Scribing device for trisecting outer surface of steel pipe in circumferential direction

Abstract

The utility model discloses a scribing device for trisecting the outer surface of a steel pipe in the circumferential direction, and belongs to the technical field of scribing equipment for steel pipe machining. The scribing device for trisecting the outer surface of the steel pipe in the circumferential direction comprises a first support, a second support, six third supports, three fourth supports, three fifth supports, three sixth supports, six linear bearings, three refills, sixty-six screws, six rolling bearings and three springs. The device can achieve the purpose of trisection longitudinal scribing in the circumferential direction of the outer surface of the steel pipe, and has the advantages of being low in manufacturing cost, easy to operate and good in using effect.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of the steel pipe processing marking device, concretely relates to a marking device that is used for three equal division of the circumference of the outer surface of a steel pipe. BACKGROUND

[0002] At present, compared with other section profiles, steel pipes have relatively high resistance to bending and resistance to torsion; therefore, steel pipes have been widely used in the field of mechanical manufacturing and the field of structural engineering; sometimes, it is necessary to perform three equal division marking operation on the circumference of the outer surface of a steel pipe so as to process grooves on the outer surface of the steel pipe, calibrate installation positions or measure external dimensions, but there are relatively few professional devices for three equal division marking on the circumference of the outer surface of a steel pipe, and enterprises usually use a right-angle caliper to perform longitudinal marking on the outer surface of a steel pipe, but the marking precision and marking efficiency of this method are relatively limited.

[0003] After searching, it is found that there are three patent documents and the utility model technology is most relevant, and the specific content is described as follows:

[0004] Patent document CN 02258314.9 discloses a simple device for three equal division of an angle and an arc, which mainly comprises a semi-moving control rod, a full-moving control rod, a short angle dividing straight rod and a long angle dividing straight rod, the device is novel in design and ingenious in conception, an angle can be three equally divided through twice joint use of the feature that the diagonals of a rhombus divide the angle, according to the feature that the arc length corresponding to the equal central angles in a circle is also equal, the arc length is further three equally divided, and the device has the characteristics of simple structure and rapid and efficient, but the device is only suitable for three equal division of an angle or an arc, and is not suitable for three equal division marking on the circumference of the outer surface of a steel pipe.

[0005] Patent document CN 201720376394.X discloses a special device for three equal division punching of a lathe tailstock, which mainly comprises a handle, a three equal division positioning disc, a connecting shaft, a three equal division positioner, a spring and a drill bit, the device is novel in design and ingenious in conception, the three equal division positioner is designed, and the slope of the three equal division positioner is optimized to ensure that the processed product is kept horizontal with the lathe, so as to facilitate processing, and the device has the characteristics of simple structure, accurate punching and high material yield, but the device is only suitable for three equal division punching of a lathe tailstock, and is not suitable for three equal division marking on the circumference of the outer surface of a steel pipe.

[0006] The patent document CN201420282356.4 discloses a pipe three-equal-division sawing device, which mainly comprises a base plate, V-shaped blocks, movable blocks, fixed blocks, mandrels, saw blades, bolts and screws. The device has the characteristics of novel design, ingenious concept, equal angles between three sawing surfaces, simple structure, accurate sawing and high efficiency. However, the device is only suitable for three-equal-division sawing of pipes and is not suitable for three-equal-division marking on the outer surface of a steel pipe. Practical new type content

[0007] In order to overcome one or more of the problems existing in the prior art, the utility model provides a marking device for three-equal-division of the outer surface of a steel pipe. The utility model is designed based on a symmetrical structure. The use of screws can realize linkage of the second support and the linear bearing and linkage of the fifth support and the second support. The use of the linear bearing and the first support can realize vertical lifting of the second support. The use of the fifth support and the screws can realize relative arrangement of the six third supports and three-way arrangement of the three sixth supports. The use of the third support and the rolling bearing can realize positioning and swinging of the sixth support. The use of the sixth support and the fourth support can realize positioning of the pen core. The use of the spring can realize three-equal-division marking of the pen core on the circumference of the outer surface of the steel pipe. Therefore, the utility model has relatively good use effect.

[0008] The technical solution adopted by the utility model to solve the technical problems is as follows.

[0009] The marking device for three-equal-division of the outer surface of a steel pipe comprises a first support, a second support, six third supports, three fourth supports, three fifth supports, three sixth supports, six linear bearings, three pen cores, sixty-six screws, six rolling bearings and three springs.

[0010] The first support is composed of a first body, three first bosses and three second bosses. The first body is a symmetrical structure in the shape of a regular triangular prism. The three first bosses are arranged in the shape of a regular triangle and are located on the upper end surface of the first body. The three second bosses are arranged in the shape of a regular triangle and are located on the upper end surface of the first body. The first boss is a symmetrical structure in the shape of a cylinder and is used for penetrating the fourth through hole of the linear bearing. The second boss is a symmetrical structure in the shape of a cylinder and is used for positioning the steel pipe from the outside.

[0011] The second support is connected by a second body, six third bosses and six fourth bosses, the second body and the fourth bosses are symmetrical structures of regular triangular prism, the third bosses are symmetrical structures of cuboid, six third bosses are oppositely arranged in pairs and are located on the upper and lower end faces of the second body, six fourth bosses are oppositely arranged in pairs and are located on the upper and lower end faces of the second body; a first through hole in the shape of a regular triangular prism is formed in the middle part of the second body, and a steel pipe is arranged in the first through hole; four first screw holes are symmetrically formed in the third boss, and the screws are screwed in the first screw holes; a second through hole in the shape of a cylinder is formed in the central part of the fourth boss, the fifth boss of the linear bearing is arranged in the second through hole, and the second through hole penetrates the second body; a second screw hole is formed in each of the three corner parts of the fourth boss, and the screw is screwed in the second screw hole;

[0012] The third support is connected by a fourth body and a sixth boss, the fourth body and the sixth boss are symmetrical structures of cuboid, the sixth boss is located on the rear end face of the fourth body; a first recess in the shape of a cylinder is formed in the middle part of the right end face of the fourth body, and the rolling bearing is arranged in the first recess; a fifth through hole in the shape of a cylinder is formed in the axis part of the first recess, and the bearing segment of the sixth support is arranged in the fifth through hole; four sixth through holes in the shape of a cylinder are symmetrically formed in the sixth boss, and the screws are arranged in the sixth through holes;

[0013] The fourth support is connected by a coaxial fifth body and a seventh boss, the fifth body and the seventh boss are symmetrical structures of cylinder, the seventh boss is located on the upper end face of the fifth body; a second recess in the shape of a cylinder is formed in the axis part of the lower end face of the fifth body, and the pen core is arranged in the second recess, and the fifth body is provided with internal threads at the end part for screwing the external threads of the sixth support; a seventh through hole in the shape of a cylinder is formed in the axis part of the seventh boss, and the pen core is arranged in the seventh through hole, and the seventh through hole and the second recess are coaxially connected;

[0014] The fifth support is connected by a sixth body, an eighth boss, two ninth bosses and two tenth bosses, the sixth body, the eighth boss, the ninth boss and the tenth boss are all cuboid symmetrical structures, the eighth boss is located at the front end surface of the sixth body, the two ninth bosses are oppositely arranged and located at the front end surface of the eighth boss, and the two tenth bosses are oppositely arranged and located at the upper end surface of the sixth body; a cuboid-shaped through groove can be formed between the two ninth bosses, and the third boss of the second support is arranged in the through groove; the ninth boss is symmetrically provided with four eighth through holes in the form of cylinders, and the screw is arranged in the eighth through hole; the tenth boss is symmetrically provided with four third screw holes, and the screw is screwed in the third screw hole.

[0015] The sixth support is connected by a seventh body, an eleventh boss and two bearing segments, the seventh body is a cuboid symmetrical structure, the eleventh boss is located at the upper end surface of the seventh body, and the two bearing segments are oppositely arranged and located at the left and right end surfaces of the seventh body; the eleventh boss is a cylindrical symmetrical structure, an axis part of the eleventh boss is provided with a ninth through hole in the form of a cylinder, and the pen core is arranged in the ninth through hole; a third recess in the form of a cylinder is formed in the central part of the upper end surface of the seventh body, and the spring and the pen core are arranged in the third recess, and the third recess and the ninth through hole are coaxially connected; the end part of the eleventh boss is provided with external threads for screwing the internal threads of the fourth support; the bearing segment is a cylindrical symmetrical structure for arranging the rolling bearing.

[0016] In some embodiments, the linear bearing is connected by a third body and a fifth boss, the third body is a regular triangular prism symmetrical structure, and the fifth boss is located at the upper end surface of the third body; three corner parts of the third body are respectively provided with a third through hole in the form of a cylinder, and the screw is arranged in the third through hole; the fifth boss is a cylindrical symmetrical structure, an axis part of the fifth boss is provided with a fourth through hole in the form of a cylinder, the first boss of the first support is arranged in the fourth through hole, the fourth through hole also penetrates the third body, and the fifth boss is further provided with a retainer, balls and a check ring.

[0017] In some embodiments, the pen core, the screw, the rolling bearing and the spring are all standard parts.

[0018] The beneficial effects of the utility model are as follows:

[0019] 1) The line marking device for three equal division of the circumference of the outer surface of the steel pipe comprises a first support, a second support, six third supports, three fourth supports, three fifth supports, three sixth supports, three linear bearings, three pen cores, sixty-six screws, six rolling bearings and three springs, since the material is common and is convenient for processing, the manufacturing cost of the device is relatively low.

[0020] 2) When the device is used, the three sixth supports are in the folded state, the steel pipe is vertically arranged on the first body of the first support, and the four second bosses are arranged outside the steel pipe, at this time, the three sixth supports are arranged upwards, ①, ② and ③ are simultaneously rotated by 90 degrees, then the three sixth supports in three directions are horizontally arranged, the six linear bearings are uniformly moved upwards along the three first bosses of the first support, so that the three sixth supports can be uniformly vertically moved, and the three pen cores can be longitudinally marked on the circumference of the outer surface of the steel pipe, therefore, the operation of the device is relatively simple.

[0021] 3) The device is designed based on the symmetrical structure, the use of the screws can realize linkage of the second support and the linear bearing, linkage of the fifth support and the second support, the combined use of the linear bearing and the first support can realize vertical lifting of the second support, the combined use of the fifth support and the screw can realize relative arrangement of the six third supports, and then realize three-way arrangement of the three sixth supports, the combined use of the third support and the rolling bearing can realize positioning and rotation of the sixth support, the combined use of the sixth support and the fourth support can realize positioning of the pen core, and the use of the spring can realize three equal division of the circumference of the outer surface of the steel pipe, therefore, the use effect of the device is relatively good.

[0022] The line marking device for three equal division of the circumference of the outer surface of the steel pipe can realize three equal division of the circumference of the outer surface of the steel pipe, and has the characteristics of low manufacturing cost, simple operation and good use effect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a front view structural schematic diagram of the line marking device for three equal division of the circumference of the outer surface of the steel pipe when the sixth support is in the folded state.

[0024] Figure 2 It is a front view structural schematic diagram of the line marking device for three equal division of the circumference of the outer surface of the steel pipe when the sixth support is in the folded state.

[0025] Figure 3The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0026] Figure 4 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0027] Figure 5 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0028] Figure 6 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0029] Figure 7 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0030] Figure 8 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0031] Figure 9 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0032] Figure 10 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0033] Figure 11 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0034] Figure 12 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0035] Figure 13 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0036] Figure 14 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0037] Figure 15 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0038] Figure 16 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0039] Figure 17 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0040] Figure 18 The main view structural schematic drawing of the fourth support, the pen core, the spring and the sixth support of the utility model is shown in the figure;

[0041] Figure 19 It is the right view structural schematic drawing of the fifth support of the utility model;

[0042] Figure 20 It is the plan view structural schematic drawing of the fifth support of the utility model;

[0043] Figure 21 It is the front view structural schematic drawing of the sixth support of the utility model;

[0044] Figure 22 It is the plan view structural schematic drawing of the sixth support of the utility model;

[0045] Figure 23 It is the section view structural schematic drawing of the sixth support along the N-N plane of the utility model;

[0046] Figure 24 It is the schematic diagram of the observation direction of the sixth support of the utility model;

[0047] Figure 25 It is the schematic diagram of the forward rotation swing of the sixth support of the utility model;

[0048] Figure 26 It is the schematic diagram of the reverse rotation swing of the sixth support of the utility model;

[0049] Figure 27 It is the working principle schematic diagram of the marking device for three equal division of the outer surface circumference of the steel pipe of the utility model.

[0050] BRIEF DESCRIPTION OF DRAWINGS 1- first support; 101- first body; 102- first boss; 103- second boss; 2- second support; 201- second body; 202- third boss; 203- fourth boss; 204- first through hole; 205- first screw hole; 206- second through hole; 207- second screw hole; 3- linear bearing; 301- third body; 302- fifth boss; 303- third through hole; 304- fourth through hole; 4- third support; 401- fourth body; 402- sixth boss; 403- first recess; 404- fifth through hole; 405- sixth through hole; 5- fourth support; 501- fifth body; 502- seventh boss; 503- second recess; 504- seventh through hole; 6- fifth support; 601- sixth body; 602- eighth boss; 603- ninth boss; 604- tenth boss; 605- through slot; 606- eighth through hole; 607- third screw hole; 7- sixth support; 701- seventh body; 702- eleventh boss; 703- bearing section; 704- third recess; 705- ninth through hole; 8- pen core; 9- screw; 10- rolling bearing; 11- spring; 12- steel pipe. DETAILED DESCRIPTION

[0051] The content of the utility model is explained in detail below by examples and drawings, and the examples are only for understanding the utility model, and do not limit the content of the utility model.

[0052] As shown in the combination Figures 1 to 5 The utility model provides a kind of scribing device to the three equal division of steel pipe outer surface circumference, it includes a first support 1, a second support 2, six third supports 4, three fourth supports 5, three fifth supports 6, three sixth supports 7, six linear bearings 3, three pen cores 8, sixty-six screws 9, six rolling bearings 10 and three springs 11;Wherein, six third bosses 202 of the second support 2 are arranged in three through slots 605 of three fifth supports 6, and are connected by twenty-four screws 9;Six sixth bosses 402 of six third supports 4 are provided outside the six end faces of six tenth bosses 604 of three fifth supports 6, and are connected by twenty-four screws 9;Six rolling bearings 10 are arranged in six first recesses 403 of six third supports 4, and six bearing segments 703 of three sixth supports 7 are arranged in six rolling bearings 10;Three third recesses 704 and three ninth through holes 705 of three sixth supports 7 are arranged with a part of three springs 11 and three pen cores 8, and another part of three pen cores 8 is arranged in three second recesses 503 and three seventh through holes 504 of three fourth supports 5, and three fourth supports 5 and three sixth supports 7 are connected by internal thread and external thread;Six fifth bosses 302 of six linear bearings 3 are arranged in three second through holes 206 of the second support 2, and are connected by eighteen screws 9, and three first bosses 102 of the first support 1 are arranged in six fourth through holes 304 of six linear bearings 3.

[0053] The assembly process of the scribing device for the three equal division of steel pipe outer surface circumference provided by the utility model

[0054] As shown in the combination Figures 1 to 23 First, the second support 2 is arranged horizontally, then six fifth bosses 302 of six linear bearings 3 are arranged in three second through holes 206 of the second support 2 in pairs, and eighteen third through holes 303 of six linear bearings 3 and eighteen second screw holes 207 of the second support 2 are aligned, then eighteen screws 9 are arranged through eighteen third through holes 303 and are screwed into eighteen second screw holes 207, so that six linear bearings 3 and the second support 2 can be assembled.

[0055] Then, three through grooves 605 of the fifth support 6 are respectively sleeved outside upper and lower six end faces of six third bosses 202 of the second support 2, twenty-four eighth through holes 606 of the fifth support 6 are centered with twenty-four first screw holes 205 of the second support 2, then twenty-four screws 9 are passed through the twenty-four eighth through holes 606 and screwed into the twenty-four first screw holes 205, so that the fifth support 6 and the second support 2 are assembled;

[0056] Then, six first recesses 403 of the third support 4 are installed with six rolling bearings 10, then the third support 4 is arranged oppositely in pairs, six bearing segments 703 of the sixth support 7 are respectively passed through the six rolling bearings 10, so that the third support 4, the rolling bearing 10 and the sixth support 7 are assembled;

[0057] Then, six sixth bosses 402 of the third support 4 are respectively sleeved outside six end faces of six tenth bosses 604 of the fifth support 6, twenty-four sixth through holes 405 of the third support 4 are centered with twenty-four third screw holes 607 of the fifth support 6, then twenty-four screws 9 are passed through the twenty-four sixth through holes 405 and screwed into the twenty-four third screw holes 607, so that the third support 4 and the fifth support 6 are assembled;

[0058] Then, three springs 11 and a part of three refills 8 are passed through three third recesses 704 and three ninth through holes 705 of the sixth support 7 in sequence, then another part of the three refills 8 is respectively passed through three second recesses 503 and three seventh through holes 504 of the fourth support 5, then the fourth support 5 and the sixth support 7 are screwed through internal threads and external threads, so that the sixth support 7, the spring 11, the refill 8 and the fourth support 5 are assembled;

[0059] Then, the first support 1 is horizontally arranged, four second bosses 103 are arranged upwards at the same time, finally, three first bosses 102 of the first support 1 are respectively passed through six fourth through holes 304 of the linear bearing 3, so that the whole device is assembled and can be used.

[0060] The sixth support of the marking device for three equal division of the outer surface of the steel pipe is rotatably arranged in the direction defined by the rule

[0061] The sixth support of the marking device for three equal division of the outer surface of the steel pipe is rotatably arranged in the direction defined by the ruleFigures 1 to 4 As shown, for ease of description, we can take the direction of the fourth support 5 when it is located on the right side as the observation direction, which will be simplified as follows: Figure 24 As shown, there are three observation directions in total. Let's define the three observation directions as ①, ② and ③ respectively. Among them, the six bearing segments 703 of the three sixth supports 7 are all swing shafts.

[0062] Assuming that initially all three sixth supports 7 are folded, i.e., all three sixth supports 7 are facing upwards, then the three pen refills 8 cannot draw lines. (Simplified version follows...) Figure 25 As shown, if ①, ② and ③ simultaneously rotate 90 degrees clockwise, then all three sixth supports 7 will be horizontally positioned. We can define this rotation direction of the three sixth supports 7 as positive.

[0063] Assuming that initially all three sixth supports 7 are in an extended position, i.e., all three sixth supports 7 are in a horizontal position, then the three pen refills 8 can draw lines. (Simplified version follows...) Figure 26 As shown, if ①, ② and ③ simultaneously rotate 90 degrees counterclockwise, then all three sixth supports 7 will be facing upwards. We can define this rotation direction of the three sixth supports 7 as reverse.

[0064] The working principle of the marking device for dividing the outer surface of a steel pipe into three equal parts in the circumferential direction provided by this utility model

[0065] like Figure 4 As shown in the top view of the device of this utility model, for ease of description, the three longitudinal straight lines drawn by the three pen refills 8 are defined as points A, B, and C, respectively; the axis of the steel pipe 12 is defined as point O; and the three side edges of the second body 201 of the second bracket 2 are defined as points D, E, and F, respectively. Connect points O and A, and extend the line segment EF to intersect at point G; connect points O and B, and extend the line segment FD to intersect at point H; connect points O and C, and extend the line segment DE to intersect at point I, as shown in the diagram. Figure 27 As shown;

[0066] Based on the knowledge that the sum of the interior angles of a planar quadrilateral is 360°, in quadrilateral OGEI, ∠OGE + ∠GEI + ∠EIO + ∠IOG = 360°; since this utility model adopts a symmetrical structure, line segment OG is perpendicular to and bisects line segment EF, line segment OH is perpendicular to and bisects line segment FD, and line segment OI is perpendicular to and bisects line segment DE, that is, ∠OGE = ∠EIO = 90°; since the second body 201 of the second support 2 is a regular triangular prism, ∠GEI = 60°, from which it can be deduced that ∠IOG = 120°;

[0067] The same method can be deduced ∠GOH = ∠HOI = 120 °, since ∠COA = ∠IOG = 120 °, ∠AOB = ∠GOH = 120 °, ∠BOC = ∠HOI = 120 °, therefore, ∠COA = ∠AOB = ∠BOC, according to the same circle, the equal center angle corresponding to the arc length is also equal, arc CA = arc AB = arc BC, point A, point B, point C divides the entire outer circumference; since the spring 11 has a self-balancing function, three said pen core 8 can be three equal division of the circumference of the steel pipe 12 outer surface.

[0068] The use method of the line marking device for three equal division of the circumference of the steel pipe outer surface

[0069] Step one: combination Figure 1 As shown in the initial three sixth support 7 are in the folded setting, first set the steel pipe 12 is set in the first body 101 of the first support 1, and four second boss 103 are all set outside the steel pipe 12, at this time, the steel pipe 12 is set in the first through hole 204 of the second support 2;

[0070] Step two: combination Figure 25 At this time, three sixth support 7 are all set upward, then the ①, the ② and the ③ are simultaneously forward swing 90 degrees, then three sixth support 7 in three directions are changed into horizontal setting, so as to facilitate three pen core 8 to mark line;

[0071] Step three: then along the three first boss 102 of the first support 1, move six straight line bearings 3 upward at a constant speed, so that three sixth support 7 can move vertically upward at a constant speed, during which three sixth support 7 cannot swing, three pen core 8 can be three equal division of the circumference of the steel pipe 12 outer surface in the longitudinal direction, as shown in Figure 4 .

[0072] Supplementary note: the line marking device for three equal division of the circumference of the steel pipe outer surface provided by the utility model adopts symmetrical structure design, first of all, according to the outer diameter specification of the steel pipe and the fixed length of the steel pipe, a plurality of specifications of the utility model device matched with it should be designed and manufactured; the spring should be slightly compressed in advance, that is, a compression force is applied to the spring in advance, so as to ensure that the pen core can contact the outer surface of the steel pipe by means of elastic force, and make three equal division of the longitudinal line in the circumferential direction.

[0073] It can be seen from the embodiments that the marking device which is used for three equal division of the outer surface of the steel pipe can achieve the purpose of three equal division of the longitudinal marking in the circumferential direction of the outer surface of the steel pipe, and the device has the characteristics of low manufacturing cost, simple operation and good use effect.

[0074] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the foregoing detailed description of the present application is made with reference to the foregoing embodiments, for those skilled in the art, it still can be modified to the technical solutions recorded in the foregoing embodiments, or equivalent replacement of some of the technical features.

Claims

1. A scribing device for dividing the circumference of a steel pipe into three equal parts, characterized in that, The marking device for dividing the outer surface of the steel pipe into three equal parts circumferentially includes: a first support (1), a second support (2), six third supports (4), three fourth supports (5), three fifth supports (6), three sixth supports (7), six linear bearings (3), three pen refills (8), sixty-six screws (9), six rolling bearings (10), and three springs (11), wherein: The first bracket (1) is composed of a first body (101), three first protrusions (102) and three second protrusions (103) connected together. The first body (101) is a symmetrical structure in the shape of a regular triangular prism. The three first protrusions (102) are arranged in an equilateral triangle and are located on the upper end face of the first body (101). The three second protrusions (103) are arranged in an equilateral triangle and are located on the upper end face of the first body (101). The first protrusions (102) are symmetrical structures in the shape of cylinders and are used to pass through the fourth through hole (304) of the linear bearing (3). The second protrusions (103) are symmetrical structures in the shape of cylinders and are used to position the steel pipe from the outside. The second bracket (2) is composed of a second body (201), six third protrusions (202) and six fourth protrusions (203) connected together. The second body (201) and the fourth protrusions (203) are both symmetrical structures in the shape of regular triangular prisms. The third protrusions (202) are symmetrical structures in the shape of cuboids. The six third protrusions (202) are arranged opposite each other in pairs and are respectively located on the upper and lower end faces of the second body (201). The six fourth protrusions (203) are arranged opposite each other in pairs and are respectively located on the upper and lower end faces of the second body (201). A first through hole (203) in the shape of a regular triangular prism is opened in the middle part of the second body (201). 04), a steel pipe is inserted into the first through hole (204); the third boss (202) is symmetrically provided with four first screw holes (205), and the screw (9) is screwed into the first screw hole (205); the fourth boss (203) is provided with a cylindrical second through hole (206) at the center, and the fifth boss (302) of the linear bearing (3) is inserted into the second through hole (206), and the second through hole (206) also penetrates the second body (201); the third corner of the fourth boss (203) is provided with a second screw hole (207), and the screw (9) is screwed into the second screw hole (207); The third bracket (4) is composed of a fourth body (401) and a sixth boss (402). The fourth body (401) and the sixth boss (402) are both symmetrical rectangular parallelepiped structures. The sixth boss (402) is located on the rear end face of the fourth body (401). A cylindrical first groove (403) is opened in the middle part of the right end face of the fourth body (401). The rolling bearing (10) is inserted in the first groove (403). A cylindrical fifth through hole (404) is opened in the axial part of the first groove (403). The bearing section (703) of the sixth bracket (7) is inserted in the fifth through hole (404). The sixth boss (402) is symmetrically provided with four cylindrical sixth through holes (405). The screw (9) is inserted in the sixth through hole (405). The fourth bracket (5) is composed of a fifth body (501) and a seventh protrusion (502) connected coaxially. The fifth body (501) and the seventh protrusion (502) are both cylindrical symmetrical structures. The seventh protrusion (502) is located on the upper end face of the fifth body (501). A cylindrical second groove (503) is opened at the axial part of the lower end face of the fifth body (501). The pen refill (8) is inserted in the second groove (503). The end of the fifth body (501) is provided with an internal thread for screwing the external thread of the sixth bracket (7). A cylindrical seventh through hole (504) is opened at the axial part of the seventh protrusion (502). The pen refill (8) is inserted in the seventh through hole (504). The seventh through hole (504) and the second groove (503) are coaxially connected. The fifth bracket (6) is composed of a sixth body (601), an eighth protrusion (602), two ninth protrusions (603), and two tenth protrusions (604). The sixth body (601), the eighth protrusion (602), the ninth protrusion (603), and the tenth protrusion (604) are all symmetrical cuboid structures. The eighth protrusion (602) is located on the front end face of the sixth body (601). The two ninth protrusions (603) are arranged opposite each other and are simultaneously located on the front end face of the eighth protrusion (602). The two tenth protrusions (604) The two ninth protrusions (603) are positioned opposite each other and located on the upper surface of the sixth body (601); a cuboid through groove (605) can be formed between the two ninth protrusions (603), and the third protrusion (202) of the second bracket (2) is inserted through the through groove (605); the ninth protrusion (603) is symmetrically provided with four cylindrical eighth through holes (606), and the screw (9) is inserted through the eighth through hole (606); the tenth protrusion (604) is symmetrically provided with four third screw holes (607), and the screw (9) is screwed into the third screw hole (607); The sixth bracket (7) is composed of a seventh body (701), an eleventh boss (702), and two bearing segments (703). The seventh body (701) is a symmetrical rectangular parallelepiped structure. The eleventh boss (702) is located on the upper end face of the seventh body (701). The two bearing segments (703) are arranged opposite to each other and are located on the left and right end faces of the seventh body (701), respectively. The eleventh boss (702) is a symmetrical cylindrical structure. A cylindrical ninth through hole (705) is opened at the axial part of the eleventh boss (702). The pen refill (8) is inserted through the ninth through hole (705); a cylindrical third groove (704) is provided at the center of the upper end face of the seventh body (701), and the spring (11) and the pen refill (8) are inserted through the third groove (704). The third groove (704) and the ninth through hole (705) are coaxially connected; the end of the eleventh boss (702) is provided with an external thread for screwing the internal thread of the fourth bracket (5); the bearing section (703) is a cylindrical symmetrical structure for inserting the rolling bearing (10).

2. The scribing device for dividing the circumference of the outer surface of a steel pipe into three equal parts according to claim 1, characterized in that, The linear bearing (3) is composed of a third body (301) and a fifth boss (302). The third body (301) is a symmetrical structure in the shape of a regular triangular prism. The fifth boss (302) is located on the upper end face of the third body (301). A cylindrical third through hole (303) is opened at each of the three corners of the third body (301). The screw (9) is inserted inside the third through hole (303). The fifth boss (302) is a symmetrical structure in the shape of a cylinder. A cylindrical fourth through hole (304) is opened at the axial part of the fifth boss (302). The first boss (102) of the first bracket (1) is inserted inside the fourth through hole (304). The fourth through hole (304) also penetrates the third body (301). A cage, ball and retainer are also provided inside the fifth boss (302).

3. The scribing device for dividing the circumferential surface of a steel pipe into three equal parts according to claim 1, characterized in that, The pen refill (8), the screw (9), the rolling bearing (10), and the spring (11) are all standard parts.

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