JPH0318122Y2 - - Google Patents

Description

[Detailed description of the invention] a. Purpose of the invention (industrial application field) The grinder for grinding the tip of a bolt according to this invention is capable of detecting the presence or absence of defects occurring inside a large number of bolts used in bridge bolts, etc. Used when grinding the end of the bolt protruding from the nut for inspection.
The purpose is to perform grinding work efficiently and safely, and to obtain a good ground surface.

(Prior art) In the case of various large steel buildings such as bridge girders and television towers, which are constructed by combining steel frames and steel plates, a large number of bolts and nuts are used to connect the constituent members such as steel frames and steel plates. is used.

For example, when constructing a bridge, as shown in FIGS. 12 and 13, a large number of through holes drilled in two steel plates 1 and 1 are aligned with each other, and a large number of bolts 2 are inserted through each hole. , 2 and nuts 3, 3 and further tightened, the two steel plates 1, 1 are firmly joined to each other. Washers 4, 4 are held between each steel plate 1, 1 and the head 2a, 2a of the bolt 2, 2, or the nut 3, 3, respectively.

By the way, during long-term use, the bolts 2, 2, which are used to connect the components of a large building, may suffer from stress corrosion or metal fatigue, resulting in damage to the threaded portions with the nuts 3, 3. Cracks are likely to occur in areas where stress is concentrated, such as the trough of the male screw formed on the outer circumferential surface or the continuous area between the head 2a and the rod.

If the cracks that occur in this way are left untreated,
In the end, the bolt 2 was torn, and the torn bolt 2,
2 and this bolt 2, the nut 3 screwed into 2,
3 falls.

When bolts and nuts that connect structural members of a large building fall, not only does the strength of the bond between the structural members decrease, but the bolts and nuts that fall also hit people and vehicles passing below. Danger arises.

For this reason, the numerous bolts used in the assembly of large buildings have been periodically diagnosed for cracks, and if cracks have occurred, the bolts have been replaced before they break. I try to do it.

Previously, the method of inspecting for cracks was to identify the sound by hitting the bolt with a hammer, but this not only required skill, but also made it easy to identify the presence of cracks even if cracks had occurred. It was difficult to discover the wound until it had become quite large.

For this reason, in recent years, ultrasonic flaw detection testing methods have been adopted to solve the above-mentioned problems. The ultrasonic flaw detection test method, which has been widely used in recent years as a non-destructive testing method, tests for the presence of cracks by sending ultrasonic waves from the end of the bolt in the direction of the bolt's central axis. In this case, the presence or absence of a crack and its location can be determined by utilizing the fact that the ultrasonic waves sent from the end are reflected at the crack.

By the way, when using such an ultrasonic testing method to inspect the presence or absence of cracks in bolts and their locations, the end face of the bolt into which ultrasonic waves are sent is ground to a plane perpendicular to the center line of the bolt. There must be. If this grinding is uncertain, the ultrasonic waves sent from the end face of the bolt may not reach the crack, which impairs the reliability of determining the presence and location of cracks.

For this reason, conventionally, before inspecting for cracks using an ultrasonic flaw detector, the tip of the bolt to be inspected is ground using a general-purpose hand grinder.

(Problem that the invention aims to solve) However, when grinding the tip of a bolt using a general-purpose hand grinder as in the past, it is difficult to hold the heavy (usually around 5 kg) hand grinder.
It is dangerous to grind bolts such as those used for assembling bridges, which are located at high places (several tens of meters above the ground or water surface) and are oriented in any direction, such as sideways, downwards, or upwards. Not only that, but it is difficult to finish the end of the bolt to be ground into a flat surface perpendicular to its center line.

In other words, when carrying out grinding work with a general-purpose hand grinder in your hand, it is easier to grind by pressing the outer edge of a circular grindstone that rotates at high speed against the part to be ground. When the outer peripheral edge of a grindstone is pressed against the surface to be ground, it is inevitable that the grinding surface will curve into a concave or convex shape or be inclined.

If the ground surface is curved or inclined in a concave or convex shape, it becomes difficult to accurately determine the presence or absence of cracks using an ultrasonic flaw detector.

Furthermore, the bolts used for assembling large structures such as bridges are coated with paint, so when grinding the tips of these bolts, the paint must first be removed, but the If you remove this paint using a hand grinder, the paint will clog the grinding wheel, and unless you change the grinding wheel frequently, you will not be able to grind the bolts efficiently. .

The bolt tip grinder of the present invention eliminates all of the above-mentioned disadvantages.

b. Structure of the invention (means for solving problems) The bolt tip grinder of the invention grinds the tip of the bolt screwed into the nut, which protrudes from the nut, with respect to the center line of the bolt. It is used for grinding to a perpendicular plane.

That is, the bolt tip grinder of the present invention has a reference surface that can be brought into close contact with the plane on which the nut is tightened, and a mounting base that has a through hole into which the nut can be inserted.

A tightening screw is screwed into the screw hole whose both ends are opened at the outer peripheral surface of the mounting base and the inner peripheral surface of the through hole from the outer peripheral side of the mounting base. The outer circumferential surface of the nut can be pressed at the protruding tip.

Also, on the opposite side of the reference surface of the above mounting base,
A guide rod, which is perpendicular to the reference plane, is fixed via a bracket to a portion of the through hole that is removed from the extended portion.

A holding member is fitted onto the guide rod so as to be movable and rotatable in the length direction of the guide rod, and the grinder main body is further fixed to this holding member.

The rotating shaft of the grindstone is provided at one end of the grinder body so as to be able to face the head of the bolt.
It is parallel to the guide rod mentioned above.

(Function) When grinding the tip of a bolt for ultrasonic flaw detection using the bolt tip grinder of the present invention configured as described above, the work is carried out as follows. .

First, the nut that is threaded onto the bolt whose tip is to be ground is fitted into the through hole of the mounting base, and the reference surface of the mounting base is brought into close contact with the plane on which the nut is tightened. In this state, rotate the tightening screw screwed into the screw hole of this mounting base to increase the amount of protrusion of this tightening screw from the inner circumferential surface of the above-mentioned through hole, and the tip of this tightening screw The mounting base is inseparably connected to the nut by pressing the outer peripheral surface of the nut.

By inseparably connecting the mounting base to the nut,
Once the guide rod is fixed perpendicular to the plane on which the nut is tightened, and the bolt screwed into this nut and the guide rod are fixed parallel to each other, the By moving the circular grindstone to a position slightly away from the tip of the bolt to be ground, and then sliding the holding member against the guide rod, the part near the end of the grindstone and the tip of the bolt are separated. However, the state is such that they can collide a little.

From this state, when the holding member is rotated back and forth with respect to the guide rod, the tip of the bolt is ground by the grindstone of the grinder body. In this case, the grinding is initially performed on the outer circumferential surface of the circular grindstone, and then on the flat end surface. For this reason, the end face of the bolt after grinding becomes flat without being curved.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

Figures 1 to 3 show the first embodiment of the present invention, with Figure 1 being a partial longitudinal side view and Figure 2 being a plan view.
FIG. 3 is a sectional view taken along the line AA in FIG. 1.

In Fig. 1, reference numeral 5 denotes a mounting base, and the lower surface of this mounting base 5 (top, bottom, left, and right are according to the drawings).Since the grinder of the present invention is used in any posture, depending on the usage condition, the description of the embodiment may be ) is a flat reference surface 6, and this reference surface 6 is used as a plane on which the nut 3 to which the bolt 2 to be ground is screwed is tightened (for example, in FIGS. 12 and 13). side of steel plate 1)
I am free to work closely with.

Such a mounting base 5 includes a base main body 8 having a circular notch 7, a plate member 10 that is fixed to the base main body 8 by screws 9, and closes the opening of the notch 7. The portion surrounded by the inner peripheral surface of the notch 7 and the side surface of the plate material 10 is a through hole 11 into which the nut 3 is fitted. However, the plate material 1 around the opening on the reference surface 6 side of the through hole 11
0 and the base body 8 are formed with a notch or a recess for the washer 4 to escape, so that the reference surface 6 of the mounting base 5 and the flat side surface of the steel plate 1 can be brought into close contact. .

A screw hole 12 is formed on the side surface of the base body 8 at a position opposite to the opening of the notch 7, and both ends of the screw hole 12 are connected to the mounting base 5 formed by the base body 8 and the plate material 10. The outer peripheral surface and the inner peripheral surface of the through hole 11 are opened. A tightening screw 13 is screwed into the screw hole 12 from the outer peripheral side of the mounting base 8. A hemispherical recess 14 is formed on the tip end surface of the tightening screw 13 near the inner circumference, and a hemispherical abutment piece 15 is swingably fitted into this recess 14. The flat surface 15a of the nut 15 can freely come into contact with the outer peripheral surface of the nut 3 inserted into the through hole 11.

Further, a horizontal L-shaped bracket 16 is fixed to one end of the upper surface of the mounting base 5 by screws 17, 17, and a bracket 16 is attached at a right angle to the reference plane 6 at the tip of the bracket 16. Naru guide rod 18
The lower end of is fixed with screws.

A cylindrical holding member 1 is provided in the middle part of the guide rod 18.
9 is externally fitted through sleeves 35, 35 so that it can move up and down and rotate freely with respect to the guide rod 18. A retaining ring 20 in the form of an outward flange is fixed to the upper outer peripheral surface of the guide rod 18, and a compression spring 21 is provided between the lower surface of the holding member 19 and the upper surface of the bracket 16, so that the holding member 19 is It is elastically pressed toward the lower surface of the retaining ring 20.

Also, a pair of upper and lower sleeves 23, 23 are held between the upper surface of the retaining ring 20 and the lower surface of the retaining nut 22 screwed and fixed to the upper end of the guide rod 18.
In addition, a vertically extending through hole 25 is formed at the tip (right end in FIG. 1) of the rotary arm 24, which is fitted externally so that it can only rotate freely, and an adjustment screw 26 is inserted into this through hole 25. The upper end portion is rotatably supported via sleeves 27, 27. A male screw portion 29 formed on the lower outer peripheral surface of the adjustment screw 26 can be manually rotated in the torsional direction by a knob 28 fixed to the upper end portion protruding from the upper surface of the rotating arm 24. An elevating piece 31 having a rectangular notch 30 formed on the opposing side surface is screwed onto the elevating piece 31. On the other hand, on the side surface of the holding member 19, the adjusting screw 2
A guide rail 32 extending in the vertical direction is formed in a portion facing 6, and this guide rail 32
However, in the notch 30 formed in the lifting piece 31,
They are slidably fitted.

The lifting piece 31 is formed with a screw hole 33 that opens at one end on the inner surface of the notch 30 and at the other end on the outer side of the lifting piece 31.
A fixing screw 34 having a fixed screw 6 is screwed into this screw hole 33 from the outer surface side of the elevating piece 31.
Therefore, the tip of the fixing screw 34 comes into contact with the side surface of the guide rail 32 and moves away from the side surface as the knob 36 rotates.

Furthermore, a holding part 37 is provided on the side surface of the holding member 19 at a position opposite to the adjustment screw 26, and a grinder main body 38 is held and fixed to this holding part 37.

From the bottom surface of this grinder main body 38, the main body 3
A rotary shaft 39 that is rotationally driven by a motor built in the rotary shaft 39 protrudes, and a circular grindstone 40 can be freely attached to the lower end of the rotary shaft 39.
The rotating shaft 39 is parallel to the guide rod 18 so that the lower surface of the grindstone 40 is perpendicular to the center line of the bolt 2 to be ground, and the center of the rotating shaft 39 is parallel to the guide rod 18. The distance from the center of the guide rod 18 is made approximately equal to the distance between the center line of the bolt 2 to be ground and the center line of the guide rod 18, so that the lower surface of the grindstone 40 can oppose the upper end of the bolt 2. ing.

Using the bolt tip grinder of the present invention constructed as described above, the operation for grinding the tip of a bolt in order to carry out the ultrasonic flaw detection method is carried out as follows.

First, the nut 3 screwed into the bolt 2 whose tip is to be ground is inserted into the circular through hole 11 of the mounting base 5, which is made up of the base body 8 and the plate material 10.
Further, the lower surface forming the reference surface 6 of the mounting base 5 is brought into close contact with the plane on which the nut 3 is tightened (the side surface of the steel plate 1). At this time, the inner surface of the flat plate material 10 is opposed to any of the flat side surfaces of the hexagonal nut 3.

In this state, the tightening screw 13 screwed into the screw hole 12 of the mounting base 5 is rotated to increase the amount of protrusion of the tightening screw 13 from the inner circumferential surface of the through hole 11. A contact piece 15, which is swingably attached to the tip of the screw 13, is attached to the outer surface of the nut 3,
Abut against the surface opposite to the plate material 10. Contact piece 15
is abutted against the outer surface of the nut 3, and as a result, the nut 3 is pushed upward in FIG. 3, and as a reaction, the mounting base 5 moves downward in the same figure. Therefore, the flat inner surface of the plate 10 is strongly pressed against one side of the nut 3, and the abutting piece 15 is strongly pressed against the other side of the nut 3, and the nut 3 is strongly held between the plate 10 and the abutting piece 15. In this state, the mounting base 5 is inseparably connected to the nut 3.

When the mounting base 5 is inseparably connected to the nut 3 in this way, the bracket 16 is attached to the mounting base 5.
The guide rod 18 is fixed perpendicularly to the plane on which the nut 3 is tightened,
The bolt 2 screwed into this nut 3 and the guide rod 1
8 are fixed in parallel to each other.

Once the guide rod 18 has been fixed in this way, the grinder body 38 is moved above the bolt 2 to be ground, and the grinder body 38 is moved above the bolt 2 to be ground.
After the lower surface of the grindstone 40 attached to the lower end of the grinding wheel 8 is brought into contact with the upper end surface of the bolt 2, the fixing screw 34, which had been left in a loosened state until then, is tightened via the knob 36, and the holding member is tightened. By preventing the lifting piece 31 from sliding on the guide rail 32 of 19, the holding member 19 and the lifting piece 31 are integrally coupled.

After the holding member 19 and the elevating piece 31 are integrally connected with the upper end surface of the bolt 2 and the lower surface of the grindstone 40 aligned with each other, the holding member 19
is rotated relative to the guide rod 18, and the circular grindstone 40 provided at the lower end of the grinder main body 38 is moved to a position slightly away from the upper end of the bolt 2 to be ground.

Once the grindstone 40 has been retracted from above the bolt 2, the adjustment screw 26 is rotated in the twisting direction via the knob 28 fixed to the upper end of the adjustment screw 26. The lifting piece 31 is lowered, and as the fixing screw 34 is tightened, the holding member 19 integrally connected to the lifting piece 31 is lowered along the guide rod 18 against the compression spring 21. This amount of descent varies depending on the thickness and material of the bolt 2 whose tip is to be ground, but in the case of a bolt made of high-strength steel for large-sized bridges, the amount of descent at one time is approximately 0.25 mm. For this purpose, set the knob 28 to 1/4
Rotate it to some extent.

In this way, by lowering the holding member 19 against the elasticity of the compression spring 21, the part near the end face of the grindstone 40 attached to the lower end of the grinder body 38 fixed to the holding member 19 and the bolt to be ground are removed. 2 will be in a state where they can freely collide with each other.

In this state, if electricity is supplied to the grinder main body 38 to rotate the grindstone 40 and the holding member 19 is manually rotated back and forth with respect to the guide rod 18, the upper end of the bolt 2 will be attached to the grinder. The main body 38 is ground by a grindstone 40 attached to the lower end thereof.
In this way, when the holding member 19 is rotated back and forth, the grinding is initially performed on the outer peripheral edge of the circular grindstone 40, and then on the flat lower surface, so that the bolt The upper end surface of No. 2 is flat without being curved.

If the upper end surface of the bolt 2 is not sufficiently ground by one-time grinding, the holding member 19 is lowered little by little by rotating the knob 28, and the above-mentioned grinding operation is repeated.

Next, a second embodiment shown in FIGS. 4 and 5 will be described.

In this example, in order to grind the upper end of the bolt 2,
The holding member 19 to which the grinder main body 38 is fixed is
The work of rotating the guide rod 18 back and forth can be done automatically without manual intervention.

A support bracket 41 is fixed to the upper surface of the rotating arm 24, which is fitted around the upper part of the guide rod 18 fixed to the mounting base 5 via the bracket 16 so as to be able to rotate freely. 41
A motor 42, which can freely rotate in forward and reverse directions, is supported and fixed on the top surface.

The motor 42 is attached to the lower side of the motor 42.
The center of the output shaft 44 of the reducer 43 driven by is aligned with the center of the guide rod 18,
This output shaft 44 and the upper end of the guide rod 18 are coupled via a sliding joint 45.

A pin 46 as shown in FIG. 5 is fixed to the side surface of the upper end of the guide rod 18 in a protruding manner, and is placed in a position where it can collide with the pin 46 on the upper surface of a support plate 47 fixed to the rotating arm 24. A pair of microswitches 48, 48 are fixed at a distance.

The basic operation when grinding the upper end of a bolt using the grinder of this example is as follows:
As in the case of the first embodiment described above, when the holding member 19 is rotated with respect to the guide rod 18,
When the motor 42 is energized, the output shaft 4 of the reducer 43
4, the rotating arm 24 rotates in a direction opposite to the rotational direction of the output shaft 44. When the rotating arm 24 rotates by more than a certain angle, the micro switch 48, which does not move with respect to the rotating arm 24, is pushed by the pin 46, which does not move with respect to the guide rod 18, and as a result, the rotation direction of the motor 42 is changed. Therefore, the rotating arm 24 can rotate back and forth without any manual intervention.

If the grinding resistance between the grinding wheel 40 and the upper end of the bolt 2 becomes too large due to reasons such as the lowering amount of the holding member 19 due to the rotation of the adjustment screw 26 being too large, or if the grinding resistance between the grinding wheel 40 and the upper end of the bolt 2 becomes too large. When an impact is applied, the sliding joint 45 slips, causing the rotating arm 24 to rotate at a speed commensurate with the load, which may cause the rotating arm 24 to rotate forcefully and damage the grindstone 40. To prevent.
Also, in the unlikely event that the micro switch 48 is
In the event of malfunction of the motor 42 or overrun of the motor 42, the sliding joint 45 slips to prevent the rotating arm 24 from rotating further than the rotating end.

Next, FIGS. 6 and 7 show a third embodiment of the present invention.

In the case of this embodiment, a motor incorporated in the grinder body 38 and rotating the grinding wheel 40 is used.
The holding member 19 is configured to be able to reciprocate and rotate, and also to be automatically lowered along with this reciprocating rotation.

That is, a reducer 49 driven by a motor for rotationally driving the grindstone 40 is mounted on the upper part of the grinder main body 38.
A cam body 51 is fixed to the output shaft 50 of 9.

On the upper surface of the cam body 51, the other end of the connecting arm 52 is pivotally supported at a position away from the center of rotation by the output shaft 50, and the other end of the connecting arm 52 is connected to the upper end surface of the guide rod 18 on which the holding member 19 is rotatably fitted. The cam arm 65 is pivotally supported at the distal end of a cam arm 65 whose base end is fixed to the cam arm 65.

On the other hand, a pin 53 as shown in FIG.
A pair of microswitches 55, 55 are fixed at a spaced apart position where they can freely collide with each other.

Further, the output shaft 5 of a reducer 57 is driven by a motor 56 fixed to the upper surface of the upper plate portion of the rotating arm 24.
8 and the upper end of the adjusting screw 26 which is rotatably supported on the lower plate of the rotary arm 24 are connected via an electromagnetic clutch 64, and this electromagnetic clutch 64 connects the microswitch 55, 55
is connected for a certain period of time only when the pin 53 is pressed, and the rotational force of the motor 56 is adjusted by the adjusting screw 26.
, and the holding member 19 is lowered by a certain amount via the elevating piece 31.

The basic operation when grinding the upper end of a bolt using the grinder of this example is as follows:
This is the same as in the first and second embodiments described above, but
In the case of this embodiment, the grindstone 40 of the grinder main body 38
When the grinder main body 38 is rotated, the connecting arm 52 that connects the cam body 51 rotating above the grinder main body 38 and the cam arm 65 fixed to the upper end of the guide rod 18 is pushed and pulled, and the grinder main body 38 A holding member 19 holding and fixing the holder 19 rotates back and forth around the guide rod 18.

Along with such reciprocating rotation of the holding member 19,
Micro switch 5 fixed to rotating arm 24
5 and 55 are pushed by a pin 53 fixed to the guide rod 18, and each time the holding member 19 is lowered little by little, the grindstone 40 of the grinder body 38 comes into contact with the upper end of the bolt 2.

In each of the embodiments described above, the guide rod is fixed using only one nut 3 among the many nuts 3, 3 lined up on the side surface of the steel plate 1 of a large building such as a bridge. However, if you want to securely fix the mounting base 5 due to reasons such as using a relatively large grinder body 38, it is possible to fix the mounting base 5 more securely as shown in FIGS. 8 and 9. Alternatively, the mounting base 5 can be fixed using two adjacent nuts 3, 3.

That is, in the case of the mounting base 5 used in this case,
Two large and small circular holes 59 and 60 are bored to match the pitch of two adjacent nuts 3 and 3. Among these, the small circular hole 60 has a size that allows the nut 3 to be fitted into the inside without rattling, and the large circular hole 59 has a nut 3 in the center.
A ring body 61 having a circular hole that can be fitted freely without rattling.
is fitted so that it can be moved slightly in the direction in which the reference surface 6 extends.

A screw hole 12 is formed at one end of the mounting base 5 on the opposite side from the small circular hole 60, and has both ends opened at the outer circumferential surface of the mounting base 5 and the inner circumferential surface of the large circular hole 59. A tightening screw 13 is screwed into the screw hole 12 from the outer peripheral surface side of the mounting base 5.

The bracket 16 for fixing the guide rod 18 is
It is fixed in the middle part of both circular holes 59, 60 so that the center of gravity of the entire grinder of the present invention is located on a perpendicular line passing between two adjacent nuts 3, 3.

When fixing the mounting base 5 having such a structure by spanning two adjacent nuts 3, 3, place one nut 3 inside the small circular hole 60 and the other nut 3 inside the large circular hole 59. Ring body 61 fitted inside
Insert each one inside.

If the tightening screw 13 is rotated from this state and the amount by which the tip of the tightening screw 13 protrudes from the inner peripheral surface of the large circular hole 59 is increased, the ring body 61 will move to the right in FIGS. The ring body 61 is pressed against the left side surface of one nut 3, and as a reaction, the mounting base 5 moves to the left in FIGS. is pressed against the right side of nut 3.

As a result, the mounting base 5 is tightly coupled and fixed to the two adjacent nuts 3, 3.

In order to make this connection and fixation more reliable, magnets 62, 62 are attached to the sides of the mounting base 5, as shown in FIG. The end surfaces of the magnets 62, 62 can also be attracted to the side surface of the steel plate 1 by positioning the surfaces 6 on the same plane.

Furthermore, in order to prevent the grinding work from being performed while the reference surface 6 of the mounting base 5 and the side surface of the steel plate 1 are not in close contact with each other, as shown in FIG. It is also possible to provide a microswitch 63 whose contacts are closed by a microswitch 63 so that the grinder main body 38 is not driven unless the contacts of this microswitch 63 are closed.

In addition to electricity, compressed air can also be used as the drive source for the grinder body 38.

Further, in each embodiment, if a transparent cover is provided around the grindstone 40 attached to the grinder main body 38, when the grindstone 40 is broken, the fragments will not be scattered around, making it safe.

c. Effects of the invention The bolt tip grinder of the present invention is configured and operates as described above, so it can be used in large numbers (for example, in the case of large hashikomo, the total number reaches tens to hundreds of thousands of bolts, so it is possible to Even if you were to conduct a sampling inspection of 10% of the total number of bolts, the number would be quite large.) This makes it easier to grind the heads of bolts in places with poor conditions such as high places, and also reduces the effects of clogging with paint. A good ground surface can be obtained without curving the ground surface, and highly reliable ultrasonic flaw detection tests can be performed.

[Brief explanation of drawings]

Figures 1 to 3 show the first embodiment of the present invention, with Figure 1 being a partial longitudinal side view and Figure 2 being a plan view.
3 is a sectional view taken along the line A-A in FIG. 1, FIGS. 4 and 5 show a second embodiment of the present invention, FIG. -B sectional view, 6th
Figures 7 to 7 show the third embodiment of the present invention, and the sixth embodiment
The figure is a partial vertical side view, Figure 7 is a plan view, and Figures 8 to 9
The figures show another example of the mounting base, Fig. 8 is a vertical side view, Fig. 9 is a plan view, Fig. 10 is a plan view showing a state in which a magnet is attached to it, and Fig. 11 is a mounting base. FIGS. 12 and 13 are vertical cross-sectional views showing the mounting portion of the microswitch for detecting the mounting state of the base, and show the arrangement of bolts whose tips are ground by the grinder of the present invention. 13 is a cross-sectional plan view, and FIG. 13 is a side view. 1... Steel plate, 2... Bolt, 2a... Head, 3
...Nut, 4...Washer, 5...Mounting base, 6...
... Reference surface, 7 ... Notch, 8 ... Base main body, 9 ...
...Screw, 10...Plate material, 11...Through hole, 12...
Screw hole, 13... Tightening screw, 14... Recess, 15
... Contact piece, 15a ... Flat surface, 16 ... Bracket, 17 ... Screw, 18 ... Guide rod, 19 ...
Holding member, 20... retaining ring, 21... compression spring,
22...lock nut, 23...sleeve, 24...
...Rotating arm, 25...Through hole, 26...Adjustment screw, 2
7... Sleeve, 28... Knob, 29... Male thread, 30... Notch, 31... Elevating piece, 32...
Guide rail, 33...screw hole, 34...fixing screw, 35...sleeve, 36...knob, 37...
Holding part, 38... Grinder body, 39... Rotating shaft, 40... Grindstone, 41... Support bracket, 4
2...Motor, 43...Reducer, 44...Output shaft, 45...Slip joint, 46...Pin, 47...
Support plate, 48...Micro switch, 49...Reducer, 50...Output shaft, 51...Cam body, 52...
...Connection arm, 53...Pin, 54...Support plate, 55
...Micro switch, 56...Motor, 57...
...reduction gear, 58...output shaft, 59, 60...circular hole, 61...ring body, 62...magnet, 63...micro switch, 64...electromagnetic clutch, 65...
cam arm.

Claims (1)

[Scope of utility model registration request] A bolt tip grinder that grinds the tip of a bolt screwed into a nut that protrudes from the nut into a plane perpendicular to the center line of the bolt, and can be brought into close contact with the plane on which the nut is tightened. A mounting base having a reference surface and a through hole into which the nut can be inserted, and a screw hole whose both ends are opened to the outer peripheral surface of the mounting base and the inner peripheral surface of the through hole from the outer peripheral side of the mounting base. a tightening screw that is screwed in and whose tip end closer to the inner circumference can freely press the outer circumferential surface of the nut, and a side opposite to the reference surface of the mounting base,
A guide rod is fixed to a portion outside the extension of the through hole via a bracket and is perpendicular to the reference plane, and the guide rod is provided with an external structure that is movable and rotatable in the length direction of the guide rod. A bolt tip consisting of a fitted holding member and a grinder body fixed to the holding member so that the rotating shaft of a grindstone, which is provided at one end so as to be able to face the tip of the bolt, is parallel to the guide rod. Grinder for grinding.