Description

APPARATUS FOR MANUFACTURING OUTER RING FOR

COIL PROTECTION

Technical Field

[1] The present invention relates to an apparatus for manufacturing an outer ring to protect an outer circumference of both ends of a coil. More particularly, the present invention relates to an apparatus for manufacturing an outer ring for coil protection which is fitted into an outer circumference of a coil composed of a scrolled steel sheet with a predetermined length to safely protect the coil from damage caused by external physical impact or contamination, and can be safely and easily mass-produced and significantly improved in manufacturing efficiency.

[2]

Background Art

[3] In general, cold rolled steel sheet such as electrical steel sheet, automotive steel sheet or plated steel sheet is produced in a cold rolled process after undergoing several processes. The cold rolled steel sheet is surface-treated to come out as a finished product, and then scrolled into a coil to be transported and stored easily. The coil is manufactured in accordance with a set standard or a purchaser's request.

[4] The coil 300 manufactured in this fashion, as shown in FlG. 13, is fixed into an outer ring 200 at both ends thereof to be protected from physical impact-induced damage or contamination and transported safely. Also, the outer ring 200 is fastened to the coil 300 by a band material 400.

[5] Such an outer ring 200 is manufactured via a cutting device and a machining device. First, a steel sheet for the outer ring is cut by the cutting device to a length to suit an outer circumference of the coil. The cut steel sheet is bent in a circle to have a diameter corresponding to the length via the machining device so that it can be fitted into the outer circumference of the coil.

[6] However, conventionally to manufacture the outer ring 200, the steel sheet should be manually cut to a precise length corresponding to the outer circumference of the coil 300 which is varied in its dimensions. Furthermore, the intended number of coils 300 to be packaged should be individually cut off.

[7] As a result, this noticeably undermines efficiency in manufacturing the outer ring and potentially brings about industrial disaster such as safety-related accidents during the manual cutting of the steel sheet.

[8]

Disclosure of Invention

Technical Problem

[9] The present invention has been made to solve the foregoing problems of the prior art and it is therefore an object according to certain embodiments of the present invention is to provide an apparatus for manufacturing an outer ring which is fitted into an outer circumference of a coil to safely protect the coil from damage caused by external physical impact or contamination, and can be easily mass produced and significantly improved in manufacturing efficiency.

[10]

Technical Solution

[11] According to an aspect of the invention for realizing the object, there is provided an apparatus for manufacturing an outer ring to protect an outer circumference of a coil composed of a scrolled steel sheet, the apparatus including a supply for supplying a sheet for the outer ring in a predetermined direction; a cutting part for cutting the sheet transferred from the supply to a length to suit the outer circumference of the coil; a converting part for converting a horizontal transfer direction of the cut sheet at 90 degree into a vertical direction; a machining part for bending the transferred sheet into a right angle with respect to a width center thereof, pressurizing a horizontal surface of the bent sheet to bend into a circle and machining the circled sheet into the outer ring; and a controller for controlling operation of the supply, the cutting part, the converting part and the machining part.

[12] Preferably, the supply includes a rotating shaft for receiving a rotational driving force from a first motor to rotate in one direction; an uncoiler connected to an end of the rotating shaft and inserted into an inner circumference of the scrolled sheet coil; and a base having a bearing block disposed thereon to rotatably support the rotating shaft.

[13] More preferably, the uncoiler is divided into segments which are assembled together into a cylinder, wherein the segments are connected to an operation shaft via a plurality of links, and the operation shaft has an end connected to a load end of a first cylinder so as to expand or reduce the segments in a radial direction.

[14] More preferably, the uncoiler further includes a rotating arm having a lower end connected to a load end of a second cylinder to be rotatably assembled to the rotating shift; and a contact roll assembled on an upper end of the rotating arm to idly rotate in contact with an outer circumference of the sheet coil.

[15] Preferably, the cutting part includes a plurality of upper and lower feed rollers rotating in a direction to mesh with each other by a rotational driving force from a second motor; a guide roller for guiding the sheet to between the upper and lower feed rollers; and a cutter for cutting the sheet transferred horizontally between the upper and

lower feed rollers.

[16] More preferably, the lower feed rollers are connected to the second motor by a timing belt, and the upper feed rollers are assembled on the load end of the second cylinder positioned vertically to abut the lower feed rollers selectively and externally.

[17] More preferably, the cutter includes a knife fixed in position; and a third cylinder for operating a movable knife vertically so that the fixed and movable knives cross each other.

[18] More preferably, the apparatus further includes a detection roller abutting an outer surface of the sheet between the upper and lower feed rollers and the cutter; and an encoder disposed in a shaft of the detection roller to provide the number of rotations of the detection roller to the controller.

[19] Preferably, the converting part includes a plurality of conversion rollers disposed at a predetermined distance to be incrementally inclined from a horizontal direction to a vertical direction along a transfer direction of the sheet; a plurality of guide rollers for guiding the sheet converted from a horizontal direction to a vertical direction while passing the shift rollers; and a third motor for rotating the feed roller in abutment with the sheet in a predetermined direction.

[20] Preferably, the machining part includes first, second and third bending rollers for gradually bending the sheet into an 'L' shaped cross-section having horizontal and vertical surfaces; upper and lower machining gears abutting top and underside of the horizontal surface; and a fourth motor for providing a driving force to rotate the first, second and third rollers and the upper and lower machining gears.

[21] More preferably, each of the first and second bending rollers comprises a pair of roller members each having an outer surface abutting the sheet constructed of an inclined surface and a vertical surface.

[22] More preferably, the third bending roller comprises a pair of roller members each having an outer surface abutting the sheet constructed of a horizontal surface and a vertical surface.

[23] More preferably, each of the upper and lower machining gears comprises a pair of roller members disposed at a predetermined pitch vertically on the outer surface thereof abutting the horizontal surface of the sheet to mesh with each other.

[24] More preferably, the lower machining gear is connected to an upper end of an up- down shaft which moves vertically by a rotational driving force of a fifth motor so as to adjust a gap between the upper machining gear.

Brief Description of the Drawings

[25] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in

conjunction with the accompanying drawings, in which: [26] FlG. 1 is a plan view illustrating an apparatus for manufacturing an outer ring for coil protection according to the invention; [27] FlG. 2 is a front view illustrating an apparatus for manufacturing an outer ring for coil protection according to the invention; [28] FlG. 3 is an overall perspective view illustrating an apparatus for manufacturing an outer ring for coil protection according to the invention; [29] FlG. 4 is a configuration view illustrating a supply employed in an apparatus for manufacturing an outer ring for coil protection according to the invention; [30] FlG. 5 is a configuration view illustrating a cutting part employed in an apparatus for manufacturing an outer ring for coil protection according to the invention; [31] FlG. 6 is a plan view illustrating a converting part employed in an apparatus for manufacturing an outer ring for coil protection according to the invention; [32] FlG. 7 is a configuration view illustrating a machining part employed in an apparatus for manufacturing an outer ring for coil protection according to the invention;

[33] FlG. 8 is a cross-sectional view cut along the line A-A' of FlG. 7;

[34] FlG. 9 is a cross-sectional view cut along the line B-B' of FlG. 7;

[35] FlG. 10 is a cross-sectional view cut along the line C-C of FlG. 7;

[36] FlG. 11 is a cross-sectional view cut along the line D-D' of FlG. 7;

[37] FlG. 12 is a cross-sectional view illustrating an outer ring which is machined by upper and lower machining gears employed in an apparatus for manufacturing an outer ring for coil protection; and [38] FlG. 13 is a perspective view illustrating a coil whose outer circumference is fixed into an outer ring. [39]

Mode for the Invention [40] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. [41] FlG. 1 is a plan view illustrating an apparatus for manufacturing an outer ring for coil protection according to the invention. FlG. 2 is a front view illustrating an apparatus for manufacturing an outer ring for coil protection according to the invention. FlG. 3 is an overall perspective view illustrating an outer ring for coil protection according to the invention. [42] In the apparatus 100 of the invention, as shown in FlGs. 1 to 3, the outer ring 100 is fitted into an outer circumference of a coil composed of a scrolled steel sheet to protect the coil. Here, the outer ring 200 can be manufactured fast and safely to suit various

sizes of the outer circumference. The apparatus 100 includes a supply 10, a cutting part 20, a converting part 30, a machining part 40, and a controller 50.

[43] The supply 10 uncoils a sheet coil 2 composed of the steel sheet 1 scrolled to a predetermined length in one direction and supplies the sheet in one direction.

[44] As shown in FlGs. 1 to 4, the supply 10 includes a rotating shaft 12, an uncoiler 13 and a base 17. The rotating shaft 12 receives a rotational driving force from a first motor 11 to rotate in one direction. The uncoiler 13 is connected to an end of the rotating shaft 12 and inserted into an inner circumference 2a of the scrolled sheet coil 2. The base 17 has a bearing block 12a disposed thereon to rotatably support the rotating shaft 12.

[45] The uncoiler 13 is divided into segments 13a which are assembled together into a cylinder. The segments 13a are connected to an operation shaft 16 by a plurality of links 15. The operation shaft 16 has an end connected to a load end of a first cylinder 14 to expand or reduce the segments in a radial direction.

[46] Here, the operation shaft 16 is a shaft member which is back and forth movably assembled in an inner hole of the rotating shaft 12.

[47] Accordingly, with a first cylinder 14 set to move forth, the links 15 assembled to the operation shaft 16 are converted into a vertical direction so that an outer circumference of the uncoiler 13 is adjustable in accordance with an inner circumference of the sheet coil 2.

[48] The first motor 11 is connected to the rotating shaft 12 via a driving force delivery means 11a such as a chain, a belt and a sprocket.

[49] Also, the uncoiler 13 includes a rotating arm 18 and a contact roll 18a. The rotating arm is connected at a lower end to a load end of the second cylinder 19 to be rotatably assembled to the rotating shaft 19a. The contact roll 18a is assembled on an upper end of the rotating arm to idly rotate in contact with an outer circumference of the sheet coil 2.

[50] Accordingly, when the contact roll 18a disposed on the upper end of the rotating arm 18 abuts the outer circumference of the sheet coil 2, the sheet 1 is supplied in one direction more smoothly under constant tension force in uncoiling the sheet coil 2.

[51] As shown in FlGs. 1 to 3 and 5, the cutting part 20 cuts the sheet 1 which is uncoiled by the uncoiler 10 of the supply 10 and transferred in one direction. At this time, the sheet 1 is cut to a predetermined length to suit the outer circumference of the coil (reference sign 300 of FlG. 13).

[52] The cutting part 20 is constructed of a second motor 21, a plurality of upper and lower feed rollers 22a and 22b, a guide roller 23 and a cutter 24. The second motor generates a rotational driving force when a power voltage is applied. The upper and lower feed rollers 22a and 22b rotate in a direction to mesh with each other by a

rotational driving force of the second motor 21. The guide roller 23 guides the sheet 1 to between the upper and lower feed rollers 22a and 22b. The cutter 24 cuts the sheet 1 transferred horizontally between the upper and lower feed rollers 22a and 22b.

[53] The lower feed rollers 22b are connected to the second motor 21 by a timing belt

27. The upper feed rollers 22a are assembled on the load end of the second cylinder positioned vertically to abut the lower feed rollers 22b selectively and externally.

[54] Here, the upper and lower feed rollers 22a and 22b and the second cylinder 29 are located on a roller base 28 having the second motor 21 installed therein.

[55] The cutter 24 is constructed of a third cylinder 24c which operates a movable knife

24b vertically so that a knife 24a fixed in position at one side of the roller base 28 crosses the movable knife 24b.

[56] Furthermore, a detection roller 26b abuts an outer surface of the sheet 1 between the upper and lower feed rollers 22a and 22b and the cutter 24. An encoder 26 is disposed in a shaft of the detection roller to detect data on a transfer length of the sheet 1 and transmit the detected data to the controller.

[57] Also, an upper roller 26a and a cylinder 26b are provided above the detection roller

26b. The upper roller 26a rotates in a meshing direction with the detection roller 26b. The cylinder 26c drives the upper roller 26a reciprocally, that is, vertically up and down.

[58] Preferably, a guider 25 is located between the detection roller 26b and the cutter 24 to guide the sheet 1 transferred in one direction more smoothly toward the cutter 24.

[59] As shown in FIGs. 1 to 3 and 6, the converting part 30 converts a horizontal transfer direction of the cut sheet 1 at 90 degree into a vertical direction. Here as just described, the sheet 1 is cut to a predetermined length in accordance with the outer circumference of the coil (reference sign 300 of FIG. 13) by the cutter 24 of the cutting part 20.

[60] The converting part 30 includes a plurality of conversion rollers 33, a plurality of guide rollers 36 and a third motor 31. The conversion rollers 33 are disposed at a predetermined distance to be incrementally inclined from a horizontal direction to a vertical direction along a transfer direction of the sheet 1. The guide rollers 36 guide the sheet 1 converted from a horizontal direction to a vertical direction while passing the conversion rollers 30. The third motor 31 is positioned between the converting part and guide rollers 33 and 36 to rotate the feed rollers 32 in abutment with the sheet 1 in one direction.

[61] Here, the conversion rollers, guide rollers 36 and feed rollers 32 are rotatably assembled on another roller base 37. The conversion rollers 33 are rotatably supported at both ends thereof by a bearing block 33a disposed on the roller base 37. The guide rollers 36 and the feed rollers 32 are also rotatably supported by another bearing block (not illustrated) having a lower end disposed on a top surface of the roller base 37.

[62] Here, the guide rollers 36 are arranged along a curve to ensure the sheet transferred

1 to be converted into a vertical direction. But the invention is not limited thereto and optionally the guide rollers 33 may be positioned linearly.

[63] Moreover, an insert guide 44 is disposed at an exit side of the guide rollers 36 to guide the sheet converted to a vertical transfer direction toward the machining part 40 more securely.

[64] As shown in FlGs. 1 to 3 and 7, the machining part 49 bends the transferred sheet 1 into a right angle with respect to a width center thereof. Here, as described above, the sheet 1 transferred is converted from a horizontal direction to a vertical direction while passing the conversion rollers 33 of the converting part 30.

[65] At the same time, a horizontal surface (reference sign Ia of FlG. 12) of the bent sheet 1 is pressurized to be bent into a circle and the circled sheet is machined into the outer ring having a size corresponding to the outer circumference of the coil 300.

[66] The machining part 40 is constructed of first, second and third bending rollers 45,

45', 46, 46' and 47, 47', upper and lower machining gears 48 and 49 and a fourth motor 41. The first, second and third bending rollers 45, 45', 46, 46' and 47, 47' gradually bend the sheet 1 into an 'L' shaped cross-section having a horizontal surface Ia and a vertical surface Ib of FlG. 12. The upper and lower machining gears 48 and 49 abut top and underside of the horizontal surface Ia. The fourth motor 41 provides a driving force to rotate the first, second and third rollers 45, 45', 46, 46' and 47, 47' and the upper and lower machining gears 48 and 49.

[67] The first bending rollers 45 and 45' include an entrance guide 44a and a plurality of guide rollers 43 successively disposed at an entrance side thereof in a transfer direction of the sheet 1. The entrance guide 44a guides the sheet 1 converted into a vertical direction by the converting part 30 to be transferred in one direction. The third bending rollers 47 and 47' have an exit guide 44b disposed at an exit side to guide the sheet 1 bent at a right angle to be transferred in one direction.

[68] As shown in FlGs. 8 and 9, the first and second bending rollers 45, 45' and 46, 46' each are a pair of roller members which each have an outer surface abutting the sheet 1 constructed of an inclined surface 45a, 45a' and 46a, 46a' and a vertical surface 45b, 45b' and 46b, 46b'. Also, the first and second bending rollers 45, 45' and 46, 46' each are connected to an upper end of vertical roller shafts 45c, 45c' and 46c, 46c'.

[69] As shown in FlG. 10, the third bending rollers 47 and 47 are a pair of roller members which each have an outer surface abutting the sheet 1 constructed of a horizontal surface 47a and 47a' and a vertical surface 47b and 47b'. The third bending rollers 47, 47 are connected to an upper end of a vertical roller shaft 47c, 47c'.

[70] The upper and lower machining gears 48 and 49 each are gear members which are disposed at a predetermined pitch on the outer surface thereof abutting the horizontal

surface Ia of the sheet 1 to mesh with each other.

[71] Here, the first, second and third bending rollers 45, 45', 46, 46' and 47, 47' are disposed on the roller base 40a and each gear shaft 48a and 49b of the upper and lower machining gears 48 and 49 is rotatably supported by bearing blocks 48a and 49b located inside a gear base 40b.

[72] Each of the roller shafts 45c, 45c', 46c, 46c' and 47c, 47c' of the first, second and third bending rollers 45, 45',46, 46' and 47, 47' includes another gear member (not illustrated) meshed with a plurality of gear members 42a disposed in a mid length of a driven shaft 42. The driven shaft 42 is rotatably supported at both ends thereof inside the roller base 40a. The driven shaft 42 is connected to a driving shaft 41a of the fourth motor 41 by a driving force delivery means 42b such as a chain, a belt and a sprocket, which is joined at a mid length of the driven shaft 42.

[73] Another driven shaft 42c connected to the driving shaft 41a of the fourth motor 41 is connected to a gear shaft 48a of the upper machining gear 48 by a driving force delivery means 42d such as a chain, a belt and a sprocket.

[74] Accordingly, the upper machining gear 48 rotates with the first, second and third bending rollers 45, 45', 46, 46' and 47, 47' when the fourth motor 41 is driven.

[75] Also, as shown in FIG. 11, the lower machining gear 49 is connected to an up-down shaft 42' which moves vertically by a rotational driving force of a fifth motor 41' so as to adjust a gap between the upper machining gear 48.

[76] A driving gear disposed on a driving shaft of the fifth motor 41' is meshed with a driven gear 41a disposed on the up-down shaft 42'. The up-down shaft 42' is slidably and movably assembled on a bearing block 42c and a sleeve 42b' located inside the gear base 40b and screwed to an arm screw 42d'.

[77] An upper end of the up-down shaft 42 is rotatably assembled in a connecting hole

42a formed on a bearing block 49b of the lower machining gear 49 which is back and forth movably assembled on the gear base 40b.

[78] As a result, the fifth motor 41 when rotating in a direct or inverse direction, rotates the up-down shaft 42 screwed to the arm screw 42d in a direct and inverse direction to move the lower machining gear 49 vertically with respect to the upper machining gear 48, thereby adjusting a gap therebetween.

[79] Moreover, the upper and lower machining gears 48 have a collection box B at an exit side thereof. The collection box B collects and stores the outer ring 200 which is manufactured and dropped off after the sheet 1 is bent into a circle while passing between the upper and lower machining gears 48.

[80] The controller 50 controls rotational driving of the first motor 11 installed in the supply 10, back and forth movement of the first cylinder 14 which varies size of the outer circumference of the uncoiler 13, rotational driving of the second motor 21

installed in the converting part 20, and vertical movement of the second and third cylinders 24c and 29. Also, the controller 50 receives data detected by the encoder 26 to calculate a transfer length of the sheet, controls rotational driving of the third motor 31 disposed in the converting part and rotational driving of the fourth and fifth motors 41 and 41' of the machining part 40.

[81] The controller 50 includes an input button 51 for inputting a predetermined value for the size of the outer circumference 200 and a display window 52 for displaying the inputted value.

[82] As shown in FlGs. 12 and 13, in the apparatus 100 configured as above, an outer ring 200 is more effectively manufactured to be fitted into an outer circumference of a coil composed of a scrolled steel sheet. This safely protects the scrolled coil 300 from physical external impact or contamination during transportation thereof and prevents safety-related accidents. Also, the invention ensures automation through a continuous flow process, thereby producing the outer ring 200 with minimal manual work involved.

[83] That is, to manufacture the outer ring 200 in accordance with the dimension of the coil 300, the dimension is manually inputted through the input button 51 of the controller 50. Then, the first motor 11 rotates in one direction, starting the uncoiler 13 to rotate in an uncoiling direction.

[84] Here, the uncoiler 13 has a sheet coil 2 composed of a scrolled steel sheet 1 inserted thereinto. Thus, the sheet 1 is uncoiled slowly in one direction and the uncoiled sheet is guided to a guide roller 23 of the cutting part 20.

[85] Here, links 15 connected to each segment 13a of the uncoiler 13 are rendered foldable by a rotation shaft 12 moving horizontally by fluid pressure of the first cylinder 14. This easily adjusts the outer circumference dimension of the uncoiler 13 in accordance with an inner circumference dimension of the sheet coil 2.

[86] Therefore, the outer circumference dimension of the uncoiler 13 is properly adjusted in accordance with the inner circumference dimension of the sheet coil 13 piled on the uncoiler 13. This allows the uncoiler 13 to rotate integrally and intimately with the sheets, ensuring the sheet 1 to be supplied to the cutting part 20 more smoothly at a precise length.

[87] Furthermore, the driving motor 11 is driven automatically in response to a control signal of the controller 50. Thus, the uncoiler 13 can controllably perform uncoiling in correspondence with a value manually set through the controller 50, thereby supplying a predetermined length of the sheet.

[88] In addition, the uncoiler 13 includes a rotating arm 18 disposed at one side thereof to be rotated by a cylinder 19 and a contact roll 18a disposed on an upper end of the rotating arm 18 to abut an outer surface of the sheet 1. Therefore, the sheet can be

provided smoothly under a constant tension force when the sheet coil 200 is uncoiled and rotated.

[89] Subsequently, when a power voltage is applied to the second motor 21 of the cutting part 20, the upper and lower feed rollers 22a and 22b positioned successively from the guide roller 23 in a sheet transfer direction rotate in a direction to mesh with each other. This allows the sheet 1 entered between the upper and lower feed rollers 22a and 22b to move horizontally toward the cutter 24.

[90] Here, the cutter 24 is constructed of a detection roller 26b and an encoder 26. The detection roller 26b is disposed at an exit side of the cutter 24 to rotate in abutment with the sheet 1 transferred horizontally in one direction. The encoder 26 is disposed in a shaft of the detection roller 26b to sense, measure the transfer length and transmit the measured data to the controller 50.

[91] Accordingly, when the sheet 1 is transferred at the value set by the controller 50, the second motor 21 stops rotating in response to a control signal generated from the controller 50 to stall the sheet 1. At the same time, the second motor 21 activates the third cylinder 24c so that a movable knife 24b and a fixed knife 24a cross each other, thereby cutting the stalled sheet 1 at a length corresponding to the set value.

[92] Here, the sheet 1 is cut to have a size substantially equal to or greater than the outer circumference of the coil 300.

[93] Next, after the sheet 1 is cut by the cutter 24, the second motor 21 is set into motion again in response to the control signal to transfer the sheet 1 successively and cut it with the cutter 24.

[94] Then, the sheet 1 cut to a predetermined length by the cutting part 20 is conveyed to a converting part 30 and the sheet 1 entering the converting part 30 horizontally is converted into a vertical direction to be easily machined into a right angle cross- section.

[95] That is, the sheet transferred horizontally is converted into a vertical direction while passing the conversion rollers 33. Here the conversion rollers 33 are disposed at a predetermined distance to be incrementally inclined from a horizontal direction to a vertical direction. The sheet 1 converted into a vertical direction is transferred toward a machining part 40 vertically by the feed rollers 32 and the guide rollers 36 abutting the sheet 1 at both sides.

[96] Here, the converting part 30 is required to occupy a relatively great length so that the sheet 1 can be transferred in a vertical direction smoothly. Thus the converting part 30 may be curved or perpendicular in a small area but linear in a wide area.

[97] Afterwards, when the sheet 1 converted into a vertical direction enters the machining part 40, the sheet 1 is bent into a right angle cross-section having a horizontal surface Ia and a vertical surface Ib. The horizontal surface Ia bent is

machined into a circle to complete the outer ring 200.

[98] That is, the vertical sheet 1 passes through the entrance guide 44 and guide rollers

43 to the first bending rollers 45 and 45', second bending rollers 46, 46' and third bending rollers 47, 47'. Then, cross-section of the sheet 1 is bent into a right angle due to cross-sections of the rollers abutting the outer surface of the sheet 1, thereby machined to have the horizontal surface Ia and the vertical surface Ib. Also, with the horizontal surface Ia of the bent sheet 1 passing between the upper and lower machining gears 48 and 49, the horizontal surface Ia of the sheet 1 is bent into a circle due to the upper and lower machining gears 48 and 49 meshing with each other, thereby completing the outer ring 200.

[99] Here, the first, second and third bending rollers 45, 45', 46, 46' and 47, 47' and the upper machining gear 48 are driven by the fourth motor 41 which is simultaneously driven with the third motor 31 of the converting part 30. Thus, the sheet 1 is bent at a right angle and machined into a circle while transferred.

[100] Preferably, as shown in F1G.8, the first bending rollers 45, 45' primarily bend the sheet 1 at an angle of 30 degree. As shown in FlG. 9, the second bending rollers 46, 46' secondarily bend the sheet 1 at an angle of about 60 degree. Also, as shown in fig. 10, the third bending rollers 47, 47' bend the sheet 1 tertiarily at an angle of about 90 degree.

[101] Therefore, the sheet 1 passing through the machining part 40 is bent not once but step-wise through the first bending rollers 45, 45', second bending rollers 46, 46' and third bending rollers 47, 47'. This diminishes load of the sheet 1 resulting from bending, thereby assuring effective bending of the sheet 1.

[102] Here, a small gap between the upper machining gear 48 and the lower machining gear 49 increases a depth of bending formed on the horizontal surface Ia of the sheet 1 due to meshing of the gears, thereby decreasing a diameter of the outer ring 200. On the other hand, a great gap therebetween narrows a depth of bending, thereby increasing a diameter of the outer ring 200.

[103] Accordingly, the lower machining gear 49 has an up-down shaft 42 moving up and down by a fifth motor 41 fixed to a lower end thereof. Also, the fifth motor 41 is driven in response to a control signal of the controller 50 so that the fifth motor 41 is automatically driven by the set value of the controller 50 to move the up-down shaft 42 up and down. This in turn moves the lower machining gear 49 assembled with the up- down shaft 42 up and down, thereby adjusting a gap with the upper machining gear 48 to suit the set value.

[104] This varies a depth of bending of the sheet 1 in accordance with the set value of the controller 50, thereby machining the outer ring 200 having various diameters in accordance with the set value. Also, the outer ring 200 completed is finally dropped off

into the collection box B for collection.

[105] As set forth above, according to preferred embodiments of the invention, a steel sheet is automatically supplied by an uncoiler of a supplier. The supplied sheet is cut to a predetermined length by a cutting part. The cut sheet is converted from a horizontal transfer direction to a vertical transfer direction by a converting part to be easily bent. The sheet converted to a vertical direction is bent at a right angle while passing through a machining part, and a horizontal surface of the bent sheet is bent into a circle to manufacture an outer ring, thereby protecting an outer circumference of a coil. Unlike the prior art, the sheet for the outer ring needs not be cut or transferred manually. Thus according to the invention, all processes are automated to manufacture the outer ring with precise dimensions through a smooth process flow. This accordingly produces the outer ring with various diameters precisely, thereby significantly enhancing manufacturing efficiency and ensuring labor safety with minimal manual work involved.

[106] While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.