature higher than the melting point of the clad material 2 (the clad material is, for example, a low melting point zinc alloy). Put a liquid (for example, hot water of 100 ° C. or less), immerse a part of the composite structure tool 3 in the liquid for a predetermined time (for example, several seconds), remove a part of the clad material 2 and remove the rod-shaped tool body (The rod-shaped tool main body is, for example, tungsten.) It can also be manufactured by exposing 1 to the required length (immersion melt peeling method).
If the above process is executed by applying ultrasonic vibration of several tens of kHz to the liquid 47, the surface tension of the molten liquid of the clad material 2 is lowered, and the exposure is completed very easily.

Further, the fine tool 100 is not limited to the one described above, and a part of the clad material 2 of the composite structure tool 3 is removed by laser processing using a laser beam emitted from the laser generator 50 as shown in FIG. The rod-shaped tool body 1 can also be manufactured by exposing it to the required length (laser heating peeling method).
An example of the fine electric discharge machining by the fine tool 100 described above is shown in Table 4 below. When the composite structure tool 3 described above is long, as shown in FIG. 15, the electric discharge machining wire 51 travels and the composite structure tool 3 moves relative to the direction orthogonal to the electric discharge machining wire 51. At the same time, heat is generated by discharging the electric discharge machining wire 51, and the composite structure tool 3 can be cut to a required length by the heat. Reference numerals 52 and 53 denote guide members for guiding the electric discharge machining wire 51 to a predetermined part.

Further, the fine tool 100 is not limited to the above-described one, and as shown in FIG. 16, the outer peripheral portions of the plurality of rod-shaped tool bodies 1, 1,. The composite tool 3 is formed by covering with a clad material 2 which is made of a material different from that of the rod-shaped tool body 1, 1. And a plurality of rod-shaped tool bodies 1, 1,... Are exposed to a necessary length.
That is, FIG. 16 shows, for example, a multi-electrode peeling tool (fine tool 100) prepared by aligning a number of tungsten fine wires (bar-shaped tool body 1) and casting them with, for example, a low melting point zinc alloy (cladding material 2). ).
17 (a) and 17 (b) show a multi-electrode peeling tool (fine tool 100) prepared by casting and coating with a low melting point zinc alloy (cladding material 2) without subjecting to a peeling process. 200 shows an example in which a number of fine holes are formed simultaneously by electric discharge machining. In this case, the low-melting point alloy portion as the cladding is remarkably consumed, so that the cladding portion 2 is retracted, and the fine tool 100 is automatically exposed and a large number of holes are formed. A microshaft forming plate 300 in the figure is a dummy electrode provided to eliminate the influence of electric discharge on the surface to be processed.

FIG. 1 schematically shows a manufacturing process of a fine tool manufacturing method according to an embodiment of the present invention. FIG. 1A is a schematic cross-section of a composite structure tool in which a rod-shaped tool body is covered with a clad material. FIG. 1B is a schematic cross-sectional view of a state in which the composite structure tool of FIG. 1A is gripped by a gripping portion of a processing machine, and FIG. 1C is a view of FIG. FIG. 1D is a schematic cross-sectional view of a composite structure tool of FIG. 1 with a part of the cladding material removed, and FIG. 1D is a schematic perspective view of a fine tool manufactured after the peeling process of FIG. FIG. FIG. 2 schematically shows a manufacturing process of the composite structure tool of FIG. 1, and FIG. 2 (a) shows that a clad material melted from an opening provided in an upper part of a mold that can be freely attached and separated is input. FIG. 2 (b) is a schematic perspective view of the composite structure tool separated from the mold of FIG. 2 (a). FIG. 3 schematically shows another embodiment different from the manufacturing process of the composite structure tool of FIG. 2, and FIG. 3 (a) is a schematic perspective view of the first embodiment by the plating coating method. FIG. 3 (b) is a schematic perspective view of a second embodiment by a plating film method different from FIG. 3 (a). FIG. 4 schematically shows another embodiment different from the manufacturing process of the composite structure tool of FIG. 3, and FIG. 4 (a) is a schematic perspective view of the intermediate process by the vapor deposition method. FIG. 4B is a schematic perspective view showing a state in which the rod-shaped tool body of FIG. 4A is covered with a clad material. FIG. 5 is a schematic perspective view of a composite structure tool according to the manufacturing method of another embodiment of FIG. FIG. 6 is a schematic perspective view showing a method for manufacturing a fine tool. FIG. 7 is a schematic perspective view showing a method of manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. FIG. 8A is a schematic perspective view showing a manufacturing method of a fine tool by the manufacturing method of another embodiment of FIG. 7, and FIG. 8B is a view of another embodiment of FIG. 8A. It is a schematic perspective view which shows the manufacturing method of the fine tool by a manufacturing method. 9 (a) and 9 (b) are schematic perspective views showing a method for manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. 8 (b). FIG. 9 (a) shows a state before electric discharge machining, and FIG. (B) shows each after electric discharge machining. 10 (a) and 10 (b) are schematic perspective views showing a method of manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. 9, and FIG. 10 (a) shows a state before electric discharge machining and FIG. 10 (b). Indicates after electric discharge machining. 11 (a) and 11 (b) are schematic perspective views showing a method of manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. 10, and FIG. 11 (a) shows a state before a single discharge, and FIG. Indicates after single discharge, respectively. 12 (a) and 12 (b) are schematic perspective views showing a method of manufacturing a fine tool according to the manufacturing method of the other embodiment of FIG. 11, and FIG. 12 (a) shows a state before electrolytic processing, and FIG. Indicates the state after electrolytic processing. FIG. 13 is a schematic perspective view showing a method of manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. FIG. 14 is a schematic perspective view showing a method for manufacturing a fine tool according to the manufacturing method of another embodiment of FIG. FIG. 15 is a schematic perspective view of the cutting method of the composite structure tool shown in FIG. FIG. 16 is a schematic perspective view of another fine tool of FIG. FIGS. 17 (a) and 17 (b) show a multi-electrode peeling tool prepared by casting and coating with a low melting point zinc alloy, directly through an electric discharge machining object without drilling, and simultaneously opening a number of fine holes. An example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bar-shaped tool main body 2 Clad material 3 Composite structure tool 100 Fine tool

Claims (9)

The outer periphery of the rod-shaped tool body, such as electric discharge machining, electrolytic machining, cutting, and grinding, is made of a material different from the rod-shaped tool body, and is covered with a clad material that is easier to remove and form than the rod-shaped tool body. Forming a composite structure tool, and removing a portion of the clad material of the composite structure tool to expose the rod-shaped tool body to a required length, thereby manufacturing a fine tool. . The outer peripheral portion of the plurality of rod-shaped tool bodies aligned in parallel is made of a material different from that of the plurality of rod-shaped tool bodies, and is covered with a clad material that is easier to remove and form than the rod-shaped tool bodies to form a composite structure tool. A method for manufacturing a fine tool, wherein a part of the clad material of the composite structure tool is removed to expose the plurality of rod-shaped tool bodies to a required length to manufacture a fine tool. The clad material is a low melting point metal, metal powder, plastic resin, transparent plastic, photo-curing resin, or low sublimation temperature material having a melting point or sublimation point lower than that of the rod-shaped tool body. Or the manufacturing method of the fine tool of 2. The material of the rod-shaped tool body is a high melting point high thermal conductivity material such as tungsten, molybdenum, copper, brass, copper tungsten, silver tungsten, tungsten carbide, etc., which is higher than the melting point of the cladding material, and functions as an electrode for electric discharge machining. The method for producing a fine tool according to claim 1 or 2, wherein The material of the rod-shaped tool body is an anti-oxidation material such as iridium or platinum iridium, a surface modifying material such as silicon or nickel alloy, a fine cutting tool made of a high hardness material, or a fine electrodeposition grindstone made of a high hardness material. The method for producing a fine tool according to claim 1 or 2, wherein the method is any one of the above. The method for manufacturing a fine tool according to claim 1 or 2, wherein the material of the rod-shaped tool body is a high-hardness material whose hardness is higher than that of the clad material. The machining means for removing a part of the clad material of the composite structure tool is immersed in a liquid having a temperature higher than the melting temperature of the electric discharge machining, single discharge, electrolytic machining, clad material and lower than the material of the rod-shaped tool body. The method for manufacturing a fine tool according to any one of claims 1 to 6, wherein the method is any one of a method and laser processing. The outer periphery of the rod-shaped tool body, such as electric discharge machining, electrolytic machining, cutting, and grinding, is made of a material different from the rod-shaped tool body, and is covered with a clad material that is easier to remove and form than the rod-shaped tool body. A gripping part for gripping the composite structure tool,
And a processing unit that removes a part of the clad material of the composite structure tool gripped by the gripping part and exposes the rod-shaped tool body to a required length. . The outer peripheral portion of the plurality of rod-shaped tool bodies aligned in parallel is made of a material different from that of the plurality of rod-shaped tool bodies, and is covered with a clad material that is easier to remove and form than the rod-shaped tool bodies to grip the composite structure tool. A gripping part;
And a processing unit that removes a part of the clad material of the composite structure tool gripped by the gripping part and exposes the rod-shaped tool body to a required length. .