Piercing tool

A piercing tool can be used by optionally replacing a distal end portion, which is to be first brought into abutment against an object to be pierced such as the ground, and can facilitate a replacement operation of the distal end portion. A piercing tool includes: a distal end portion, which has a cylindrical shape, and is to be first brought into abutment against an object; and a main body portion, which has a cylindrical shape at the main body portion, and has one end portion to which the distal end portion is mounted, wherein the distal end portion is removably mounted to the one end portion of the main body portion. The distal end portion has an inner peripheral surface having a female thread formed at an end portion of the distal end portion on a side to be mounted to the main body portion.

TECHNICAL FIELD

The present invention relates to a piercing tool, and more specifically, to a piercing tool to be used for operations such as perforation, boring, and punching, which are performed by piercing an object represented by the ground such as turf and a base material such as leather with the piercing tool and pulling out the piercing tool.

BACKGROUND ART

Hitherto, as a piercing tool referred to as a tine to be used for an operation such as perforation, which is performed by piercing the ground such as turf with the piercing tool and pulling out the piercing tool, those as described in Patent Literatures 1 to 3 below have been known, for example.

In Patent Literature 1, there is described a tine including a tine main body having a hollow cylindrical shape with an open distal end. The tine main body has an opening portion formed in a circumferential surface thereof so as to extend in a lengthwise direction of the tine main body. The opening portion has a circumferential angle of 180° or more and 210° or less with the center axis of the tine main body as a center.

Further, in Patent Literature 2, there is described a tine configured to perforate turf. The tine includes an insertion cylindrical portion, a cylindrical distal end portion, and a tubular cutting portion. The insertion cylindrical portion has a substantially cylindrical shape and includes a distal-end opening portion on a distal end side and an attaching portion on a proximal end side. The attaching portion is to be attached to an aeration apparatus. The insertion cylindrical portion is configured to discharge soil of the turf, which is introduced from the distal-end opening portion, from a side-surface opening portion formed in a side surface. The cylindrical distal end portion has an opening portion continuous with the distal-end opening portion arranged on the distal end side of the insertion cylindrical portion, and is configured to cut the soil of the turf. The tubular cutting portion has a shape obtained by raising an outer peripheral portion of the cylindrical distal end portion in a ring shape. An edge of the raised portion on the distal end side is formed so as to function as a portion of a blade for cutting. The tubular cutting portion is configured to cut the soil of the turf so as to have a diameter larger than that of the soil cut by the cylindrical distal end portion.

Further, in Patent Literature 3, there is described a tine including a main body, a tip blade, and a plurality of spiral stripes. The main body has a discharge port formed by cutting a part of a side peripheral surface of a cylindrical body having an opening portion at a distal end. The tip blade is formed to be tapered at the distal end of the main body so as to narrow the opening portion. The plurality of spiral stripes protrude spirally from the opening portion to the discharge port along an inner periphery of the main body. When the main body pierces the ground, the tine cuts roots of grass introduced into the main body from the opening portion with the tip blade by twisting the grass along the plurality of spiral stripes.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In such related-art piercing tools, a piercing operation is repeatedly performed on an object such as the ground, with the result that the distal end portion, which is to be first brought into abutment against the object, may be worn or partially broken.

However, in this case, in the related-art piercing tools, it is required to replace the whole piercing tool including the distal end portion to cope with the situation.

Further, in the related-art piercing tools, for example, when conditions such as a state, a geological condition, a thickness, and a material of the object such as the ground (turf or the like) differ at the time of performing the piercing operation on the object such as the ground, in view of performing the piercing operation stably in a more appropriate manner, it may be required to change a material of the piercing tool itself or a hole diameter or a shape of a distal end hole formed at the distal end portion.

However, even in this case, in the related-art piercing tools, there is no other choice but to replace the whole piercing tool including the distal end portion to cope with the situation.

The present invention provides a piercing tool which can be used by optionally replacing a distal end portion, which is to be first brought into abutment against an object to be pierced such as the ground, and can facilitate a replacement operation of the distal end portion.

Solution to Problem

According to a piercing tool of the present invention (1), there is provided a piercing tool, including: a distal end portion, which has a cylindrical shape, and is to be first brought into abutment against an object; and a main body portion, which has a cylindrical shape at at least a part of the main body portion, and has one end portion to which the distal end portion is mounted, wherein the distal end portion is removably mounted to the one end portion of the main body portion, and has an inner peripheral surface having a female thread formed at an end portion of the distal end portion on a side to be mounted to the main body portion, wherein the main body portion has an outer peripheral surface having a male thread formed so as to be engaged with the female thread at the end portion of the main body portion on a side to which the distal end portion is mounted, and wherein the distal end portion has a Rockwell hardness higher than a Rockwell hardness of the main body portion.

Further, according to the piercing tool of the present invention (2), in the piercing tool according to the invention (1) described above, the male thread includes an incomplete thread portion formed in an inner end portion area away from the one end portion of the main body portion.

According to the piercing tool of the present invention (3), in the piercing tool according to the invention (2) described above, the incomplete thread portion is a portion that engages with a part of the female thread of the distal end portion in a non-normal state, and is formed in a shape in which valleys of the male thread become shallower as being away from the one end portion of the main body portion.

According to the piercing tool of the present invention (4), in the piercing tool according to any one of the inventions (1) to (3) described above, the Rockwell hardness of the distal end portion is set within a range of from 59 or more and 64 or less, and the Rockwell hardness of the main body portion is set within a range of from 50 or more and 56 or less.

Further, according to the piercing tool of the present invention (5), in the piercing tool according to any one of the inventions (1) to (4) described above, the main body portion includes a wall surface portion that stops the end portion of the distal end portion through contact, and an outer peripheral surface portion having a groove shape in which the male thread is absent between the wall surface portion and the male thread.

According to the piercing tool of the present invention (6), in the piercing tool according to any one of the inventions (1) to (5) described above, the main body portion includes an outer peripheral surface portion having a cylindrical shape in which the male thread is absent at the end portion on the side to which the distal end portion is mounted, and the distal end portion includes an inner peripheral surface portion having an annular shape into which the outer peripheral surface portion having the cylindrical shape is fitted on a far side of the female thread in the inner peripheral surface in which the female thread is formed.

According to the piercing tool of the present invention (7), in the piercing tool according to any one of the inventions (1) to (6) described above, an outer peripheral surface of the distal end portion has an injection hole for injecting an adhesive, which penetrates through the outer peripheral surface of the distal end portion, formed in an area in which the female thread is present.

According to the piercing tool of the present invention (8), in the piercing tool according to any one of the inventions (1) to (7) described above, an outer peripheral surface of the distal end portion has a hook hole for inserting a projection of a hook spanner.

According to the piercing tool of the present invention (9), in the piercing tool according to any one of inventions (1) to (8) described above, the piercing tool includes, as the distal end portion, a plurality of distal end portions of different kinds that differ in one or both of a size and a shape of an opening of a distal end port to be first brought into abutment against the object, or a plurality of distal end portions of different kinds that differ in a material.

Advantageous Effects of Invention

According to the piercing tool of the invention (1) described above, the distal end portion is removably mounted to the one end portion of the main body portion, and the Rockwell hardness of the distal end portion is higher than the Rockwell hardness of the main body portion. Thus, the piercing tool can be used by optionally replacing the distal end portion, which is to be first brought into abutment against the object to be pierced such as the ground, and the replacement operation of the distal end portion can easily be performed.

With this, in the piercing tool, for example, even when the piercing operation is repeatedly performed on the object such as the ground, with the result that the distal end portion of the piercing tool is worn or partially broken, the distal end portion can be replaced with a new distal end portion to cope with the situation.

Further, in the piercing tool, for example, even when conditions such as a state, a geological condition, a thickness, and a material of the object such as the ground differ at the time of performing the piercing operation on the object such as the ground, the distal end portion can be replaced with a distal end portion of a kind of a material and a mode adapted to the state or the condition of the object to cope with the situation.

Further, in the piercing tool, when the distal end portion is to be replaced with a new distal end portion, for example, the distal end portion to be replaced is hit to apply impact so that cracks are easily formed in the distal end portion, thereby being capable of easily removing the distal end portion having the cracks formed therein from the main body portion.

According to the piercing tool of the invention (2) described above, the female thread of the distal end portion forcibly engages with the incomplete thread portion of the male thread of the main body portion so that the fastened state of the female thread and the male thread is less liable to be loosened. In addition, even when the fastened state starts to be loosened, the fear that the distal end portion is easily removed from the main body portion is reduced.

According to the piercing tool of the invention (3) described above, the fastening of the threads between the distal end portion and the main body portion can be made less liable to be loosened by the incomplete thread portion having a relatively simpler configuration.

According to the piercing tool of the invention (4) described above, it is possible to easily ensure the durability of the distal end portion and perform the replacement operation of the distal end portion.

According to the piercing tool of the invention (5) described above, the distal end portion can be mounted to the main body portion without any gap under a state in which the female thread of the distal end portion is securely fastened to the male thread of the main body portion.

According to the piercing tool of the invention (6) described above, when the distal end portion is to be mounted to the main body portion, the outer peripheral surface portion having an annular shape in the main body portion is fitted into the inner peripheral surface portion having an annular shape in the distal end portion, thereby being capable of rigidly mounting the distal end portion to the main body portion.

According to the piercing tool of the invention (7) described above, when the distal end portion is mounted to the main body portion, the female thread and the male thread can be bonded to each other with the adhesive, thereby being capable of more rigidly mounting the distal end portion to the main body portion.

According to the piercing tool of the invention (8) described above, when the distal end portion is to be mounted to or removed from the main body portion, with use of the hook spanner, the female thread and the male thread can be fastened or loosened easily and accurately. In particular, even when the incomplete thread portion is formed in the male thread, the female thread and the male thread can be fastened and loosened easily and accurately without damaging the distal end portion.

According to the piercing tool of the invention (9) described above, a distal end portion of a kind adapted to a state or a condition of the object can be selected, and hence the adapted distal end portion can be mounted to the main body portion, and the piercing tool can be used.

DESCRIPTION OF EMBODIMENTS

Now, embodiments of the present invention are described with reference to the attached drawings.

First Embodiment

InFIG.1(A),FIG.1(B), andFIG.2, a piercing tool according to a first embodiment of the present invention is illustrated.

As illustrated inFIG.1(A),FIG.1(B), andFIG.2, a piercing tool1according to the first embodiment includes a distal end portion2and a main body portion3. The distal end portion2is first brought into abutment against an object to be pierced. The main body portion3has one end portion to which the distal end portion2is to be mounted. In addition, the distal end portion2is removably mounted to the one end portion of the main body portion3.

Further, the piercing tool1is configured as, for example, a piercing tool, which is a so-called tine, to be used for an operation such as perforation, which is performed by piercing the ground such as turf being an example of the object with the piercing tool and pulling out the piercing tool.

The distal end portion2of the piercing tool1is a portion having a tapered cylindrical shape in appearance, and is made of, for example, a metal material.

The distal end portion2includes a main body21, a distal end port22, a connection port23, and a penetration space24. The main body21has a tapered hollow cylindrical shape. The distal end port22is formed at an end portion (distal end portion) of the main body21on a side to be first brought into abutment against the object. The connection port23is formed at an end portion (rear end portion) of the main body21on a side to be mounted to the main body portion3. The penetration space24passes through the main body21from the distal end port22to the connection port23.

Further, as illustrated inFIG.3(B)and other drawings, the distal end portion2has a female thread25formed at a part of an inner peripheral surface21bentering the penetration space24from the connection port23of the main body21.

Moreover, as illustrated inFIG.1(A),FIG.3(B), and other drawings, the distal end portion2has a hook hole26for inserting a projection63of a hook spanner6described later in an outer peripheral surface21aof the main body21.

The main body portion3in the piercing tool1is a portion having a substantially cylindrical shape in appearance, and is made of, for example, a metal material.

The main body portion3includes a main body31, a mounting portion32, an attaching portion33, a penetration space34, and an opening portion35. The main body31has a hollow and substantially cylindrical shape. The mounting portion32has a cylindrical shape and is formed at an end portion of the main body31on a side on which the distal end portion2is connected and mounted. The attaching portion33is formed at an end portion of the main body31on a side opposite to the mounting portion32so as to be attached to a component such as a holder or a device to which the piercing tool1is to be attached at the time of using the piercing tool1. The penetration space34passes through the main body31from the mounting portion32to the attaching portion33. The opening portion35is formed so as to cut out a part of the main body31along a longitudinal direction.

Further, as illustrated inFIG.1(A)toFIG.3(A), the main body portion3has a male thread36formed on an outer peripheral surface of the mounting portion32located at the one end portion. The male thread36is a thread that engages with the female thread25of the distal end portion2.

As illustrated inFIG.1(B)andFIG.3(A), the main body31of the main body portion3is a substantially cylindrical-shaped structure having a required length, and a required outer diameter K and a required inner diameter E1.

Further, as illustrated inFIG.1(B)andFIG.3(A), the mounting portion32of the main body portion3is a cylindrical-shaped portion having an outer diameter E3and the inner diameter E1, which protrudes from the one end portion of the main body31by a predetermined length M1. The mounting portion32is formed by, for example, cutting the one end portion of the main body31by cutting work. Therefore, the outer diameter E3of the mounting portion32is smaller than the outer diameter K of the main body31before the work (E3<K).

In the mounting portion32, the male thread36is formed to have a required thread length W1at the substantial center of the outer peripheral surface having the length M1. Further, the mounting portion32has an outer peripheral surface portion32ahaving a groove shape in which the male thread36is absent between the male thread36and the end portion of the main body31. Further, the mounting portion32has an outer peripheral surface portion32bhaving a cylindrical shape in which the male thread36is absent on a side opposite to the outer peripheral surface portion32awith respect to the male thread36. Further, one end of the mounting portion32is open and serves as one end of the penetration space34of the main body31. The reference symbol32cinFIG.1(B)and other drawings denotes an opening of the mounting portion32.

Both the outer peripheral surface portion32aand the outer peripheral surface portion32bare portions each formed of a cylindrical surface having an outer diameter E2(<E3) smaller than the original outer diameter E3of the mounting portion32. Further, the male thread36is formed such that valleys formed between thread ridges each have a depth substantially reaching a position of the outer diameter E2described above except for an incomplete thread portion37described later.

Further, as illustrated inFIG.1(B)andFIG.3(A), a step is formed between the main body31and the outer peripheral surface portion32a, and a wall surface portion formed by the step is formed as a wall surface portion38that stops a rear end portion of the distal end portion2through contact.

As illustrated inFIG.1(B)andFIG.2, the attaching portion33of the main body portion3uses an area of another end portion of the main body31having a hollow cylindrical shape at it is, and has a through hole39for causing a fixing component4such as a bolt described later to pass therethrough at a part of the attaching portion33.

Meanwhile, as illustrated inFIG.1(B)andFIG.3(B), the main body21of the distal end portion2is a cylindrical structure having a required length L and an outer diameter K at the end portion with the connection port23.

Further, the main body21has the penetration space24having a plurality of inner diameters. An inner diameter E2at the portion of the main body21into which the mounting portion32of the main body portion3is to be fitted at the time of mounting the distal end portion2to the main body portion3is set so as to have substantially the same dimensional relationship with the outer diameter E2of the mounting portion32. Further, the portion of the main body21into which the mounting portion32of the main body portion3is to be fitted is formed as a cylindrical-shaped inner peripheral surface having a length N1which is substantially equal to the length M1of the mounting portion32.

As illustrated inFIG.3(B), in the portion of the main body21into which the mounting portion32is to be fitted, the female thread25is formed to have a required length W2from the connection port23. The female thread25is formed of thread ridges which are spirally continuous at a required pitch. The two-dot chain lines inFIG.3(B)represent a part of the female thread25in the spirally continuous state.

Further, as illustrated inFIG.3(B), the portion of the main body21into which the mounting portion32is to be fitted has an inner peripheral surface portion27having an annular shape on a far side of the female thread25(side on which the distal end port22is formed). At least a part of the outer peripheral surface portion32bhaving a cylindrical shape in the mounting portion32of the main body portion3is to be fitted into inner peripheral surface portion27. The inner peripheral surface portion27is formed, for example, as a portion having a required length M2.

Further, the distal end port22of the main body21is formed as a circular opening portion having a required hole diameter D. The distal end port22is formed in the tapered distal end of the main body21, and hence the hole diameter D of the distal end port22is smaller than the inner diameter E2of the connection port23located on a side opposite to the distal end port22(D<E2). Further, the distal end port22is formed in such a shape that an edge portion thereof is sharpened in a tapered shape in cross section.

As exemplified inFIG.3(B), the penetration space24located on the distal end port22side of the main body21is formed as a cylindrical space continuous while having an inner diameter equal to the hole diameter D of the distal end port22. However, the penetration space24located on the distal end port22side is not limited to such a mode, and may be formed as, for example, a space having an inner peripheral surface shape whose inner diameter gradually changes so as to be substantially along the tapered shape in appearance of the main body21.

Further, one hook hole26in the outer peripheral surface21aof the distal end portion2is formed at a portion closer to the distal end port22with respect to the inner peripheral surface21bin which the female thread25is formed. The hook hole26is formed as, for example, a hole having a hole diameter and a depth that allow insertion of the projection63of the hook spanner6or the like as exemplified inFIG.6(A).

The hook spanner6is a kind of fastening tool. As illustrated inFIG.6(A), the hook spanner6includes acting portions61and62and projections63and64. The acting portions61and62are formed at both end portions of a plate-like member60so as to have a shape curved to be recessed inward. The projections63and64are formed at one end portions of the acting portions61and62so as to protrude. The acting portions61and62are formed as portions curved by arcs with curvature radii R1and R2set so as to correspond to the size of an object to be fastened. The hook spanner6is not limited to this configuration, and, for example, may include one acting portion.

Further, in the piercing tool1, the distal end portion2is formed so as to have the Rockwell hardness higher than the Rockwell hardness of the main body portion3.

The Rockwell hardness is the Rockwell hardness (HRC) measured by a Rockwell type hardness tester (manufactured by FUTURE-TECH CORP.: FR series). Specifically, the Rockwell hardness of the distal end portion2is measured by the model FR-1L of the Rockwell type hardness tester described above, and the Rockwell hardness of the main body portion3is measured by the model FR-1 of the Rockwell type hardness tester described above.

It is only required that the Rockwell hardness of the distal end portion2be hardness that allows cracks to be easily formed when the distal end portion2is hit by a hammering tool such as a hammer (having a weight in a range of from 1 to 2 pounds) by causing the hammering tool to naturally drop from a height of about 30 cm at the time of replacement of the distal end portion2(seeFIG.8(A)). Meanwhile, it is only required that the Rockwell hardness of the main body portion3be hardness that does not allow cracks to be formed or allows cracks to be less liable to be formed when the main body portion3is hit by the hammering tool such as a hammer similarly to the distal end portion2.

In this embodiment, the Rockwell hardness of the distal end portion2is set within a range of from 59 or more and 64 or less, and the Rockwell hardness of the main body portion3is set within a range of from 50 or more and 56 or less.

When the Rockwell hardness of the distal end portion2is less than 59, there is a trouble that the durability in a piercing operation is liable to be lowered, and the life of the product is liable to be shortened. In contrast, when the Rockwell hardness of the distal end portion2exceeds 64, there is a trouble that the toughness is lowered so that the distal end portion2becomes brittle, with the result that the distal end portion2is liable to be broken in the piercing operation.

It is preferred that the Rockwell hardness of the distal end portion2and the Rockwell hardness of the main body portion3be set to values within the above-mentioned ranges, for example, even when the outer diameter or the thickness differs in the distal end portion2and the main body portion3.

Further, in the piercing tool1, as illustrated inFIG.4in an enlarged manner, the male thread36of the main body portion3is formed as a thread portion including the incomplete thread portion37in addition to a complete thread portion360.

The incomplete thread portion37is formed in an end portion area in the thread length W1of the male thread36which is away from the end portion of the main body portion3on the side on which the distal end portion2is mounted. The incomplete thread portion37in the first embodiment is formed in such a shape that valleys36blocated between ridges36aof the male thread36become shallower as being away from the above-mentioned end portion of the main body portion3. A straight line J of the two-dot chain line illustrated in the circle of the one-dot chain line inFIG.4is an imaginary line passing through the bottoms of the valleys36badjacent to each other in the incomplete thread portion37.

Such an incomplete thread portion37is formed, for example, in a range corresponding to two to three pitches of the male thread36.

In the piercing tool1, the distal end portion2is mounted to or removed from the main body portion3as follows.

First, in mounting of the distal end portion2, as illustrated inFIG.5(A), the connection port23of the distal end portion2is brought closer to the mounting portion32of the main body portion3, and then, the distal end portion2is operated so as to be turned in the fastening direction of the threads.

In this case, in an initial stage, the female thread25in the distal end portion2engages with the complete thread portion360(FIG.4) of the male thread36in the main body portion3without any problem, and the distal end portion2moves so as to approach the main body portion3through the engagement of the threads.

Subsequently, when the female thread25in the distal end portion2reaches the incomplete thread portion37of the male thread36in the main body portion3, the female thread25becomes unable to engage with the incomplete thread portion37in a normal state due to the difference in the valley shape of the thread, and the distal end portion2receives resistance and is less liable to move.

After this stage, as exemplified inFIG.6(B), a mounting action is performed using the hook spanner6. That is, in this case, the projection63of the corresponding acting portion61of the hook spanner6is inserted into the hook hole26of the distal end portion2, and the acting portion61is brought into close contact with the outer peripheral surface of the distal end portion2. Then, the hook spanner6is turned in a required direction P being the fastening direction.

With this, the distal end portion2is turned by receiving a strong fastening action of the hook spanner6so that the female thread25obtains a strong propulsive force through engagement with the complete thread portion360of the male thread36.

As a result, as illustrated inFIG.5(B), the distal end portion2advances such that the female thread25in the distal end portion2forcibly climbs over the incomplete thread portion37of the male thread36in the main body portion3.

Finally, as illustrated inFIG.5(B), the distal end portion2stops after the edge portion of the connection port23comes into contact with the wall surface portion38which forms the step with the mounting portion32in the main body portion3.

At this time, a part of the female thread25in the distal end portion2which has already climbed over the incomplete thread portion37of the male thread36in the main body portion3is opposed to the outer peripheral surface portion32ahaving a groove shape in the mounting portion32of the main body portion3. Further, at this time, the inner peripheral surface portion27in the distal end portion2is slightly fitted to the outer peripheral surface portion32bhaving a cylindrical shape of the mounting portion32in the main body portion3. Further, at this time, the penetration space24in the distal end portion2and the penetration space34in the main body portion3are connected to each other in a continuous manner.

Thus, as illustrated inFIG.1(A)andFIG.5(B), the distal end portion2is assembled to the main body portion3by being mounted thereto without any gap. That is, the distal end portion2is assembled to the main body portion3so that the piercing tool1is assembled.

As described above, in the piercing tool1, the distal end portion2can easily be mounted to the main body portion3through the engagement between the female thread25and the male thread36.

Further, in the piercing tool1, at least a part of the female thread25in the distal end portion2is mounted to the incomplete thread portion37of the male thread36by forcibly engaging therewith in a non-normal state, and hence the piercing tool1has the structure in which the distal end portion2is less liable to be removed from the main body portion3. Therefore, in the piercing tool1, even when the threads start to be loosened during use such as abutment of the distal end portion2against an object, the distal end portion2is prevented from being easily turned in a loosening direction of the threads due to the presence of the engaged portion between the female thread25and the incomplete thread portion37, and there is no fear in that the distal end portion2is removed from the main body portion3.

Further, in the piercing tool1, even with the structure in which the incomplete thread portion37is present, when the distal end portion2is to be mounted to the main body portion3, a mounting operation can be performed using the hook spanner6. With this, the mounting operation can easily be performed without damaging the outer peripheral surface of the distal end portion2.

Next, as illustrated inFIG.6(B), the distal end portion2can be removed by turning the distal end portion2in the loosening direction of the threads using the hook spanner6.

With this, the distal end portion2is turned by receiving a strong turning action of the hook spanner6so that the female thread25obtains a strong propulsive force through the engagement with the complete thread portion37of the male thread36.

As a result, as illustrated inFIG.5(B), the distal end portion2advances such that the female thread25climbs over the incomplete thread portion37of the male thread36in the main body portion3.

Finally, as illustrated inFIG.1(B)and other drawings, the distal end portion2is removed from the mounting portion32of the main body portion3.

Thus, in the piercing portion1, the distal end portion2is removed and disassembled from the main body portion3.

As described above, in the piercing tool1, the distal end portion2can easily be removed from the main body portion3by releasing the engagement between the female thread25and the male thread36.

Further, the piercing tool1has a mechanism in which the distal end portion2is mounted by passing through the incomplete thread portion37in the male thread36. Therefore, even when the thread in the distal end portion2is temporarily loosened from the main body portion3, due to the presence of the incomplete thread portion37, there is no fear in that the distal end portion2easily turns in the loosening direction of the threads to be inadvertently removed from the main body portion3.

Moreover, in the piercing tool1, even with the structure in which the incomplete thread portion37is present, with use of the hook spanner6, the removing operation of the distal end portion2from the main body portion3can easily be performed.

As illustrated inFIG.7(B), the piercing tool1is used, for example, in a state of being mounted to a holding member5such as a holder.

As illustrated inFIG.7(A), the holding member5illustrated inFIG.7includes a holding main body50having an attaching hole51formed therein. The holding main body50has a required shape. The attaching portion33in the main body portion3of the piercing tool1is to be fitted into the attaching hole51. The attaching portion33of the piercing tool1is a portion having a hollow cylindrical shape, and hence the attaching hole51is formed as a hole having a cylindrical shape in which a support column portion52having a columnar shape is formed at the center portion. Further, one attaching hole51formed in the holding member5is illustrated inFIG.7(A). However, in general, a plurality of attaching holes51are formed in the holding member5.

Further, the holding member5has a fixing hole53. The fixing component4configured to fix the attaching portion33of the piercing tool1mounted to the attaching hole51is inserted into the fixing hole53and fixed. The fixing hole53is a hole penetrating to the attaching hole51and facing the support column portion52. Further, the fixing hole53is formed at a position facing the through hole39in the attaching portion33of the piercing tool1. Further, when the fixing component4is a screw, the fixing hole53has a female thread formed in the hole.

Moreover, the holding member5includes a mounting support column55for mounting the holding member5having the piercing tool1attached thereto to a device such as a perforator (not shown) configured to actually move the piercing tool1.

For example, a screw or the like is applied to the fixing member4. The fixing member4illustrated inFIG.7(A)includes a thread portion41and a head portion42. The thread portion41has a male thread formed thereon. The head portion42has a diameter larger than that of the thread portion41.

In attaching the piercing tool1to the holding member5, as illustrated inFIG.7(B), the attaching portion33of the piercing tool1is fitted into the attaching hole51. At this time, the support column portion52in the attaching hole enters an internal space (penetration space34) of the attaching portion33.

Subsequently, the fixing member4is inserted from the fixing hole53of the holding member5to pass through the through hole39of the attaching portion33of the piercing tool1so that the fixing member4is pressed against the support column portion52.

Thus, as illustrated inFIG.7(B), the piercing tool1is attached to the attaching hole51of the holding member5. Further, the holding member5having the piercing tool1attached thereto is mounted to a device such as a perforator (not shown).

Further, when the piercing tool1is to be removed from the holding member5, the piercing tool1can easily be removed from the attaching hole51of the holding member5by removing or loosening the fixing member4.

In using the piercing tool1, as exemplified inFIG.7(B), the piercing tool1is caused to pierce an object100such that distal end portion2is first brought into abutment against the object100, and then is moved so as to be pulled out.

For example, when the object100is the ground such as turf, the piercing tool1can be used for performing a perforating operation on the turf being the object100. Incidentally, at the time of the perforating operation, in the piercing tool1, roots of the grass or soil that enters the distal end hole22of the distal end portion2moves through the penetration space24of the distal end portion22to enter the penetration space34of the main body portion3, and is finally discharged to an outside through the opening portion35.

Further, in the piercing tool1, the piercing operation is repeatedly performed on the object100such as the ground in this manner, with the result that the distal end portion2, which is to be first brought into abutment against the object100, may be worn or partially broken.

In this case, in the piercing tool1, only the distal end portion2can be removed from the main body portion3and replaced with a new distal end portion2to cope with the situation. Further, the replacement operation can be performed on the piercing tool1attached to the holding member5without removing the piercing tool1from the holding member5.

Further, in the piercing tool1, it is difficult to remove the distal end portion2after use in the piercing operation or the like in some cases. The difficulty in removing the distal end portion2is caused, for example, because the distal end portion2is deformed due to the use, the engagement degree of the male thread36becomes stronger as compared with that in the initial stage, and it becomes difficult to loosen the engagement of the threads even by turning the distal end portion2with use of the hook spanner6.

However, in the piercing tool1, as illustrated inFIG.8(A), the distal end portion2which is difficult to be removed is hit from a height of, for example, about 30 cm, by a hammering tool65such as a hammer, thereby being capable of easily removing the distal end portion2from the main body portion3. That is, the distal end portion2of the piercing tool1has the Rockwell hardness relatively higher than that of the main body portion3, and hence a crack67is likely to be formed due to the impact. The reference symbol65ainFIG.8(A)denotes a hammer head portion, and the reference symbol65bdenotes a handle part including a grip portion.

Therefore, in the distal end portion2, the engagement of the threads is loosened due to the presence of the crack67. Thus, as illustrated inFIG.8(B), the distal end portion2can easily be removed from the main body portion3.

Therefore, in the case of using the piercing tool1, even when the distal end portion2is worn or partially broken, it is not required to replace the whole piercing tool1including the distal end portion2to cope with the situation. Further, such replacement can be performed while the piercing tool1is kept to be mounted to the holding member5, and hence it is not required to perform the operation of removing the piercing tool1from the holding member5.

Further, in the case of using the piercing tool1, even when the distal end portion2is difficult to be removed, the distal end portion2can easily be removed from the main body portion3, thereby being capable of easily performing the replacement operation of the distal end portion2.

Second Embodiment

InFIG.9(A)andFIG.9(B), a piercing tool1according to a second embodiment is illustrated.

The piercing tool1according to the second embodiment has the same configuration as that of the piercing tool1according to the first embodiment except that a distal end portion2B obtained by additionally forming an injection port28for injecting an adhesive in the distal end portion2is applied.

As illustrated inFIG.9(A), the injection port28is formed so as to penetrate to a part of the female thread25in the distal end portion2B. As illustrated inFIG.9(B), the shape and size of the hole of the injection port28are selected so as to correspond to the shape and size of, for example, an injection portion72of an injector7configured to store an adhesive105. The reference symbol71inFIG.9(B)denotes a storage portion configured to store the adhesive105. As the adhesive, for example, there is used an adhesive in a liquid state that exhibits an adhesive force to the extent that turning of the female thread25and the male thread36can be temporarily prevented with a small amount such as one drop or a few drops.

When the distal end portion2B having the injection port28formed therein is to be mounted to the main body portion3, as illustrated inFIG.9(B), the distal end portion2B is mounted to the main body portion3through fastening of the female thread25and the male thread36. Then, the injection portion72of the injector7is inserted into the injection port28, and the adhesive105in the injector7is injected.

With this, the female thread25and the male thread36can be bonded to each other with the adhesive105interposed in at least a part therebetween.

As a result, the distal end portion2B is more rigidly mounted to the main body portion3with the adhesive force by the adhesive105in addition to the fastening force of the female thread25and the male thread36.

Therefore, in the piercing tool1in which the distal end portion2B is applied, the distal end portion2B can be kept in a state of being less liable to be removed from the main body portion3.

Meanwhile, when the distal end portion2B is to be removed from the main body portion3, it is only required to turn the distal end portion2B under a state in which the distal end portion2B is heated from the outside to release the fastening between the female thread25and the male thread36.

Third Embodiment

InFIG.10(A), a piercing tool1according to a third embodiment is illustrated.

As illustrated inFIG.10(A), the piercing tool1according to the third embodiment has the same configuration as that of the piercing tool1according to the first embodiment except that a plurality of (two in this example) different kinds of distal end portions2C and2D that differ in the size of the opening of the distal end port22are provided.

Such piercing tool1including the plurality of distal end portions2C and2D provided in advance can be configured as a piercing tool kit. In the piercing tool kit, one main body portion3is provided and is used for the distal end portions2C and2D in common.

The distal end portion2C illustrated inFIG.10(A)has a circular distal end port22having a hole diameter D1, and the length of the distal end portion2C is a predetermined length L1. Meanwhile, the distal end portion2D illustrated inFIG.10(A)has a circular distal end port22having a hole diameter D2(>D1) larger than the hole diameter D1described above, and the length of the distal end portion2D is a length L2(<L1) smaller than the length L1.

Further, the distal end portion2C and the distal end portion2D differ only in the size of the distal end port22and the length of the distal end portion, and the other configurations are the same.

In the piercing tool1including such a plurality of distal end portions2C and2D, the distal end portion2C or2D of a kind having the distal end port22or the like whose size is adapted to a state or a condition of the object100is selected and can be used under a state of being mounted to the main body portion3. Further, the piercing tool1can be used while the distal end portion2C or2D is replaced with the other during use.

Further, as illustrated inFIG.10(B), the piercing tool1according to the third embodiment has the same configuration as that of the piercing tool1according to the first embodiment except that a plurality of (two in this example) different kinds of distal end portions2E and2F that differ in the shape of the opening of the distal end port22are provided.

Such piercing tool1including the plurality of distal end portions2E and2F provided in advance can also be configured as a piercing tool kit.

The distal end portion2E illustrated inFIG.10(B)has a circular distal end port22E. Meanwhile, the distal end portion2F illustrated inFIG.10(B)has a square distal end port22F.

Further, the distal end portion2E and the distal end portion2F differ only in the shape of the distal end port22, and the other configurations are the same.

In the piercing tool1including such a plurality of distal end portions2E and2F, the distal end portion2E or2F of a kind having the distal end port22E or22F whose shape is adapted to a state or a condition of the object100is selected and can be used under a state of being mounted to the main body portion3. Further, the piercing tool1can also be used while the distal end portion2E or2F is replaced with the other during use.

Modification Examples

The present invention is not limited to the configuration examples of the piercing tool1according to the above-mentioned first to third embodiments, and includes, for example, the following modification examples.

The configuration of mounting and removing the distal end portion2(including the distal end portions2B to2F) to and from the main body portion3in the piercing tool1is not limited to the configuration of fastening the female thread25and the male thread36to each other, and other coupling methods that enables mounting and removing can be employed without hindering the use of the piercing tool1.

Further, the configuration of the incomplete thread portion37in the male thread36is not limited to the configuration example in the first embodiment, and other configurations for forming the incomplete thread portion may be applied. Besides, formation of the incomplete thread portion37may be omitted as long as the distal end portion2can firmly be mounted. For example, in the piercing tool1according to the first embodiment, formation of the incomplete thread portion37can be omitted. Further, when formation of the incomplete thread portion37is omitted, for example, it is preferred that the injection port28for an adhesive be formed.

Further, when the distal end portion2is to be mounted or removed, the distal end portion2may be turned manually or using other tools without using the hook spanner6. In this case, for example, formation of the hook hole26in the outer peripheral surface21aof the distal end portion2can be omitted.

Further, in the distal end portion2, formation of the inner peripheral surface portion27, into which the outer peripheral surface portion32bhaving a cylindrical shape in the mounting portion32of the main body portion3is to be fitted, may be omitted. In this case, the operation of forming the inner peripheral surface portion27becomes unnecessary.

Further, other modes may be applied to the main body portion3of the piercing tool1as long as the main body portion3includes the mounting portion32to which the distal end portion2is to be mounted. Further, the attaching portion33of the main body portion3is not limited to the configuration example described in the first embodiment, and may have other configurations, for example, in consideration of adaptation to an attaching form in the holding member5or the like to which the piercing tool1is to be attached.

Further, the piercing tool including the plurality of distal end portions2may include a plurality of distal end portions of different kinds that differ in both the size and shape of the opening of the distal end port22. Moreover, the piercing tool including the plurality of distal end portions2may include a plurality of distal end portions of different kinds that differ in the material.

Besides, the piercing tool1may be configured as, for example, a piercing tool for performing a boring operation or a punching operation on the object100made of a base material such as leather. Further, the holding member5to which the piercing tool1is to be attached is not limited to the configuration described in the first embodiment, and, as a matter of course, may have other configurations including commercially available products of a form capable of attaching the piercing tool1.

REFERENCE SIGNS LIST