JP4454022B2 - U-shaped groove cutting device - Google Patents

Description

  The present invention is a concrete U-shaped groove in which a groove cover including a grating and other objects (hereinafter simply referred to as a groove cover) are mounted on the upper surface of a U-shaped groove having a different inner width and sidewall thickness. -It is related with the U-shaped groove cutting device for forming the mounting surface for accommodating.

In recent years, irrigation channels have been completely maintained by drainage grooves called concrete U-shaped grooves. At the same time, most of such U-shaped grooves that have been prepared especially in the early days are open-type, and the upper part thereof is often not covered with a grating, groove cover, or the like. However, as the traffic volume increases, it has been demanded that the open U-shaped groove contributes to ensuring road safety and expanding the road surface.
Furthermore, since this U-shaped groove was not intended to mount a groove lid at the beginning of manufacture, in order to mount the groove lid on the upper surface of this U-shaped groove, After excavating and securing a space where the formwork where the shape above the U-shaped groove should be changed can be installed, concrete for excising the upper part of the U-shaped groove, installing the formwork, and forming a new upper shape Therefore, a large amount of work and a lot of work were required, and a considerable construction period was spent.

  Here, there has been proposed a U-shaped groove cutting attachment that receives a hydraulic pressure source for cutting the U-shaped groove block from an external small excavator excavator (see, for example, Patent Document 1).

However, the purpose of the proposal of the device (attachment) is to process the U-shaped groove that is no longer needed, so that the U-shaped groove is filled with concrete or earth and covered with a lid. This is a proposal of an apparatus for cutting the upper part of the groove.
The apparatus seems to be effective when considering the entire work including the leveling work, but the cutting work itself has poor workability and cannot be said to have good work efficiency. Further, when the inner width lengths of the U-shaped grooves are different (for example, inner width lengths of 300 to 750 mm), it is impossible to cope with them unless other attachments that match the sizes and are different in performance are prepared. Further, when the inner width length of the U-shaped groove is small (for example, the inner width length is 300 mm) and the side wall is thick (for example, 100 to 200 mm), it is possible to cut completely from the relationship of the maximum cutting depth inherent to the cutting blade. In addition, there is a problem that it is difficult to maintain the height and level of the cutting position of both side walls of the U-shaped groove.

  Also, as another prior art, the existing U-shaped groove itself is used to automatically make the vertical cuts constituting the mounting step at the correct position and along the longitudinal direction of the U-shaped groove. In particular, an apparatus for forming a mounting step has been proposed (see, for example, Patent Document 2).

However, this device can cut the upper part of the U-shaped groove vertically, horizontally and diagonally with an electric concrete cutter, but the cutting of the U-shaped groove when the inner width length and the side wall thickness are different as described above. There is a problem that the work requires replacement with a cutting blade suitable for the size and change of the driving device (change of the motor output, reduction of the reduction gear ratio, etc.) associated therewith.
JP 2002-225027 A JP 2000-1836 A

The object of the present invention is to completely and easily cut the upper part of the side wall by simply replacing the cutting blade without increasing the output of the motor even when the inner width length of the U-shaped groove and the side wall thickness are different. It is another object of the present invention to provide a U-shaped groove cutting device that is compact without taking up space and that can keep the noise level low and can easily perform water supply and wastewater treatment.
Another object of the present invention is to provide a U-shaped groove cutting device that can maintain the height and level of cutting positions of both side walls of the U-shaped groove at a predetermined level.

  According to the U-shaped groove cutting device of the present invention, the rail (3) along the longitudinal direction of the U-shaped groove (2) is mounted on the jack (4) capable of contacting the inner wall (21) of the U-shaped groove (2). And a pair of engaged portions (E) (wedge-shaped constrictions in the illustrated embodiment) that respectively engage with engaging portions (equal angle mountain steel 32 in the illustrated embodiment) on both sides of the rail (3). The disc-shaped cutting blade (61) for cutting the inner wall of the U-shaped groove (2) is provided by providing a guide roller (81), a stand (5) supported by a stand leg (85) at the top of the guide roller (81). ) Is disposed on the gantry (5) so as to be swingable in the horizontal direction, a cutting control mechanism (69) for rotationally driving the cutting blade (61) is provided, and the jack (4 ) Causes the rail (3) to run along the longitudinal direction of the U-shaped groove (2), and the rail (3) has a predetermined height and level. Accordingly, the cutting machine body (6) is reciprocated along the rail (3), and the disc-shaped cutting blade (61) is swung to move the U-shaped groove (in the forward path and the return path). The inner wall (21) of 2) is cut.

In carrying out the present invention, the center fixing part 41 and the expansion / contraction parts 42 and 42 that extend and contract in both the left and right directions having a pressing part that presses a predetermined position in the height direction of the inner side surface 21 of the U-shaped groove 2 from the center fixing part 41. It is preferable that the rail fixed to the jack constituted by is accommodated in the U-shaped groove 2.
In carrying out the present invention, the cutting control mechanism 69 uses the rotational speed measuring means 691 for measuring the rotational speed of the cutting blade driving motor 62, the slip frequency calculator 692 for determining the torque characteristics, and the frequency of the inverter 693. It is preferable to include a frequency calculator 694 to be determined and a voltage calculator 695 in which a V / f value at which the number of gap magnetic fluxes generated by the excitation inductance of the electric motor 62 is always constant is input in advance into the circuit.
In implementing the present invention, the frequency setting unit 696 that can set the frequency of the maximum speed according to the use conditions and can correspond to the appropriate peripheral speed of the cutting blade 61 with respect to the size of the cutting blade 61, and the rotational speed of the electric motor 62 described above. It is preferable to provide an adder 697 for adding the slip frequency calculated by the slip frequency calculator 692 to the motor rotation speed converted to the frequency.
Further, in the implementation of the present invention, the added value from the adder 697 and the maximum speed frequency set by the frequency setter 696 are input to the frequency calculator 694 and the voltage calculator 695, and the frequency calculator 694 It is preferable to have a reduction gear 63 that is driven at a high speed by a variable frequency inverter that uses a frequency command value and a voltage command value of the inverter 693 as a calculation output from the voltage calculator 695 and is connected to the motor 62.
In implementing the present invention, the cooling water supplied to the electric motor 62 preferably cools the cutting blade 61 via the cutting blade column 64 and the cutting blade shaft 65.

  Here, the cooling water for cooling the electric motor 62 for driving the cutting blade can be reused as the cooling water for the cutting blade 61 during cutting after the electric motor 62 is cooled.

  According to the present invention, the cutting machine main body 6 is rotatably attached to the tip of the cutting machine main body 6 by selecting any one of a plurality of cutting blades 61 having different sizes. Even when the inner width length of the U-shaped groove 2 and the thickness of the side wall are different by the cutting control mechanism 69 of the cutting machine body 6, the cutting blade 61 is only replaced without increasing the output of the cutter driving motor 62. Thus, the upper part 21u of the side wall of the U-shaped groove 2 can be completely cut.

Even when the inner width L of the U-shaped groove 2 is narrow and the side wall thickness T is too thick, by changing several types of cutting blades 61 in stages at the time of cutting, A continuous and complete cutting operation can be performed.
At that time, the frequency of the maximum speed corresponding to the cutting blade 61 is set for each cutting blade 61 of each diameter, and a current corresponding to the frequency is input to the inverter 693, and the rotational speed of the electric motor 62 is detected by the speed detection. The adder 697 adds the slip frequency detected by the calculator 691 and obtained by the slip frequency calculator 692 to the frequency which is a function of the speed, and the added value is passed through the voltage calculator 695 and the frequency calculator 694. Since the rotational speed of the electric motor 62 is controlled by feeding back to the inverter 693, the most efficient cutting is possible.

  Furthermore, since the motor 62 for driving the cutter adopts a water cooling system and is a sealed type with high speed rotation, the cooling water is used again as cooling water for the cutting blade 61 during cutting after the motor 62 is cooled. In addition to simplifying the water supply and wastewater facilities, the size of the power source required for water supply and drainage can be reduced and the noise level can be kept low, thus solving environmental problems. There is an effect that it can be compactly accommodated without taking up space in the narrow U-shaped groove.

  Further, the rail 3 is supported by a jack 4, and by adjusting the jack 4, the height and levelness of the cutting positions of the side walls 21 of the U-shaped groove 2 can be easily maintained at a predetermined level. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are a plan view and a front view, respectively, showing the configuration of the U-shaped groove cutting device according to the embodiment of the present invention.

1 and 2, the U-shaped groove cutting device denoted as a whole by reference numeral 1 is divided into a rail 3 arranged in a U-shaped groove 2 whose cross section is shown in FIG. A gantry 5 that is movable on the rail 3 while being combined, and a cutting machine body 6 that is installed on the gantry 5 and that partially cuts the upper part 21 inside the U-shaped groove 2 (21u; see FIG. 3); A cutting drive device 7 installed on the pedestal 5 and swinging the tip of the cutting machine body 6 left and right to form a cut in the upper part 21 of the U-shaped groove 2; It comprises a feed drive device 8 that moves the entire groove cutting device 1 along the rail 3.
In FIG. 3, symbol L indicates the inner width length, symbol 21 indicates the inner side portion, symbol 21u indicates the inner upper portion, and symbol T indicates the thickness of the side wall.

  As shown in FIG. 10, the rail 3 includes, for example, a square steel pipe 31 and a pair of equilateral angle steels 32 and 32 joined to both side surfaces 31a and 31a of the square steel pipe 31 by welding. In the illustrated example, the bottom surface of the square steel pipe 31 constituting the rail 3 is fixed to the upper surface of each central fixing portion 41 of a pair of jacks 4 (also shown in FIGS. 1 and 2).

  The jack 4 includes a center fixing portion 41, stretchable portions 42 and 42 that extend and contract in both the left and right directions from the center fixed portion 41, and pressing members 43 and 43 at both ends of the stretchable portions 42 and 42. By applying a force in the extension direction to 42, both the left and right pressing portions 43, 43 press a predetermined position in the height direction of the inner side surface 21 of the U-shaped groove 2, and the rail is fixed to the jack 4 and the jack 4. The position in the height direction of the inner side surface 21 of the 3 U-shaped groove 2 is determined.

  FIG. 4 is a detailed plan view of the cutting machine (hereinafter, the cutting machine is referred to as a cutter) 6. FIG. 5 is a side view of FIG. 4 and 5, the cutter body 6 includes a disc-shaped cutting blade 61 having a plurality of types of diameters that can be exchanged, a cutting blade driving motor 62 that rotationally drives the cutting blade 61, and a cutting blade driving device. A speed reducer 63 for reducing the rotational speed of the motor 62, one end connected to the speed reducer 63, a rotational direction changer 63C for converting the rotational direction of the speed reducer 63 to a right angle, and the other end of the rotational direction changer 63C And a cutting blade column 64 for receiving the cutting blade shaft 65, and the cutting blade 61 is attached to the tip of the cutting blade shaft 65.

  Therefore, when the cutting blade driving motor 62 is rotated, the rotation speed is reduced by the speed reducer 63, and the rotation direction converter 63C converts the rotation direction around the horizontal axis of the motor 62 into the rotation direction around the vertical axis. The rotational force is transmitted to the cutting blade shaft 65 arranged vertically.

  A water supply port 62a for supplying cooling water from a cooling water supply line (not shown) and a drain port 62b for discharging the cooling water after cooling of the motor 62 are formed in the body of the cutting blade driving motor 62, Further, the drain port 62b is connected to a water supply port 64a formed on the outer peripheral portion of the cutting blade column 64 by a cooling water line (for example, a hose) Lw, and the cooling water once cooled the motor 62 is again supplied to the cutting blade column 64 and The cutting blade 61 is cooled via the cutting blade shaft 65.

  A cutting blade cover pedestal 67 disposed at the tip of the gantry 5 (not shown in FIGS. 4 and 5; see FIG. 2) and below the cutting blade 61 is attached to the tip of the gantry 5, A cutting blade cover 68A is attached to the cutting blade cover pedestal 67 on the left side of the cutting blade column 64 by a bracket (not shown), and a cutting blade is mounted on the right side of the cutting blade column 64 in the drawing. The cover 68B is attached by a bracket (not shown).

  Further, the cutting blade cover 68A has a hinge 68h on the left end side in the drawing, and is configured such that the right end portion of the cover, that is, the cutting blade column 64 side is lifted upward and opened. On the other hand, the cutter cover 68B has a hinge (not shown) on the right end side shown in the figure, and is configured such that the left end, that is, the cutting blade column 64 side is lifted upward and opened. .

  On the left end side of the cutting blade cover 68A and the right end side of the cutter cover 68B, a drain port 68b for discharging the cooling water after cooling of the cutting blade with the cooling water is provided. The waste water after cooling is sucked from the drain ports 68b of the cutting blade covers 68A and 68B by a drain pump (not shown) and processed.

2 and 5, reference numeral 81 denotes a guide roller, and reference numeral 85 supports the guide roller 81, and stands on the gantry 5 and the cutting blade cover gantry 67 so that the gantry 5 and the cutting blade cover gantry 67 are provided. The pedestal legs which are engaged with the rail 3 so as to be movable along the rail 3 with the guide roller 81 are shown.
The form of engagement between the guide roller 81 and the rail 3 will be described later with reference to FIG.

Next, the cutting drive device 7 will be described with reference to FIG.
The cutting drive device 7 includes a swivel base 71 to which the rear end bottom 6Ba of the base 6B of the cutter body 6 is attached, a cutting motor 72, a speed reducer 73, and a mounting base that supports the swivel base 71 and the speed reducer 73. A stand 74 is provided. The mounting base 74 is fixed to the frame 5 with bolts B.

The swivel base 71 incorporates a swivel shaft and a bearing (not shown), and the rotation of the cutting motor 72 is transmitted to the swivel axis of the swivel 71 via the speed reducer 73 and connected to the cutter body. 6 and the cutting blade 61 attached to the tip of the cutter body 6 is turned to make a cut 21u on the inside 21 of the U-shaped groove 2.
Here, since the cutting blade 3 can turn (swing) about 180 degrees, both side surfaces 21 inside the U-shaped groove 2 can be cut, and the cutting limit of the cutting operation is limited by respective limit switches (not shown). It has a structure.

Next, the feed driving device 8 will be described with reference to FIGS.
The feed driving device 8 engages with the rail 3 and guides the stand 5 and the cutting blade cover stand 67 (not shown in FIGS. 7 to 10) along the rail 3, and a feed roller 81. And a reduction gear 83 that decelerates the rotational speed of the motor 82.

  The feed motor 82 and the speed reducer 83 are connected by known means, and the opposite side (output shaft side) of the speed reducer 83 to the feed motor 82 side is attached to the gantry 5 by known means.

  On the other hand, the guide roller 81 is rotatably supported at the tip of a pedestal leg 85 extending downward from the pedestal 5 and the cutting blade cover pedestal 67 (not shown in FIGS. 7 to 10). As shown in FIG. 10, in the profile of the guide roller 81, a part of the cylinder is constricted in a wedge shape, and the deepest portion of the constriction in the wedge shape engages with the triangular top of the equilateral mountain steel 32 of the guide rail 3. Are arranged as follows.

As shown in FIG. 9, a sprocket wheel 84 is attached to the tip of the output shaft 83S of the speed reducer 83 via a connecting member J. In the example shown, a drive chain (not shown) is engaged with the sprocket wheel 84. is doing.
Here, the traveling speed of the entire apparatus is switched by the switching device when disconnected and when disconnected, and is determined in consideration of the speed during movement.

Next, the cutting control mechanism 69 of the cutter body 6 will be described with reference to FIG.
The cutting control mechanism 69 includes a speed sensor 691 that measures the rotational speed of the cutting blade driving motor 62, a slip frequency calculator 692 that determines torque characteristics of the cutting blade driving motor 62, an inverter 693, and the inverter 693. A frequency calculator 694 for determining the frequency of the current, a voltage calculator 695 for calculating the voltage applied to the inverter 693, a frequency setter 696 for setting the frequency of the current / voltage input to the cutting control mechanism 69, and the slip frequency It comprises an adder 697 that adds the slip frequency calculated by the calculator 692 and the motor speed converted to the frequency.

  The voltage calculator 695 is previously input with a V / f value in the circuit of the calculator 695 so that the number of gap magnetic fluxes formed by the excitation inductance of the electric motor 62 is always constant.

  The cutting control mechanism 69 sets the frequency of the maximum speed corresponding to the diameter of the cutter 61 attached by the frequency setting unit 696 and the use condition, inputs the current of the frequency to the inverter 693, and rotates the electric motor 62. The speed is detected by the speed sensor 691, the slip frequency obtained by the slip frequency calculator 692 is added to the frequency which is a function of the speed by the adder 697, and the added value is processed by the voltage calculator 695 and the frequency calculator. The rotational speed of the electric motor 62 is controlled by feeding back to the inverter 693 via the device 694.

  Next, based on FIG. 12, the characteristics of the driving motor 62 of the cutter body 6 of the present embodiment and the conventional general-purpose cutter will be compared.

The solid characteristic lines A1 to A5 in FIG. 12 are the three-phase 200V of the inverter control in this embodiment, the rated current 17.5A of the inverter inlet is set, and the reducer 63 with the reduction ratio 1/5 is used. The load torque characteristic of the drive motor 62 is shown. According to these characteristic diagrams A1 to A5, even if the load torque changes, the rotational speed is always constant.
On the other hand, a characteristic curve B of the conventional general-purpose cutter indicated by a broken line shows a characteristic curve of the load torque with respect to the rotation speed when the peripheral speed of the cutting blade is 35 m / sec.
The alternate long and short dash line C indicates a curve connecting points indicating the value of the rated current (inverter inlet current) on the characteristic curve of the present embodiment.

  The peripheral speed of the conventional general-purpose cutter is usually 35 to 40 m / sec in concrete cutting, and the cutting efficiency is usually the best. As described above, even if the load torque changes in this embodiment, the cutting blade rotates. Since the number is always kept constant (that is, the peripheral speed is constant at 35 m / sec), the cutter body 6 of the present embodiment shows that cutting can be performed under the best conditions. In order to further increase the cutting speed of the cutter, the load torque may be increased as long as it is below the limit of the rated current.

  Next, a method of cutting the U-shaped groove full width will be described with reference to FIGS. 3 and 13 to 16 by taking the following two examples.

First, the cutting blade 61 is slightly smaller than the inner width length L (see FIG. 3) of the U-shaped groove 2, and the thickness T (see FIG. 3) of the side wall 21 is within the maximum cutting depth of the cutting blade in the table below. A first example of the case will be described. Generally, the maximum cutting depth of the cutting blade of a concrete cutter is as follows.
Cutting edge diameter Maximum cutting depth (W)
Ｍｍ mm
10 70
12 95
14 120
16 145
18 170
Therefore, when the cutting blade 61 can be inserted into the U-shaped groove 2, the cutting thickness can be completely cut at the maximum cutting depth for each cutting blade diameter.
However, for example, when the inner width L of the U-shaped groove 2 is 300 mm and the side wall thickness is 100 mm, only a cutting blade diameter of 10 mm can be used. In this case, the thickness T of the side wall that can be completely cut is shown in the above table. Therefore, the full width of the U-shaped groove, which is the technical scope of the present invention, cannot be cut.

Next, a second example will be described.
First, assuming that the inner width length L of the U-shaped groove 2 is 300 mm and the side wall thickness T is 170 mm, only a cutting blade diameter of 10 mm can be used, but by sequentially replacing the cutting blades with 14 mm and 18 mm, It can be completely cut without lowering the cutting ability.

  Next, an example of the cutting operation of the second example will be described with reference to FIGS. FIG. 13 shows the first step at the time of cutting, FIG. 13 shows the second step, FIG. 14 shows the third step, and FIG. 15 shows a situation diagram of the chipping (shaded area) work of (FIGS. 12 to 14), respectively. Show.

  As a specific example, the most efficient and specific cutting operation when the inner width L of the U-shaped groove is 300 mm and the side wall thickness T is 170 mm will be described.

  First, in the first step (FIG. 12), a 10 mm cutting blade 61 is mounted, the power is turned on, and the number of revolutions of the cutting blade drive motor 62 is set (for example, 2300 r / min in FIG. 9), and then cutting is performed. The blade driving motor 62 is activated to start cutting one side of the side wall 21 of the U-shaped groove 2. In this case, the cutting speed is adjusted so that the inverter inlet current is less than the rated value. When the maximum cutting depth (for example, 70 mm) is reached, the cutting drive automatically stops (limit switch operation).

Next, the feed driving device 8 is driven to cut a predetermined length (for example, 1 m) (in the direction of the arrow Y1). During this cutting, the inlet current is adjusted so as to be kept below the rating. Turn off the power after cutting.
Next, the opposite side wall 21 is also cut by the same operation (in the direction of arrow Y2).

  After the cuts on both sides are finished, the cutting blade 61 is returned to the central portion of the U-shaped groove 2, and then the concrete portion at the top of the cutting surface is inserted into a predetermined length (for example, 500 mm) so that the cutting blade 61 of 14 mm can enter. ) Is a hatch (hatched portion D1 in FIG. 16).

  Next, the same operation as 14 吋 (see FIG. 13) and 18 吋 (see FIG. 14) is performed (see FIGS. 13 to 15; up to arrows Y3 to Y6).

  When the final chipping operation (hatched portions D1 to D3 in FIG. 16) is finished, 18 mm is attached, and thereafter, the cutting operation can be continued while maintaining the current below the rated current (characteristic line in FIG. 12). A1).

  According to the U-shaped groove cutting device 1 of the embodiment as described above, the cutting operation when the inner width length L of the U-shaped groove 2 is narrow and the side wall thickness T is thicker than that is a cutting blade with a small diameter. By sequentially changing from 61 to a cutting blade 61 having a larger diameter, a continuous and effective cutting operation can be performed with the cutting blade having the maximum diameter thereafter.

  Furthermore, the cooling water for cooling the electric motor 62 for driving the cutter is used again as the cooling water for the cutting blade 61 during cutting after the electric motor 62 is cooled, so that the facilities for water supply and waste water can be simplified. In addition, the size of the power source required for water supply and drainage can be reduced, and the noise level can be kept low.

The top view which shows the structure of the Example U-shaped groove cutting device of this invention. The side view corresponding to FIG. Sectional drawing of a U-shaped groove. The front view of the top view of the cutting machine main body in embodiment of this invention. The side view corresponding to FIG. The side view of the incision drive device in the embodiment of the present invention. The top view of the feed drive device in the embodiment of the present invention. FIG. 8 is a cross-sectional view taken along the line AA in FIG. 7. FIG. 8 is a cross-sectional view taken along the line B-B in FIG. 7. CC sectional view of FIG. The block diagram which showed the structure of the cutting | disconnection control mechanism in embodiment of this invention. The characteristic view which compared the characteristic of the cutting machine main body in embodiment of this invention, and the general purpose cutter of a prior art. The figure in case the diameter of the cutting blade in the middle stage is 10 mm in cutting operation explanatory drawing of a present Example. The figure in case the diameter of the cutting blade in the middle stage is 14 mm in the cutting work explanatory drawing of a present Example. The figure in case the diameter of the cutting blade in the middle stage is 18 mm in the cutting operation explanatory drawing of a present Example. The figure which showed the diameter of the cutting blade in the final stage simultaneously with 10 to 18 mm in the explanatory drawing of the chiseling work of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... U-shaped groove cutting device 2 ... U-shaped groove 3 ... Rail 4 ... Jack 5 ... Mount 6 ... Cutting machine main body / cutter main body 7 ... Cutting drive device 8 ... Feeding drive device 61 ... Cutting blade 62 ... Motor for driving cutting blade / Motor for driving driving 63 ... Speed reducer 71 ... Turning table 72 ... Motor for cutting / Motor for cutting 73 ... reducer 81 ... guide roller 82 ... feed motor / feed motor 83 ... reducer 84 ... sprocket 85 ... pedestal leg 691 ... rotational speed measuring means / speed Sensor 692 ... slip frequency calculator 693 ... inverter 694 ... frequency calculator 695 ... voltage calculator 696 ... frequency setter 697 ... adder

Claims (6)

A rail (3) along the longitudinal direction of the U-shaped groove (2) is placed on a jack (4) that can come into contact with the inner wall (21) of the U-shaped groove (2). A pair of guide rollers (81) each having an engaged portion (E) that engages with the joint portion (32) is provided, and the pedestal (5) supported by the pedestal legs (85) on the upper portion of the guide roller (81) A cutting machine body (6) having a disc-shaped cutting blade (61) for cutting the inner wall of the U-shaped groove (2) is disposed on the gantry (5) so as to be swingable in the horizontal direction. 61) is provided with a cutting control mechanism (69) for rotationally driving the rail (3) along the longitudinal direction of the U-shaped groove (2) by the jack (4), and the rail (3) has a predetermined height. Then, it is stored and fixed in the U-shaped groove (2) with the horizontality, and the cutting machine body (6) is reciprocated along the rail (3). U-shaped groove cutting apparatus characterized by cutting the inner wall (21) of the forward path and the backward path in the U-shaped groove by swinging the Jo cutting blade (61) (2). A telescopic part that expands and contracts in both the left and right directions, including a central fixing part (41) and a pressing part that presses a predetermined position in the height direction of the inner side surface (21) of the U-shaped groove (2) from the central fixing part (41). 42. The U-shaped groove cutting device according to claim 1, wherein the rail fixed to the jack constituted by 42, 42) is accommodated in the U-shaped groove (2). The cutting control mechanism (69) includes a rotation speed measuring means (691) that measures the rotation speed of the cutting blade driving motor (62), a slip frequency calculator (692) that determines torque characteristics, and an inverter (693). A frequency calculator (694) for determining the frequency, and a voltage calculator (695) in which a V / f value at which the number of gap magnetic fluxes created by the excitation inductance of the electric motor (62) is always constant is previously input into the circuit. The U-shaped groove cutting device according to claim 1, comprising: A frequency setter (696) capable of setting the frequency of the maximum speed according to use conditions and corresponding to the appropriate peripheral speed of the cutting blade (61) with respect to the size of the cutting blade (61), and the rotational speed of the electric motor (62) The U-groove cutting device according to claim 1, further comprising an adder (697) for adding the slip frequency calculated by the slip frequency calculator (692) to the motor rotation speed converted to the frequency. apparatus. The added value from the adder (697) and the maximum speed frequency set by the frequency setter (696) are input to the frequency calculator (694) and the voltage calculator (695), and the frequency calculator (695) 694) and a speed reducer connected to the electric motor (62) driven at a high speed by a variable frequency inverter using the output from the voltage calculator (695) as a frequency command value and a voltage command value of the inverter (693). The U-shaped groove cutting device according to claim 1, further comprising: The U-shaped groove cutting according to claim 1, wherein the cooling water supplied to the electric motor (62) cools the cutting blade (61) via the cutting blade column (64) and the cutting blade shaft (65). apparatus.

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