WO2020171351A1 - Sluice opening/closing apparatus and method for manufacturing rack bar thereof - Google Patents

Abstract

Provided are a sluice opening/closing apparatus and a method for manufacturing a rack bar of the sluice opening/closing apparatus, the method comprising the steps of: manufacturing a pair of flat steel bars (31) having a plurality of grooves that are symmetrical to each other and aligned in a line; and manufacturing a plurality of round bars (32), further comprising the steps: of hot-working the pair of flat steel bars (31) by putting the pair of flat steel bars (31) into oil and heating same, so that the size of each groove of the pair of flat steel bars (31) and the size of each round bar (32) have an interference fit tolerance therebetween and the pair of flat steel bars (31) can be equally heated up to the inside thereof; and/or cold-working the plurality of round bars (32) by cooling the plurality of round bars (32) in a cooling atmosphere formed by the evaporation of liquefied gas, so that the plurality of round bars (32) can be equally heated up to the inside thereof, and further comprising a step of coupling the plurality of round bars (32) between the pair of flat steel bars (31) by restoring same to room temperature in a state in which both ends of each round bar (32) are fitted with a clearance between the two facing grooves (A) of the pair of flat steel bars (31).

Description

Hydrogate opening and closing device and its manufacturing method of rack bar

It relates to a sluice door opening and closing device and a method of manufacturing a rack bar thereof, and in particular, to a method of manufacturing a rack bar by combining a round bar with a flat steel, and to a sluice door opening and closing device to which the rack bar manufactured by the method is applied.

In general, sluice gates are installed in dams, seawalls, reservoirs, or rivers for various purposes, such as controlling water flow or preventing backflow. It is composed of a frame installed in the sluice space, a sluice plate that opens and closes the waterway along the frame, and a device for raising and lowering the sluice plate, and the elevating device is driven by meshing with the gear box and gear box installed on the top of the sluice plate. It consists of a handle. The sluice plate is raised and lowered by a rack bar, so that the sluice gate is opened and closed. The rack bar is moved up and down by meshing with the gear of the sluice opening and closing device, and the rack bar is manufactured in the form of a bar or a ladder with a protrusion so as to mesh with the gear of the sluice opening and closing device. The ladder-shaped rack bar is composed of a pair of flat steel and a plurality of round bars inserted therebetween, and conventionally, the flat steel and the round bar have been welded to prevent separation from each other.

As in the prior art, when the rack bar of the sluice door opening and closing device is manufactured by welding, the rack bar is locally heated to a very high temperature. Depending on the work propensity and skill of the welder, the local heating of the rack bar may proceed at an excessively high temperature or may be performed for an excessively long time.In this process, the local thermal deformation of the rack bar occurs, which causes the surface of the rack bar to become finely uneven. If the degree of such thermal deformation is severe, the rack bar may bend. If the surface of the rack bar is finely uneven or bent, the rack bar cannot be lifted smoothly, and the gears of the rack bar and the gear box are not perfectly meshed, and the gearbox of the sluice door opening and closing device may fail.

It is intended to provide a method for manufacturing a rack bar of a sluice door opening and closing device that can prevent failure of the sluice door opening and closing device while preventing the thermal deformation caused by welding during the manufacture of the rack bar. It is not limited to the above-described technical problem, and another technical problem may be derived from the following description.

In the rack bar manufacturing method of the sluice door opening and closing device according to the present invention, the rack bar manufacturing method of the sluice door opening and closing device comprises the steps of: manufacturing a pair of flat steels having a plurality of grooves symmetrical to each other and arranged in a row; Including the step of manufacturing a plurality of round bars, the size of each groove of the pair of flat steels and the size of each round bar have a tolerance of force fit between each other, and evenly heated to the inside of the pair of flat steels. Hot working the pair of flat steels by putting the pair of flat steels in oil and heating them; And cold working the plurality of round bars by cooling the plurality of round bars in a cooling atmosphere formed by evaporation of a liquefied gas so that the inside of the plurality of round bars can be evenly cooled. And, the step of coupling the plurality of round bars between the pair of flat bars in a manner of restoring to room temperature in a state in which both ends of each round bar are loosely fitted into two facing grooves of the pair of flat steels. can do.

The step of manufacturing the pair of flat steel is to prepare the pair of flat steel from the base material of stainless steel STS 304, and the step of manufacturing the plurality of round bars is to prepare the plurality of round bars from the base material of stainless steel STS 304, The size of each groove of the pair of flat steels is 0mm to +(

Has a tolerance of 0.372%)mm and the size of each round bar is +(

0.825%)mm to +(

As it has 1.1%) mm of, the size of each groove of the pair of flat steels and the size of each round bar may have a tolerance of forcibly fitting each other.

In the hot working step, by putting the pair of flat steels in oil of at least 180° C. and heating at least 180° C., the size of each groove is 0mm to 0mm to +(

0.372% of)mm tolerance from +(0.002768×D)mm to +((

0.372%)+(0.002768×D)}mm or more, the size of each groove of the pair of flat steels and the size of each round bar can be transformed into a loose fit tolerance. have.

In the cold working step, the plurality of round bars are cooled to at least -165° C. in a cooling atmosphere formed by evaporation of liquid nitrogen, so that the size of each round bar is +(

0.825%)mm to +(

1.1%)mm tolerance of {(

0.825%)-(0.002788×D)}mm to {(

1.1%)-(0.002788×D)}mm or less, the size of each groove of the pair of flat steels and the size of each round bar will be deformed into a loose fit tolerance. I can.

In the hot working step, by putting the pair of flat steel in oil of at least 100°C and heating it to at least 100°C, the size of each groove is 0mm to +(

0.372%)mm tolerance of +(0.001384×D)mm to ((

0.372%)+(0.001384×D)}mm or more, and the cold working step comprises cooling the plurality of round bars to a minimum of -70°C or less in a cooling atmosphere formed by evaporation of dry ice. +( of the size of 32)

0.825%)mm to +(

1.1% of) mm tolerance ((

0.825%)-(0.001382×D)}mm to (

1.1%)-(0.001382×D)}mm or less, the tolerance of the forced fit between the size of each groove of the pair of flat steels and the size of each round bar will be transformed into a loose fit tolerance. I can.

A sluice door opening and closing device according to another aspect of the present invention is a sluice door opening and closing device to which a rack bar manufactured by a rack bar manufacturing method is applied, comprising: a frame formed in a rectangular frame shape and vertically installed on a water channel; A sluice plate that is sandwiched between both sides of the frame to open and close the waterway while elevating and descending; A rack bar manufactured by the manufacturing method, wherein a lower end is connected to the sluice plate to lift the sluice plate; And a gearbox for converting a rotational motion of a handle or a rotational motion of a motor due to an attractive force into an elevating motion of a rack bar using a combination of a plurality of gears.

Hot working by heating a pair of flat steels in oil for a pair of flat steels and a plurality of round bars manufactured so that the size of each groove of a pair of flat steels and the size of each round bar have a tolerance of force fitting between them. Or, in a cooling atmosphere formed by evaporation of liquefied gas, a plurality of round bars are cold-worked, and both ends of each round bar are loosely fitted into two facing grooves of a pair of flat steels and restored to room temperature. It is possible to manufacture a solid rack bar without welding flat steel and round bars, so that thermal deformation (bending) of the rack bar caused by welding when manufacturing the rack bar can be prevented.

By simultaneously performing hot working on a pair of flat steel and cold working on a plurality of round bars, the heating temperature of the flat steel can be lowered and the cooling temperature of the round bars can be lowered, thereby significantly reducing the assembly time of the rack bar. When hot working for a pair of flat steel and cold working for a plurality of round bars are performed at the same time, very inexpensive dry ice can be used instead of liquid nitrogen to cool the plurality of round bars, which can significantly reduce the manufacturing cost of rack bars. have.

As in the prior art, when the rack bar of the sluice door opening and closing device is manufactured by welding, the rack bar is locally heated to a very high temperature. Depending on the work propensity and skill of the welder, the local heating of the rack bar may proceed at an excessively high temperature or may be performed for an excessively long time.In this process, the local thermal deformation of the rack bar occurs, which causes the surface of the rack bar to become finely uneven. If the degree of such thermal deformation is severe, the rack bar may bend. If the surface of the rack bar is slightly uneven or bent, the rack bar cannot be lifted smoothly and the gearbox of the sluice door opening and closing device may be damaged. The sluice door opening and closing device to which the rack bar manufactured according to the present invention is applied does not require such welding, so that the sluice door opening and closing can be made smoothly, and the gears of the rack bar and the sluice door opening and closing device are perfectly meshed, so that failure of the gear box can be prevented.

1 is a perspective view of a sluice door opening and closing device according to an embodiment of the present invention.

2 is a partially enlarged view of the sluice door opening and closing device shown in FIG. 1.

3 is a view showing a comparison between the rack bar 30 shown in FIGS. 1 and 2 and the conventional rack bar 30'.

4 is a structural diagram of a coupling structure between the flat steel 31 and the round bar 32 of the rack bar 30 shown in FIG. 2.

5 is a cross-sectional view of each component of the rack bar 30 shown in FIG. 2.

6 is a flowchart of a method of manufacturing a rack bar according to an embodiment of the present invention.

7 is a flowchart of a method of manufacturing a rack bar according to another embodiment of the present invention.

8 is a flowchart of a method of manufacturing a rack bar according to another embodiment of the present invention.

9 is a graph of Test Example 1 in which a pulling force is applied to the flat steel 31 and the round bar 32 of the rack bar 30 of the sluice door opening and closing device according to an embodiment of the present invention.

10 is a graph of Test Example 2 in which a pulling force is applied to the flat steel 31 and the round bar 32 of the rack bar 30 of the sluice door opening and closing device according to an embodiment of the present invention.

The present invention, in the best form, in a method for manufacturing a rack bar of a sluice door opening and closing device, the steps of manufacturing a pair of flat steel 31 having a plurality of grooves symmetrically arranged with each other; Including the step of manufacturing a plurality of round bars (32), the size of each groove of the pair of flat steel (31) and the size of each round bar (32) has a tolerance of force fit between each other, the pair of Hot working the pair of flat steels 31 by putting the pair of flat steels 31 in oil and heating them so that they can be evenly heated to the inside of the flat steels 31; And cold working the plurality of round bars 32 by cooling the plurality of round bars 32 in a cooling atmosphere formed by evaporation of the liquefied gas so that the inside of the plurality of round bars 32 can be evenly cooled. In a method of restoring to room temperature in a state in which at least one of the steps is further included, and both ends of each of the round bars 32 are loosely fitted into two facing grooves A of the pair of flat steels 31 It presents a method of manufacturing a rack bar of a sluice door opening/closing device further comprising the step of coupling the plurality of round bars 32 between the pair of flat steels 31.

In addition, the present invention in the best form, in the sluice door opening and closing device to which the manufactured rack bar 30 is applied, the frame 10 is formed in a rectangular frame shape and installed vertically on the water channel; A sluice plate 20 that is sandwiched between both sides of the frame 10 to open and close the waterway while elevating and descending; As a rack bar (30) manufactured by the manufacturing method of claim 1, the lower end is connected to the sluice plate (20) to lift the sluice plate (20); And a gearbox 40 for converting a rotational motion of a handle or a rotational motion of a motor by a manpower into a lifting motion of the rack bar 30 by using a combination of a plurality of gears.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment of the present invention to be described below not only allows the sluice gate to be opened and closed smoothly by manufacturing the rack bar in a way that the flat steel and the round bar are fitted and coupled without welding, thereby preventing thermal deformation caused by welding during the manufacture of the rack bar. It relates to a method for manufacturing a rack bar of a sluice door opening and closing device capable of preventing failure of a sluice door opening and closing device, and a sluice door opening and closing device to which a rack bar manufactured by the method is applied. Hereinafter, such a method and apparatus may be simply referred to as “rack bar manufacturing method” and “sluice door opening and closing device”.

1 is a perspective view of a sluice door opening and closing device according to an embodiment of the present invention, and FIG. 2 is a partial enlarged view of the sluice door opening and closing device shown in FIG. 1. 1 and 2, the sluice door opening and closing device according to the present embodiment includes a frame 10, a sluice plate 20, a rack bar 30, a gearbox 40, and a handle 50. Since the characteristics of the present invention are in the manufacturing method of the rack bar 30 as described below, a brief description will be given of a sluice door opening and closing device to which the rack bar 30 to be described below is applied.

Those of ordinary skill in the art to which this embodiment belongs can understand that the sluice door opening and closing device to which the rack bar 30 is applied may be implemented in various shapes and structures in addition to the shapes and structures shown in FIGS. 1 and 2. For example, a motor (not shown) may be added in addition to the handle 50 as a power source. The frame 10 is formed in a rectangular frame shape and is vertically installed on the water channel surface. Both sides of the frame 10 have the shape of "[" and "]" in cross-sections so that the sluice plate 20 is fitted thereto and can be vertically slid. The sluice plate 20 is sandwiched between both sides of the frame 10 and serves to open and close the waterway while ascending and descending. The rack bar 30 is a rack bar 30 manufactured by a manufacturing method to be described below, and its lower end is connected to the sluice plate 20 to lift the sluice plate 20. The rack bar 30 is raised and lowered by a gearbox 40 driven by a manpower or a motor power.

The gearbox 40 converts a rotational motion of a handle or a rotational motion of a motor by a manpower into a lifting motion of the rack bar 30 by using a combination of a plurality of gears. The handle 50 is a member that is rotated by the force of a person, and transmits power for raising and lowering the sluice plate 20 to the gearbox 40. When a motor is added in addition to the handle as a power source, the motor generates a torque for raising and lowering the sluice plate 20, and the generated torque is transmitted to the gearbox 50. That is, the motor transmits a torque of a preset size to the gearbox 50 to raise and lower the sluice plate 20. The motor and the handle 40 are connected in parallel to the gearbox 50, and the handle 40 does not rotate when the sluice opening and closing device is driven by the motor. Since this driving structure is not related to the features of the present embodiment, detailed descriptions are omitted.

3 is a view showing a comparison between the rack bar 30 shown in FIGS. 1 and 2 and the conventional rack bar 30'. 3A and 3B are perspective and side views illustrating the rack bar 30 shown in FIGS. 1 and 2. 3(c) and (d) are perspective and side views showing a conventional rack bar 30'. In (c) and (d) of Figure 3, in order to help understand the degree of bending deformation of the rack bar 30 and the conventional rack bar 30' shown in Figs. 1 and 2, the conventional rack bar 30' is somewhat It is shown exaggeratedly curved.

Referring to FIGS. 3A and 3B, the rack bar 30 is manufactured in the form of a bar or ladder having a plurality of protrusions so as to mesh with the gears of the gear box 40. The ladder-shaped rack bar 30 is composed of a pair of flat steels 31 arranged parallel to each other and a plurality of round bars 32 that are inserted and connected between the pair of flat steels 31.

According to the conventional rack bar manufacturing method, after fitting both ends of each round bar 32 into the opposite hole of a pair of flat steel 31, the gap between the hole of the pair of flat steel 31 and each round bar 32 is welded. In such a way, a plurality of round bars 32 were coupled between the pair of flat steels 31. In this way, when the rack bar 30 ′ of the sluice door opening and closing device is manufactured by welding, the rack bar 30 ′ is locally heated to a very high temperature. Depending on the work tendency and skill of the welder, the local heating of the rack bar 30 ′ may be performed at an excessively high temperature or may be performed for an excessively long time. In this process, the local thermal deformation of the rack bar 30 ′ occurs, and thus, the rack bar 30 The surface of') becomes finely uneven. When the degree of such thermal deformation is severe, as shown in (c) and (d) of FIG. 3, the rack bar 30 ′ may be bent enough to be confirmed with the naked eye. If the surface of the rack bar 30 ′ is finely uneven or bent, the rack bar 30 ′ cannot be lifted smoothly and the gear box 40 is broken.

4 is a structural diagram of a coupling structure between the flat steel 31 and the round bar 32 of the rack bar 30 shown in FIG. 2. 4A is an inner side view of the flat steel 31 of the rack bar 30 shown in FIG. 2. Figure 4 (b) is a front view showing the coupling structure of the flat steel 31 and the round bar 32 of the rack bar 30 shown in Figures 1 and 2, Figure 4 (c) is a conventional rack bar (30) It is a front view to show the coupling structure of the flat steel 31' of') and the round bar 32'. The material of the rack bar 30 to be described below may be rolled steel for general structure, carbon steel for machine structure, or stainless steel STS, among which stainless steel STS 304 is preferable as a high-strength corrosion-resistant material, and is specified as I will explain.

Referring to Figure 4 (a), in this embodiment, a plurality of circular grooves (A) are formed on the inner surface of each flat steel 31. Referring to Figure 4 (b), in this embodiment, the groove (A) of each flat steel (31) and each round bar (32) are processed at room temperature to a tight fit tolerance, and then hot-worked or cold-worked to loose fit. Make it a state. Subsequently, the pair of flat steels 31 are arranged so that the openings of the grooves A on both sides face each other, and both ends of each round bar 32 are placed in two facing grooves A of the pair of flat steels 31. After each insertion, a plurality of round bars 32 are inserted between the pair of flat steels 31 in a manner of restoring to room temperature while applying pressure with a press in a loosely fitted state.

The hot working of this embodiment is performed by putting a pair of flat steels 31 into oil and heating them so that the insides of the pair of flat steels 31 are evenly heated. Cold working is performed by cooling the plurality of round bars 32 in a cooling atmosphere formed by evaporation of the liquefied gas so that the inside of the plurality of round bars 32 can be evenly cooled. Such hot working and cold working may be performed simultaneously.

Referring to (c) of FIG. 4, in the related art, a groove A'having a shape penetrating each of the flat steels 31' is formed in each of the pair of flat steels 31'. In the state where each round bar 32' is inserted into the opposite groove A'of the pair of flat steels 31', the welding part (S) that is a gap between the hole of the pair of flat steels 31 and each round bar 32 ) By welding a plurality of round bars (32') between the pair of flat steel (31) was coupled. As described above, in the rack bar 30 ′ manufactured by such a conventional welding method, the surface of the rack bar 30 ′ is finely uneven or bent due to local thermal deformation. As a result, as the gears of the rack bar 30 and the gearbox 40 of the sluice door opening and closing device are not perfectly engaged, the lifting and lowering of the rack bar 30' cannot be made smoothly, and an overload occurs in the gearbox 40, thereby causing a failure. Cause.

5 is a cross-sectional view of each component of the rack bar 30 of FIG. 2. Figure 5 (a) is a cross-sectional view of the flat steel 31 of the rack bar 30, Figure 5 (b) is a longitudinal cross-sectional view of the round bar 32 of the rack bar 30. Table 1 below lists the dimensions of the flat steel 31 and the round bar 32 of various standards. Here, “A” indicates the depth of the groove of the flat steel 31, “B” indicates the thickness of the flat steel 31, “H” indicates the width of the flat steel 31, and “L” indicates the round bar ( 32), and “D” indicates the standard dimensions of the diameter of the groove of the flat steel 31 and the diameter of the round bar 32. 5 shows a flat steel 31 and a round bar 32 corresponding to the D=16mm standard. Hereinafter, an embodiment of the D=16mm standard will be described. Those of ordinary skill in the art to which this embodiment belongs can understand that the following description may be applied to embodiments of other standards.

D	Pyeonggang (31)		Round bar (32)		A	B	H	L
	Minimum tolerance	Maximum tolerance	Minimum tolerance	Maximum tolerance
16	0.000	0.015	0.033	0.044	10	15	40	50
22	0.000	0.017	0.039	0.052	8	12	65	55
25	0.000	0.019	0.041	0.055	11	16	65	70
26	0.000	0.019	0.042	0.056	11	16	75	70
32	0.000	0.021	0.047	0.062	15	22	90	90
35	0.000	0.022	0.049	0.065	17	25	90	99
43	0.000	0.024	0.054	0.072	30	38	105	140
51	0.000	0.027	0.059	0.072	30	38	125	160
65	0.000	0.030	0.067	0.089	30	38	180	190

6 is a flowchart of a method of manufacturing a rack bar according to an embodiment of the present invention. Referring to Figure 6, the rack bar manufacturing method according to an embodiment of the present invention consists of the following steps. In step 110, a pair of flat steels 31 having a plurality of grooves arranged in a line are symmetrical to each other from the base material of stainless steel STS 304 by cutting or the like. In step 120, a plurality of round bars 32 are manufactured from the base material of stainless steel STS 304 using a cutting process or the like. Here, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 have a tolerance for force fitting. According to this embodiment, the pair of flat steels 31 in step 110 At the time of manufacture, the diameter of each groove (A) at room temperature 20 °C is 16mm to 16.015mm for the reference dimension (D) 16mm [{D+(

0.372%)}mm], and the depth of the groove (A) is formed to a depth of 10 mm when the thickness of each flat steel 31 is 15 mm, and the adjacent groove (A) on the inner surface of each flat steel 31 ) The spacing between them is formed equal to the spacing of the gear meshing with the rack bar. When manufacturing the round bar 32 in step 120, the diameter of each round bar 32 at room temperature of 20° C. is 16.033mm to 16.044mm for the standard size 16mm [{D+(

0.825%)}mm to {D+(

1.1%)}mm], and the length of the round bar 32 is formed to be 50mm.

In this way, the size of each groove of the pair of flat steel 31 is 0mm to +0.015mm[+() at room temperature 20°C for the standard size of each groove of 16[D]mm.

0.372%)mm], and the size of each round bar (32) is +0.033mm to +0.044mm [+(

0.825%)mm to +(

1.1%) mm], the size of each groove of the pair of flat steels 31 and the size of each round bar 32 have a tolerance of forcibly fitting each other.

In step 130, the pair of flat steels 31 manufactured in step 110 are hot-processed by putting a pair of flat steels 31 in oil and heating them so that the inside of the pair of flat steels 31 can be evenly heated. . Examples of oils used in such hot processing include fatty oils, mixed oils, and mineral oils. Depending on the temperature of the oil so that the pair of flat steels 31 can be heated to the inside, wait for 10 minutes to 1 hour in the state of being completely immersed in the oil, and then take it out. The amount of elongation during hot working of each flat steel 31 is as shown in FIG. 5. When each flat steel 31 is manufactured, the coefficient of thermal expansion of stainless steel STS 304 is 17.3×10 ^-6 m/(m) at 0°C or higher. ℃), so it can be calculated by the following equation (1).

[Equation 1]

Thermal expansion amount = length × coefficient of thermal expansion × temperature change

When each flat steel 31 is manufactured at room temperature at 20℃ and then heated to 180℃ in hot working, the amount of thermal expansion = 16mm×17.3×10 ^-6 ×160= 0.044mm [Dmm×17.3×10 ^-6 ×160 = ( 0.002768×D)mm], the diameter of the groove A of the flat steel increases by 0.044mm [(0.002768×D)mm]. That is, the tolerance of each groove diameter of the flat steel 31 heated at 180°C is +0.044mm to +0.059mm [+(0.002768×D)mm to +{(

0.372%)+(0.002768×D)}mm], and the diameter tolerance of each round bar 32 at room temperature of 20℃ is +0.033mm to +0.044mm [+(

0.825%)mm to +(

1.1%)mm], so the minimum clearance between each groove of the pair of flat steel 31 and the round bar 32 is 0.0000mm, and the maximum clearance is 0.026mm, which is a loose fit tolerance. Accordingly, insertion of both ends of the round bar 32 into the facing groove of the pair of flat steels 110 can be made very easily. As such, in step 130, by putting the pair of flat steels 31 in oil of at least 180°C and heating them to at least 180°C, the size of each groove is 0mm to +0.015mm[+(

0.372%)mm] tolerance of +0.044mm to +0.059mm [+(0.002768×D)mm to +{(

Of 0.372%)+(0.002768×D)}mm ], the tolerance of force fit between the size of each groove of the pair of flat steels (31) and the size of each round bar (32) is loose fit Transformed into tolerance.

In step 140, pressure is applied with a press while both sides of each round bar (32) manufactured in step 120 are loosely fitted into the two grooves (A) facing each other of the pair of flat steels (31) hot-machined in step 130. The plurality of round bars 32 are coupled between the pair of flat steels 31 while leaving them in an environment at room temperature of 20°C. Here, the pressure of the press is a pair of flat steels 31 and a pair of flat steels 31 in the room temperature restoration process as the room temperature restoration process takes a considerable amount of time in a state in which a plurality of round bars 32 are loosely fitted between the pair of flat steels 31 It is used to prevent the assembly shape between the plurality of round bars 32 from being distorted.

As described above, when the pair of flat steels 31 is heated to 180°C and returns to room temperature 20°C, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 are loosely fitted. The tolerance of the force-fitting is restored to the tolerance. The diameter of each groove of the pair of flat steel 31 is less than 16mm[Dmm], and the diameter of each round bar 32 is 16.044mm[{D+(

If it exceeds 1.1%)}mm], cracks may occur around the grooves of the flat steels 31 as the diameter of each round bar 32 is too large than the diameters of each groove of the pair of flat steels 31. The diameter of each groove of the pair of flat steel 31 is 16.015mm [{D+(

0.372%)}mm] and the diameter of each round bar 32 is 16.033mm[{D+(

If it is less than 0.825%)}mm], the surface of each round bar 32 cannot be firmly pressed into the inner surface of each groove of a pair of flat steels 31, so a pair of flat steels ( The round bar 32 can be easily separated from 31).

Room temperature 20 ℃ above is only an example of the environmental temperature in which the rack bar 30 of the present embodiment is used, and the environmental temperature is within the range of -40 ℃ to 40 ℃, a pair of the same numerical value as the example shown in FIG. When the flat steel 31 and the plurality of round bars 32 are manufactured, there is no cracking around the groove of the flat steel 31, and the surface of each round bar 32 is hard on the inner surface of each groove of the pair of flat steel 31 Can be squeezed together.

7 is a flowchart of a method of manufacturing a rack bar according to another embodiment of the present invention. Referring to FIG. 7, the method of manufacturing a rack bar according to the embodiment illustrated in FIG. 7 includes the following steps. In step 210, a pair of flat steels 31 having a plurality of grooves arranged in a row are symmetrical to each other from the base material of stainless steel STS 304 by cutting or the like. In step 220, a plurality of round bars 32 are manufactured from the base material of stainless steel STS 304 using a cutting process or the like. Here, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 have a tolerance of force fitting. In steps 210 and 220, a pair of flat steels 31 and a plurality of round bars 32 are manufactured in the same size as the example shown in FIG. 5 as in the embodiment shown in FIG. 6. Therefore, a detailed description of this will be replaced with the above description with respect to FIG. 5.

In step 230, the plurality of round bars 32 manufactured in step 220 are cooled in a cooling atmosphere formed by evaporation of liquid nitrogen so that the inside of the plurality of round bars 32 can be evenly cooled. Cold work. The shrinkage during cold working of each round bar 32 is as shown in FIG. 7. When each flat steel 31 is manufactured, the coefficient of thermal expansion of stainless steel STS 304 is 17.3×10 ^-6 m/(m) at 0°C or higher. ℃), and the coefficient of thermal expansion of 0°C to -73°C is 14.8×10 ^-6 m/(m°C), so it can be calculated by Equation 1 as follows.

When each round bar 32 is manufactured at room temperature of 20°C and then cooled to -165°C in cold working, the amount of thermal expansion of 20°C to 0°C =16mm×17.3×10 ^-6 ×(-20) = -0.006mm [ Dmm×17.3×10 ^-6 ×(-20)=-(0.000346×D)mm], and the amount of thermal expansion of 0℃ to -165℃ =16mm×14.8×10 ^-6 ×(-165) = -0.039mm [ Since Dmm×14.8×10 ^-6 ×(-165)=-(0.002442×D)mm], the diameter of each round bar 32 decreases by 0.045mm [(0.002788×D)mm]. That is, the diameter tolerance of the round bar 32 in the -165°C cooling state is -0.012mm to -0.001mm [{(

0.825%)-(0.002788×D)}mm to {(

1.1%)-(0.002788×D)}mm], and the tolerance of each groove diameter of the flat steel 31 at room temperature of 20℃ is 0mm to +0.015mm[+(

0.372%) mm], so the minimum clearance between each groove of the pair of flat steels 31 and the round bar 32 is 0.001mm, and the maximum clearance is 0.027mm, which is a loose fit tolerance. Accordingly, insertion of both ends of the round bar 32 into the facing groove of the pair of flat steels 110 can be made very easily. As such, in step 230, the plurality of round bars 32 are cooled to at least -165° C. in a cooling atmosphere formed by evaporation of liquid nitrogen, so that the size of each round bar 32 is +0.033mm to +0.044mm [+(

0.825%)mm to +(

1.1%)mm] tolerance of -0.012mm to -0.001mm [{(

0.825%)-(0.002788×D)}mm to {(

1.1%)-(0.002788×D)}mm] or less, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 Deformed to fit tolerance.

In step 240, pressure is applied with a press while loosely fitting both sides of each round bar (32) cold-worked in step 230 into two grooves (A) facing each other of the pair of flat steels (31) manufactured in step 210. The plurality of round bars 32 are coupled between the pair of flat steels 31 while leaving them in an environment at room temperature of 20°C. Here, the pressure of the press is a pair of flat steels 31 and a pair of flat steels 31 in the room temperature restoration process as the room temperature restoration process takes a considerable amount of time in a state in which a plurality of round bars 32 are loosely fitted between the pair of flat steels 31 It is used to prevent the assembly shape between the plurality of round bars 32 from being distorted.

As described above, when the plurality of round bars 32 are cooled to -165°C and return to room temperature 20°C, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 are loosely fitted. The tolerance of the force-fitting is restored to the tolerance. The diameter of each groove of the pair of flat steel 31 is less than 16mm[Dmm], and the diameter of each round bar 32 is 16.044mm[{D+(

If it exceeds 1.1%)}mm], cracks may occur around the grooves of the flat steels 31 as the diameter of each round bar 32 is too large than the diameters of each groove of the pair of flat steels 31. The diameter of each groove of the pair of flat steel 31 is 16.015mm [{D+(

0.372%)}mm] and the diameter of each round bar 32 is 16.033mm[{D+(

If it is less than 0.825%)}mm], the surface of each round bar 32 cannot be firmly pressed into the inner surface of each groove of the pair of flat steel 31, and thus a pair of flat steel ( The round bar 32 can be easily separated from 31).

8 is a flowchart of a method for manufacturing a rack bar according to another embodiment of the present invention. Referring to FIG. 8, the method of manufacturing a rack bar according to the embodiment illustrated in FIG. 8 consists of the following steps. In step 310, a pair of flat steels 31 having a plurality of grooves arranged in a row are symmetrical to each other from the base material of stainless steel STS 304 by cutting or the like. In step 320, a plurality of round bars 32 are manufactured from the base material of stainless steel STS 304 using a cutting process or the like. Here, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 have a tolerance of force fitting. In steps 310 and 320, the pair of flat steels 31 and the plurality of round bars 32 are manufactured in the same size as the example shown in FIG. 5 as in the embodiment shown in FIG. 5. Therefore, a detailed description of this will be replaced with the above description with respect to FIG. 5.

In step 330, the pair of flat steels 31 manufactured in step 310 are hot-processed by putting a pair of flat steels 31 in oil and heating them so that the inside of the pair of flat steels 31 is evenly heated. . When each flat steel 31 is manufactured at room temperature of 20℃ and then heated to 100℃ in hot working, the amount of thermal expansion = 16mm×17.3×10 ^-6 ×80 = 0.022mm [(0.001384×D)mm] The diameter of the groove (A) increases by 0.022 mm. That is, the tolerance of each groove diameter of the flat steel 31 heated at 100°C is +0.022mm to +0.037mm [+(0.001384×D)mm to +{(

0.372%) + (0.001384 × D)} mm].

In step 340, the plurality of round bars 32 manufactured in step 320 are cooled in a cooling atmosphere formed by evaporation of dry ice so that the inside of the plurality of round bars 32 can be evenly cooled. Cold work. When each round bar 32 is manufactured at room temperature of 20°C and then cooled to -70°C in cold working, the amount of thermal expansion of 20°C to 0°C =16mm×17.3×10 ^-6 ×(-20) = -0.006mm [ Dmm×17.3×10 ^-6 ×(-20)=-(0.000346×D)mm], and the amount of thermal expansion between 0℃ and -70℃ =16mm×14.8×10 ^-6 ×(-70) = -0.017 mm [ Since Dmm×14.8×10 ^-6 ×(-70)=-(0.001036×D)mm], the diameter of each round bar 32 decreases by 0.022mm (reflecting rounded value)[(0.001382×D)mm] . That is, the diameter tolerance of the round bar 32 in the -70°C cooling state is 0.011mm to +0.022mm [{(

0.825%)-(0.001382×D)}mm to {(

1.1%)-(0.001382×D)}mm].

Each groove diameter tolerance of the flat steel 31 heated at 100°C by hot working in step 330 is +0.022mm to +0.037mm [+(0.001384×D)mm to +{(

0.372%)+(0.001384×D)}mm], and the diameter tolerance of the round bar 32 in the -70°C cooled state by cold working in step 440 is 0.011mm to +0.022mm [{(

0.825%)-(0.001382×D)}mm to {(

1.1%)-(0.001382×D)}mm], so the minimum clearance between each groove of the pair of flat steels 31 and the round bar 32 is 0.000mm, and the maximum clearance is 0.026mm, which is a loose fit tolerance. . Accordingly, insertion of both ends of the round bar 32 into the facing groove of the pair of flat steel 31 can be made very easily.

As such, in step 330, the pair of flat steels 31 are put in oil of at least 100°C and heated to at least 100°C, so that the size of each groove is 0mm to +0.015mm[+(

0.372%)mm] tolerance of +0.022mm to +0.037mm [+(0.001384×D)mm to +{(

0.372%) + (0.001384 × D)} mm] or more of the tolerance, and in step 340, the plurality of round bars 32 are cooled to at least -70°C in a cooling atmosphere formed by evaporation of dry ice. 32) of the size of +0.033mm to +0.044mm [+(

0.825%)mm to +(

1.1%)mm] tolerance of 0.011mm to +0.022mm [{(

0.825%)-(0.001382×D)}mm to {(

1.1%)-(0.001382×D)}mm] of each groove of the pair of flat steels 31 and the size of each round bar 32. Deformed to fit tolerance.

In step 350, the two sides of each round bar 32 cold-worked in step 340 are loosely fitted into two grooves (A) facing each other of the pair of flat steels 31 hot-worked in step 330, and pressure is applied with a press. A plurality of round bars 32 are coupled between the pair of flat steels 31 in a manner that is allowed to stand in an environment at room temperature of 20° C. Here, the pressure of the press is a pair of flat steels 31 and a pair of flat steels 31 in the room temperature restoration process as the room temperature restoration process takes a considerable amount of time in a state in which a plurality of round bars 32 are loosely fitted between the pair of flat steels 31 It is used to prevent the assembly shape between the plurality of round bars 32 from being distorted.

As described above, when the pair of flat steels 31 are heated to 100°C and the plurality of round bars 32 are cooled to -70°C and then returned to room temperature of 20°C, the size of each groove of the pair of flat steels 31 And the tolerance of the loose fit between the size of each round bar 32 is restored to the forced fit tolerance. The diameter of each groove of the pair of flat steel 31 is less than 16mm [Dmm], and the diameter of each round bar 32 is 16.044mm [{D+(

If it exceeds 1.1%)}mm], cracks may occur around the grooves of the flat steels 31 as the diameter of each round bar 32 is too large than the diameters of each groove of the pair of flat steels 31. The diameter of each groove of the pair of flat steel 31 is 16.015mm [{D+(

0.372%)}mm] and the diameter of each round bar 32 is 16.033mm[{D+(

If it is less than 0.825%)}mm], the surface of each round bar 32 cannot be firmly pressed into the inner surface of each groove of the pair of flat steel 31, and thus a pair of flat steel ( The round bar 32 can be easily separated from 31).

In the embodiment shown in FIG. 8, the heating temperature of the flat steel 31 is lowered and the cooling temperature of the round bar 32 by simultaneously performing hot working on the pair of flat steels 31 and cold working on the plurality of round bars 32 It is possible to lower the assembly time of the rack bar 30 can be significantly reduced. Since the boiling point of nitrogen is -196°C and the boiling point of carbon dioxide is -78°C, dry ice cannot be used when only cold working is performed on the plurality of round bars 32. As described above, in the embodiment shown in FIG. 8, since very inexpensive dry ice can be used instead of liquid nitrogen for cooling the plurality of round bars 32, the manufacturing cost of the rack bar 30 can be significantly reduced.

In order to determine the possibility of damage in the process of using the rack bar 30 manufactured according to the embodiments shown in FIGS. 6, 7 and 8, a total of three examples and a total of four comparative examples were prepared, and then a pulling force tester was used. A pulling force test for each Example and Comparative Example was performed by applying a pulling force to the flat steel 31 and the round bar 32 of each Example and Comparative Example.

<Examples 1 to 3>

The diameter of each groove (A) of the flat steel 31 is 16.015 mm, the diameter of the round bar 32 is 16.033 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Example 1 was manufactured according to the manufacturing method shown in FIG. 6 by hot working the flat steel 31 at 180°C. As such, Example 1 is a case where the groove diameter of the flat steel 31 is processed to the maximum allowable dimension and the diameter of the round bar 32 is processed to the minimum allowable dimension.

The diameter of each groove (A) of the flat steel 31 is 16.008 mm, the diameter of the round bar 32 is 16.039 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Example 2 was manufactured according to the manufacturing method shown in FIG. 7 in a manner of cold working the round bar 32 at -165°C. As described above, Example 2 is a case in which the diameter of the groove of the flat steel 31 and the diameter of the round bar 32 are processed to an intermediate value between the maximum and minimum allowable dimensions.

The diameter of each groove (A) of the flat steel 31 is 16.000 mm, the diameter of the round bar 32 is 16.044 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), Example 3 was manufactured according to the manufacturing method shown in FIG. 8 by hot working the flat steel 31 at 100°C and cold working the round bar 32 at -70°C. As such, Example 3 is a case where the groove diameter of the flat steel 31 is processed to the minimum allowable dimension, and the diameter of the round bar 32 is processed to the maximum allowable dimension.

<Comparative Examples 1-4>

The diameter of each groove (A) of the flat steel 31 is 16.024 mm, the diameter of the round bar 32 is 16.024 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Comparative Example 1 was manufactured according to the manufacturing method shown in FIG. 6 by hot working the flat steel 31 at 180°C. As described above, Comparative Example 1 is a case where the flaw diameter of the flat steel 31 is processed larger than the maximum allowable dimension, and the diameter of the round bar 32 is processed smaller than the minimum allowable dimension.

The diameter of each groove (A) of the flat steel 31 is 16.020 mm, the diameter of the round bar 32 is 16.028 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Comparative Example 2 was manufactured according to the manufacturing method shown in FIG. 7 by cold working the round bar 32 at -165°C. As described above, Comparative Example 2 is a case where the flaw diameter of the flat steel 31 is processed larger than the maximum allowable dimension, and the diameter of the round bar 32 is processed smaller than the minimum allowable dimension.

The diameter of each groove (A) of the flat steel 31 is 15.985 mm, the diameter of the round bar 32 is 16.059 mm, and the remaining dimensions are the same as the example shown in FIG. 5, so that the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Comparative Example 3 was manufactured according to the manufacturing method shown in FIG. 6 by hot working the flat steel 31 at 180°C. As described above, Comparative Example 3 is a case where the groove diameter of the flat steel 31 is processed smaller than the minimum allowable dimension, and the diameter of the round bar 32 is processed larger than the maximum allowable dimension.

The diameter of each groove (A) of the flat steel 31 is 15.970 mm, the diameter of the round bar 32 is 16.074 mm, and the remaining dimensions are the same as the example shown in FIG. 5, and the flat steel 31 and the round bar ( After manufacturing 32), the rack bar of Comparative Example 4 was manufactured according to the manufacturing method shown in FIG. 7 by cold working the round bar 32 at -120°C. As described above, Comparative Example 4 is a case where the groove diameter of the flat steel 31 is processed smaller than the minimum allowable dimension, and the diameter of the round bar 32 is processed larger than the maximum allowable dimension.

<Test Example 1>

For each of Examples 1 to 3 and Comparative Examples 1 to 4, the flat steel 31 and the round bar 32 were combined by applying a pulling force in the opposite direction to the direction in which the flat steel 31 and the round bar 32 were combined using a pulling force tester. The pulling force was measured when the round bar 32 deviated 1mm from the flat steel 31 based on the position. The experimental results are shown in Table 2 below.

division	Groove diameter of flat steel (31) (mm)	Diameter of round bar (32) (mm)	Pulling force (N)
Comparative Example 1	16.024	16.024	49
Comparative Example 2	16.020	16.028	137
Example 1	16.015	16.033	1825
Example 2	16.008	16.039	1901
Example 3	16.000	16.044	2087
Comparative Example 3	15.985	16.059	1780
Comparative Example 4	15.970	16.074	1610

From Table 2, it can be seen that Examples 1 to 3 have higher pulling force than Comparative Examples 1 to 4. In Comparative Examples 1 and 2, it can be seen that the diameter of the round bar 32 is too small than the groove diameter of the flat steel 31 compared to Examples 1 to 3, so that the pulling force of the rack bar 30 is very low. When Comparative Example 1 and Comparative Example 2 are applied to the sluice door opening and closing device, it can be seen that the round bar 32 can be easily separated from the pair of flat steels 31 in the process of using the sluice opening and closing device. In Example 4, it can be seen that the pulling force of the rack bar 30 is relatively low, although the diameter of the round bar 32 is larger than the groove diameter of the flat steel 31 compared to Examples 1 to 3. In order to find the cause, as a result of examining the groove portions of Comparative Example 3 and Comparative Example 4, it could be seen that a crack occurred in the groove portions of Comparative Examples 3 and 4. In particular, as the cracks that were wider in Comparative Example 4 than in Comparative Example 3 appeared, the pulling force of Comparative Example 4 was measured to be lower than that of Comparative Example 3. When Comparative Examples 3 and 4 are applied to the sluice door opening and closing device, the cracks in the grooves of Comparative Examples 3 and 4 in the process of using the sluice door opening and closing device become more and more severe, and the round bar 32 from the pair of flat steels 31 ) Can be easily separated.

9 is a graph of Test Example 1 in which a pulling force is applied to the flat steel 31 and the round bar 32 of the rack bar 30 of the sluice door opening and closing device according to an embodiment of the present invention. According to the graph shown in FIG. 9, Examples 1 to 3 and Comparative Examples 1 to 4 are arranged on the X-axis in the order in which the groove diameter of the flat steel 31 is gradually decreased and the diameter of the round bar 32 is gradually increased. The results of the pulling force test shown in Table 2 are shown on the Y-axis. Referring to FIG. 9, when the groove diameter of the flat steel 31 and the standard diameter of the round bar 32 are 16 mm, the groove diameter of the flat steel 31 is 0.000 mm to +0.015 mm, and the diameter of the round bar 32 is +0.033. It was found that when the rack bar 30 was manufactured according to the manufacturing method shown in FIGS. 6, 7 and 8 by processing with an interference fit tolerance of mm to +0.044 mm, it was possible to manufacture a solid rack bar 30 having very excellent pulling force. I can.

<Test Example 2>

In addition to the D=16mm standard of Test Example 1, the standard dimensions of the flat steel 31 and the round bar 32 were additionally determined for D=65mm and 65mm according to Table 1 and Table 3 below.Examples 4 to 6 and Comparative Examples 5 to 8 And, using a pulling force tester, the flat steel 31 and the round bar 32 are combined to apply a pulling force in the opposite direction to the flat steel 31 and the round bar 32. The pulling force was measured when it deviated from (31) by 1 mm. The experimental results are shown in Table 3 below.

division	Groove diameter of flat steel (31) (mm)	Diameter of round bar (32) (mm)	Pulling force (N)
Comparative Example 5	65.048	65.048	98
Comparative Example 6	65.040	65.056	278
Example 4	65.030	65.066	7570
Example 5	65.016	65.078	8094
Example 6	65.000	65.089	8466
Comparative Example 7	65.970	65.120	7866
Comparative Example 8	65.910	65.144	7512

10 is a graph of Test Example 2 in which a pulling force is applied to the flat steel 31 and the round bar 32 of the rack bar 30 of the sluice door opening and closing device according to an embodiment of the present invention. Referring to FIG. 10, it can be seen that Test Example 2 also shows the same results as Test Example 1. D=22mm, 25mm, 26mm, 32mm, 35mm, 43mm, 51mm The description of the test examples for the standards is omitted, but it can be seen that the same results as those of Test Examples 1 and 2.

So far, examples, comparative examples, and test examples for the present invention have been described. Although it has been described in detail through Examples, Comparative Examples and Test Examples of the present invention, this is not intended to limit the present invention, but only to prove the present invention. Those of ordinary skill in the art to which the present invention pertains will understand that the scope of the present invention is not limited by these examples, and the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. I will be able to. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the above description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (6)

1. In the rack bar manufacturing method of the sluice door opening and closing device,

   Manufacturing a pair of flat steels 31 symmetrical to each other and having a plurality of grooves arranged in a line;

   Including the step of manufacturing a plurality of round bars 32,

   The size of each groove of the pair of flat steels 31 and the size of each round bar 32 have a tolerance of force fitting,

   Hot working the pair of flat steels 31 by putting the pair of flat steels 31 into oil and heating them so that the insides of the pair of flat steels 31 are evenly heated; And

   Cold working the plurality of round bars 32 by cooling the plurality of round bars 32 in a cooling atmosphere formed by evaporation of liquefied gas so that the inside of the plurality of round bars 32 can be evenly cooled. Further comprising at least one step of,

   Between the pair of flat steels 31 in a manner that restores to room temperature in a state where both ends of each round bar 32 are loosely fitted into the two opposite grooves A of the pair of flat steels 31, the Rack bar manufacturing method of a sluice door opening and closing device further comprising the step of combining a plurality of round bars (32).
2. The method of claim 1,

   The step of manufacturing the pair of flat steel 31 is to prepare the pair of flat steel 31 from the base material of stainless steel STS 304,

   The step of manufacturing the plurality of round bars 32 is to manufacture the plurality of round bars 32 from the base material of stainless steel STS 304,

   The size of each groove of the pair of flat steels 31 is 0mm to +(

   

   Has a tolerance of 0.372%)mm, and the size of each round bar 32 is +(

   

   0.825%)mm to +(

   

   The rack bar of the sluice door opening/closing device, characterized in that the size of each groove of the pair of flat steels 31 and the size of each round bar 32 has a tolerance of forcibly fitting each other as it has 1.1%) mm of Manufacturing method.
3. The method of claim 2,

   In the step of hot working, the pair of flat steels 31 are placed in oil of at least 180° C. and heated to at least 180° C., so that the size of each groove is 0mm to 0mm to +(

   

   0.372% of)mm tolerance from +(0.002768×D)mm to +((

   

   0.372%)+(0.002768×D)}mm or more of the difference between the size of each groove of the pair of flat steels 31 and the size of each round bar 32 is a loose fit. Rack bar manufacturing method of a sluice door opening and closing device, characterized in that it is transformed into a fit tolerance.
4. The method of claim 2,

   In the cold working step, the plurality of round bars 32 are cooled to at least -165° C. in a cooling atmosphere formed by evaporation of liquid nitrogen, so that the size of each round bar 32 is +(

   

   0.825%)mm to +(

   

   1.1%)mm tolerance of {(

   

   0.825%)-(0.002788×D)}mm to {(

   

   1.1%)-(0.002788×D)}mm or less, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 Rack bar manufacturing method of a sluice door opening and closing device, characterized in that it is transformed into a fitting tolerance.
5. The method of claim 2,

   In the hot working step, the pair of flat steels 31 are put in oil of at least 100°C and heated to at least 100°C, so that the size of each groove is 0mm to +(

   

   0.372%)mm tolerance of +(0.001384×D)mm to ((

   

   0.372%) + (0.001384 × D)} mm or more to a tolerance,

   In the cold working step, the plurality of round bars 32 are cooled to at least -70°C or less in a cooling atmosphere formed by evaporation of dry ice, so that the size of each round bar 32 is +(

   

   0.825%)mm to +(

   

   1.1% of) mm tolerance ((

   

   0.825%)-(0.001382×D)}mm to (

   

   1.1%)-(0.001382×D)mm or less of the deformation, the size of each groove of the pair of flat steels 31 and the size of each round bar 32 are mutually forced fit tolerance. Rack bar manufacturing method of a sluice door opening and closing device, characterized in that it is transformed into a fit tolerance.
6. In the sluice door opening and closing device to which the rack bar 30 manufactured by the manufacturing method of claim 1 is applied,

   A frame 10 formed in a rectangular frame shape and vertically installed on the waterway surface;

   A sluice plate 20 that is sandwiched between both sides of the frame 10 to open and close the waterway while elevating and descending;

   As a rack bar (30) manufactured by the manufacturing method of claim 1, the lower end is connected to the sluice plate (20) to lift the sluice plate (20); And

   A sluice door opening and closing device comprising a gearbox (40) for converting a rotational motion of a handle or a rotational motion of a motor by a manpower into an elevating motion of the rack bar (30) using a combination of a plurality of gears.

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