阅读说明：本技术 一种不锈钢折弯机 (Stainless steel bending machine ) 是由 马夏康 李建波 陈志伟 尹谢平 于 2021-08-03 设计创作，主要内容包括：本发明公开了一种不锈钢折弯机,包括底板、固定于底板上的定模固定组件、固定于定模固定组件上方的定模组件；所述定模组件内设有直径相同且分别用于固定直钢管的圆通孔和用于固定90°定角弯头的90°弯头通孔；所述定模组件在输出口的一侧设有用于折弯导向的R角模,所述R角模开有R角模圆弧凹槽,所述R角模圆弧凹槽的轴线与输出口的轴线相接且共面；底板上还垂直固定有旋转轴,旋转轴通过轴承连接有齿轮齿条机构,齿条连接有驱动组件；齿轮上方设有动模,动模的一侧设置与R角模圆弧凹槽的轴线共线的动模圆弧凹槽。本发明解决了异形结构弯头折弯成型成本昂贵、操作繁琐的问题,实现两个方向90°定角和0-180°变角弯头的制作。(The invention discloses a stainless steel bending machine which comprises a base plate, a fixed die fixing component fixed on the base plate, and a fixed die component fixed above the fixed die fixing component; a circular through hole with the same diameter and used for fixing a straight steel pipe and a 90-degree elbow through hole used for fixing a 90-degree fixed-angle elbow are formed in the fixed die assembly; an R angle die for bending and guiding is arranged on one side of the output port of the fixed die assembly, an R angle die arc groove is formed in the R angle die, and the axis of the R angle die arc groove is connected with and coplanar with the axis of the output port; a rotating shaft is also vertically fixed on the bottom plate, the rotating shaft is connected with a gear rack mechanism through a bearing, and a rack is connected with a driving assembly; a movable mould is arranged above the gear, and one side of the movable mould is provided with a movable mould arc groove which is collinear with the axis of the R angle mould arc groove. The invention solves the problems of high cost and complex operation of bending and forming of the special-shaped structure elbow, and realizes the manufacture of the elbow with the fixed angle of 90 degrees and the variable angle of 0-180 degrees in two directions.)

1. A stainless steel bending machine is characterized by comprising a base plate, a fixed die fixing component fixed on the base plate, and a fixed die component fixed above the fixed die fixing component;

a circular through hole for fixing a straight steel pipe and a 90-degree elbow through hole for fixing a 90-degree fixed-angle elbow are formed in the fixed die assembly, the diameters of the circular through hole and the 90-degree elbow through hole are the same, and the circular through hole and the 90-degree elbow through hole share one output port;

an R angle die for bending and guiding is arranged on one side of the output port of the fixed die assembly, an R angle die arc groove is formed in the R angle die, and the axis of the R angle die arc groove is connected with and coplanar with the axis of the output port;

a rotating shaft is also vertically fixed on the bottom plate; the rotating shaft is connected with a gear rack mechanism through a bearing; the rack on the gear rack mechanism is connected with a driving assembly, a movable die is arranged above a gear on the gear rack mechanism, one side of the movable die is provided with a movable die arc groove, the axis of the movable die arc groove and the axis of the R angle die arc groove are collinear, and the driving assembly is provided with a displacement sensor and a control system.

2. The stainless steel bending machine according to claim 1, wherein the fixed die assembly comprises a first fixed die and a second fixed die which are separated along the axial direction of the circular through hole and the 90-degree elbow through hole, the first fixed die and the second fixed die are matched, and the first fixed die and the second fixed die are positioned through an inserting plate and a positioning pin.

3. The stainless steel bending machine according to claim 1, wherein the fixed die fixing assembly comprises a fixed die fixing column welded at the bottom to the base plate and a fixed die base plate welded above the fixed die fixing column; the fixed die assembly and the R angle die are fixed on the fixed die base plate through bolts.

4. The stainless steel bending machine according to claim 1, wherein a boss for connection is arranged at the upper part of the gear, a movable die base plate is connected to the boss through bolts, and the movable die base plate is connected with the movable die through bolts.

5. The stainless steel bending machine according to claim 1, wherein the R-angle die arc groove and the movable die arc groove are semicircular grooves having the same inner diameter.

6. The stainless steel bending machine according to claim 1, wherein said drive assembly comprises a hydraulic ram, and wherein said displacement sensor is built into said hydraulic ram.

7. A bending method based on the stainless steel bending machine according to any one of claims 1 to 6, comprising the following steps:

(1) calculating the minimum bending radius of the steel pipe to be bent;

(2) calculating the minimum bending force of the steel pipe, and verifying the thrust of the driving assembly;

(3) verifying the stroke of the driving assembly through the matching movement distance of the rack and the gear;

(4) selecting a matched fixed die assembly and a matched movable die according to the specification of a steel pipe to be bent; selecting a matched R angle die according to the bending R angle of the steel pipe to be bent;

(5) the control system drives the driving assembly to operate, the movable die is located at the position where the axis of the arc groove is collinear with the axis of the output port, the position is set to be an original position through the position sensor, the specification parameters of the rack and pinion mechanism and the angle of the steel pipe to be bent are input into the control system of the driving assembly, the control system sets the operation distance of the rack through the position sensor, and the control system drives the driving assembly to operate to the distance set by the position sensor.

8. A bending method according to claim 7, wherein in the step (2), the steps of calculating the minimum bending force of the steel tube and verifying the thrust force of the driving assembly are as follows:

(2-1) calculating the bending moment of the steel pipe through the generalized Huke's law:

M＝σ·W

σ＝E·ε

W＝π(D⁴-d⁴)/16D

wherein, sigma is the normal stress on the radial section of the steel pipe, W is the section modulus of the radial section of the steel pipe, M is the bending moment of the steel pipe, E is the elastic modulus of the steel pipe, epsilon is the axial line strain of the steel pipe, D is the outer diameter of the steel pipe, and D is the inner diameter of the steel pipe;

(2-2) calculating the minimum bending force of the steel pipe according to the simply supported beam model:

F＝4M/L

L＝6R+3D

wherein R is the minimum bending radius of the steel pipe, F is the minimum bending force, and L is the span of the simply supported beam;

(2-3) verifying that the thrust of the driving assembly needs to meet the following requirements according to the minimum bending force of the steel pipe obtained in the step (2-2):

F′＞F/η

wherein, F' is the thrust of the driving assembly, and eta is the actual working efficiency of the driving assembly.

9. A bending method according to claim 7, wherein in the step (3), the movement distance of the rack and the gear is as follows:

l＝π×d₁×180°/360°

d₁＝mz

wherein d is₁The diameter of a reference circle, m is the gear module, and z is the number of teeth of a gear;

then, the stroke of the driving assembly needs to satisfy: l₁≥l+l′

Wherein l₁For the working stroke of the driving assembly, l' is reserved for safety.

Technical Field

The invention relates to the technical field of machining, in particular to a stainless steel bending machine.

Background

The elbow connecting piece is widely applied to the industries of natural gas pipeline connection, fire fighting, automatic water supply, automatic water spraying and the like, medical equipment, municipal water supply and the like.

The stainless steel elbow is widely applied to various industries due to the unique corrosion resistance of the stainless steel elbow, and a plurality of stainless steel elbow equipment manufacturers appear in the market.

One part of the traditional bending machine is applied to bending of a complicated special-shaped structure elbow, and the traditional bending machine is complicated in equipment and complex in operation; the other part is applied to bending of the elbow with a single angle, the equipment structure is simple, and the elbow bending machine is only suitable for bending the elbow with a simple forming structure.

When the elbow with multiple angles needs to be processed at the present stage, the following modes are adopted:

firstly, purchasing and casting a threaded connection elbow, wherein the elbow has a rough surface, poor sealing performance on a high-pressure pipeline and unstable firmness; if the two directions are required to be connected, a plurality of elbows are required to be connected, and the hidden danger of leakage is increased.

The second kind, according to on-the-spot actual conditions, the manual thermoforming elbow, this kind of simple manual book mode, when technology spare is made, there is following drawback:

1) the qualification rate is low, and the bending surfaces are difficult to control on the same plane, so that the steel pipe is often twisted;

2) the deformation of the workpiece is large, and the consistency and the interchangeability are poor;

3) the outer side of the workpiece has tension cracks, and the inner side of the workpiece has a wrinkle phenomenon;

4) when the elbow is formed by heating, a zinc coating, an anti-rust layer and an anti-oxidation layer of the elbow part are easy to damage, so that the elbow is easy to rust and oxidize in the using process;

5) for the special-shaped space pipeline connecting structure, if the elbows in two directions need to be bent simultaneously, the manual bending difficulty is higher.

Thirdly, connecting the pipelines in the special-shaped space in a welding mode; the more welding points, the more hidden troubles such as welding failure, infirm welding and the like, and the whole appearance is not beautiful.

The specification with the publication number of CN 103658250 a discloses an automatic synchronous bending machine, which mainly solves the problems that the existing bending machine needs a person to push a workpiece to a bending abutment and the person assists in bending. The belt conveying device consisting of the belt, the belt conveying support, the servo motor, the belt pulley, the magnet and the like completes the function of pushing the workpiece to the leaning part of the bending machine by a person. The fully-servo synchronous material supporting device which consists of a large circular arc gear, a first bearing, a second bearing, a roller gear, a sliding block bracket, a gear rack oil cylinder, an oil cylinder bracket, an energy storage oil cylinder and the like completes the function of auxiliary bending; the power of the device is provided by a movable sliding block and an energy storage oil cylinder of the bending machine, an electric appliance control system is not required to be configured, and the problem of processing multi-angle bend bending cannot be solved.

The specification with the publication number of CN 213256437U discloses a steel pipe bending machine, which comprises a supporting platform, an electric cylinder, a driving die and a driven die mechanism, wherein the driven die mechanism and the electric cylinder are fixedly installed on the top surface of the supporting platform, the driving die is fixedly installed at the piston end of the electric cylinder, a supporting frame is fixedly installed on the top surface of the supporting platform, a guide rail is manufactured on the top surface of the supporting frame, a sliding block is connected on the guide rail in a sliding mode, the sliding block is connected with a gap adjusting handle through a lead screw, an upper connecting plate and a lower connecting plate are integrally manufactured at one end of the sliding block, the upper connecting plate is hinged and connected with two upper-layer wing plates through two upper rotating shafts, the lower connecting plate is hinged and connected with two lower-layer wing plates through two lower rotating shafts, a guide roller is installed between the upper-layer wing plates and the lower-layer wing plates through a positioning pin, an arc-shaped bar hole is respectively manufactured on each upper-layer wing plate, and an angle adjuster is installed between the two arc-shaped bar holes. The steel pipe bending machine bends steel pipes of different specifications and models through the clearance adjusting handle.

Disclosure of Invention

The invention aims to provide a stainless steel bending machine which is simple in structure and easy to operate, solves the problems of high cost and complex operation of bending and forming of an elbow with a special-shaped structure, and realizes the manufacturing of elbows with fixed angles of 90 degrees and variable angles of 0-180 degrees in two directions.

A stainless steel bending machine comprises a base plate, a fixed die fixing assembly fixed on the base plate, and a fixed die assembly fixed above the fixed die fixing assembly;

a circular through hole for fixing a straight steel pipe and a 90-degree elbow through hole for fixing a 90-degree fixed-angle elbow are formed in the fixed die assembly, the diameters of the circular through hole and the 90-degree elbow through hole are the same, and the circular through hole and the 90-degree elbow through hole share one output port;

an R angle die for bending and guiding is arranged on one side of the output port of the fixed die assembly, an R angle die arc groove is formed in the R angle die, and the axis of the R angle die arc groove is connected with and coplanar with the axis of the output port;

a rotating shaft is also vertically fixed on the bottom plate; the rotating shaft is connected with a gear rack mechanism through a bearing; the rack on the gear rack mechanism is connected with a driving assembly, a movable die is arranged above a gear on the gear rack mechanism, one side of the movable die is provided with a movable die arc groove, the axis of the movable die arc groove and the axis of the R angle die arc groove are collinear, and the driving assembly is provided with a displacement sensor and a control system.

A movable die is arranged above the gear, a movable die arc groove is formed in one side of the movable die, and the axis of the movable die arc groove is collinear with the axis of the R angle die arc groove.

The straight steel pipe or the 90-degree elbow steel pipe which needs to be bent is fixed in the fixed die assembly, the part which needs to be bent is arranged in the R angle die arc groove and the movable die arc groove, the rack is driven by the driving assembly to do linear motion, and then the movable die connected to the gear rotates along the R angle die, so that the steel pipe bending parts fixed in the R angle die arc groove and the movable die arc groove are simultaneously bent, and the needed elbow part is obtained.

The fixed die assembly comprises a first fixed die and a second fixed die which are separated along the axial direction of the circular through hole and the 90-degree elbow through hole, the first fixed die is matched with the second fixed die, and the first fixed die and the second fixed die are positioned through the inserting plate and the positioning pin.

The fixed die fixing assembly comprises a fixed die fixing column the bottom of which is welded on the bottom plate and a fixed die bottom plate welded above the fixed die fixing column; the fixed die assembly and the R angle die are fixed on the fixed die base plate through bolts. The fixed die fixing column supports the fixed die base plate, so that the bending machine is compact in structure, and the fixed die assembly and the R angle die are convenient to replace.

The upper portion of gear is equipped with the boss that is used for connecting, boss department has the movable mould bottom plate through bolted connection, movable mould bottom plate and movable mould bolted connection connect the movable mould bottom plate through the boss, can effectively reduce the diameter of gear, improve rack and pinion mechanism's work efficiency, connect gear and movable mould through the movable mould bottom plate simultaneously and make things convenient for the maintenance of gear and the change of movable mould.

Preferably, the arc groove of the R-angle die and the arc groove of the movable die are semicircular grooves. The arc groove of the R-angle die is matched with the arc groove of the movable die, so that the stress of the steel pipe during bending is more reasonable.

Preferably, the driving assembly comprises a hydraulic oil cylinder, the displacement sensor is arranged in the hydraulic oil cylinder, and due to the fact that the hydraulic oil cylinder is simple in structure and reliable in work, when the hydraulic oil cylinder drives the rack to do linear reciprocating motion, a speed reducer can be omitted, a transmission gap is omitted, and the stability of rack motion is guaranteed.

The invention also provides a bending method based on the stainless steel bending machine, and the method solves the problems of bend distortion, fold and tension crack in the manual bend manufacturing process.

A bending method based on the stainless steel bending machine comprises the following steps:

(1) calculating the minimum bending radius of the steel pipe to be bent;

(2) calculating the minimum bending force of the steel pipe, and verifying the thrust of the driving assembly;

(3) verifying the stroke of the driving assembly through the matching movement distance of the rack and the gear;

(4) selecting a matched fixed die assembly and a matched movable die according to the specification of a steel pipe to be bent; selecting a matched R angle die according to the bending R angle of the steel pipe to be bent;

(5) the control system drives the driving assembly to operate, the movable die is located at the position where the axis of the arc groove is collinear with the axis of the output port, the position is set to be an original position through the position sensor, the specification parameters of the rack and pinion mechanism and the angle of the steel pipe to be bent are input into the control system of the driving assembly, the control system sets the operation distance of the rack through the position sensor, and the control system drives the driving assembly to operate to the distance set by the position sensor.

In the step (2), the concrete steps of calculating the minimum bending force of the steel pipe and verifying the thrust of the driving assembly are as follows:

(2-1) calculating the bending moment of the steel pipe through the generalized Huke's law:

M＝σ·W

σ＝E·ε

W＝π(D⁴-d⁴)/16D

wherein σ is the normal stress on the radial section of the steel pipe, W is the section modulus (annular section resisting moment) of the radial section of the steel pipe, M is the bending moment of the steel pipe, E is the elastic modulus of the steel pipe, ε is the axial line strain of the steel pipe, D is the outer diameter of the steel pipe, and D is the inner diameter of the steel pipe;

(2-2) calculating the minimum bending force of the steel pipe according to the simply supported beam model:

F＝4M/L

L＝6R+3D

wherein R is the minimum bending radius of the steel pipe, F is the minimum bending force, and L is the span of the simply supported beam;

(2-3) verifying that the thrust of the driving assembly needs to meet the following requirements according to the minimum bending force of the steel pipe obtained in the step (2-2):

F′＞F/η

wherein, F' is the thrust of the driving assembly, and eta is the actual working efficiency of the driving assembly.

In the step (3), the matching movement distance between the rack and the gear is as follows:

l＝π×d₁×180°/360°

d₁＝mz

wherein d is₁The diameter of a reference circle, m is the gear module, and z is the number of teeth of a gear;

the stroke of the drive assembly needs to satisfy: l₁≥l+l′

Wherein l₁For the working stroke of the driving assembly, l' is reserved for safety.

Compared with the prior art, the invention has the advantages that:

1. according to the invention, through the design of the die, the elbow always keeps on a plane when deformed, so that the problems of distortion, wrinkles, tension cracks and the like easily occurring in the manual manufacturing process of the elbow are avoided.

2. The invention not only realizes the manufacture of the elbow with 0-180 degrees and single angle, but also realizes 2 directions through the design of the fixed die component: manufacturing a 90-degree fixed angle and 0-180-degree variable angle elbow; the hidden troubles caused by casting elbows, connection of a plurality of elbows, welding connection and the like are avoided, and the service performance and the attractiveness of the elbows are improved.

3. The invention controls the linear reciprocating motion stroke of the rack through the displacement sensor, and effectively ensures the angle-variable angle of the elbow.

Drawings

Fig. 1 is a schematic structural diagram of a stainless steel bending machine in an embodiment of the invention.

Fig. 2 is a schematic top view of the stainless steel bending machine shown in fig. 1.

Fig. 3 is a schematic diagram of an original position of the movable die when the stainless steel bending machine bends the straight steel pipe in the embodiment of the invention.

Fig. 4 is a schematic diagram of an original position of a hydraulic cylinder when a stainless steel bending machine bends a straight steel pipe in the embodiment of the invention.

Fig. 5 is a schematic view of a 90-degree bending position of the movable die when the stainless steel bending machine bends the straight steel pipe in the embodiment of the invention.

Fig. 6 is a schematic view of a 90-degree bending position of a hydraulic oil cylinder when a stainless steel bending machine bends a straight steel pipe in the embodiment of the invention.

FIG. 7 is a schematic structural diagram of a straight steel pipe positioned in a fixed die assembly and a moving die in the embodiment of the invention.

Fig. 8 is a schematic position diagram of a stainless steel bending machine for forming a 90 ° fixed-angle elbow with a variable angle of 0 ° in the embodiment of the invention.

Fig. 9 is a schematic position diagram of a stainless steel bending machine for forming a 90 ° fixed-angle elbow with a variable angle of 30 ° in the embodiment of the invention.

Fig. 10 is a schematic position diagram of a stainless steel bending machine for forming a 90 ° fixed-angle elbow with a variable angle of 90 ° in the embodiment of the invention.

Fig. 11 is a schematic position diagram of a stainless steel bending machine for forming a 90 ° fixed-angle elbow with a variable angle of 180 ° in the embodiment of the present invention.

FIG. 12 is a schematic view of a 90 ° fixed angle elbow located in the stationary mold assembly and the moving mold in an embodiment of the present invention.

Detailed Description

As shown in fig. 1 and 2, the stainless steel bending machine comprises a base plate 1 and a fixed die fixing component 2 fixed on the base plate 1, wherein the fixed die fixing component 2 is provided with a fixed die fixing column 21 welded at the bottom of the base plate 1 and a fixed die base plate 22 welded above the fixed die fixing column 21.

The fixed die component 3 is fixed above the fixed die bottom plate 22 through bolts,

the fixed die component 3 is internally provided with a round through hole 15 for fixing the straight steel pipe 13 and a 90-degree elbow through hole 16 for fixing the 90-degree fixed angle elbow 14, the diameter of the round through hole 15 is the same as that of the 90-degree elbow through hole 16, and the round through hole 15 and the 90-degree elbow through hole share one output port 17.

The fixed die assembly 3 comprises a first fixed die 31 and a second fixed die 32 which are separated along the axial direction of the circular through hole 15 and the 90-degree elbow through hole 16, the first fixed die 31 and the second fixed die 32 are symmetrical left and right with the axis of the circular through hole 15 and the 90-degree elbow through hole 16 and are matched with each other, and the first fixed die 31 and the second fixed die 32 are fixed through an inserting plate 33 and a positioning pin 34.

And an R angle die 4 for bending and guiding is arranged on one side of the output port of the fixed die assembly 3, an R angle die arc groove 19 is formed in the R angle die 4, and the axis of the R angle die arc groove 19 is connected with the axis of the output port 17 and is coplanar.

The bottom plate 1 is also fixed with a rotating shaft 5, the axis of the rotating shaft 5 is vertical to the surface of the bottom plate 1, the lower part of the rotating shaft 5 is provided with a groove for fixing, and a pressing plate 6 fixed with the bottom plate 1 is arranged in the groove. The rotation shaft 5 is fixed to the base plate 1 while preventing the rotation shaft 5 from rotating.

The rotating shaft 5 is connected with a gear rack mechanism through a bearing 7, wherein a rack 8 of the gear rack mechanism is fixed at the output end of the driving assembly through a positioning pin, the driving assembly comprises a hydraulic oil cylinder 9 and a control system, a displacement sensor is arranged in the hydraulic oil cylinder 9, the hydraulic oil cylinder 9 is simple in structure and reliable in work, when the hydraulic oil cylinder 9 drives the rack 8 to do linear reciprocating motion, a speed reducer can be omitted, a transmission gap is not formed, and the moving stability of the rack 8 is guaranteed.

The upper portion of gear 10 of rack and pinion mechanism is equipped with the boss that is used for connecting, and boss department has movable mould bottom plate 11 through the bolt fastening, and the bolt fastening has movable mould 12 above movable mould bottom plate 11, connects movable mould bottom plate 11 through the boss, can effectively reduce the diameter of gear 10, improves rack and pinion mechanism's work efficiency, connects gear 10 and movable mould 12 through movable mould bottom plate 11 simultaneously, makes things convenient for the maintenance of gear 10 and the change of movable mould.

One side of the movable mold 12 is provided with a movable mold arc groove 18, and the axis of the movable mold arc groove 18 is collinear with the axis of the R-angle mold arc groove 19.

The R angle die arc groove 19 and the movable die arc groove 18 are semicircular grooves, and the R angle die arc groove 19 is matched with the movable die arc groove 18, so that when the steel pipe is bent, the bent stress part is attached to the wall of the hole or the wall of the groove, and the stress of the steel pipe is more reasonable.

Fixing a straight steel pipe or a 90-degree elbow steel pipe to be bent between a first fixed die 31 and a second fixed die 32, fixing the straight steel pipe or the 90-degree elbow steel pipe through an inserting plate 33 and a positioning pin 34, placing the part to be bent in an R angle die arc groove 19 and a movable die arc groove 18, driving a hydraulic oil cylinder 9 through a control system to drive a rack 8 to do linear motion, further enabling a movable die 12 connected to a gear 10 to rotate along the R angle die 4, and simultaneously bending the steel pipe bending parts fixed in the R angle die arc groove 19 and the movable die arc groove 18 to obtain the required elbow part.

The bending method based on the stainless steel bending machine comprises the following steps:

(1) calculating the minimum bending radius of the steel pipe to be bent;

(2) calculating the minimum bending force of the steel pipe, and verifying the thrust of the hydraulic oil cylinder 9;

(3) the stroke of the hydraulic oil cylinder 9 is verified through the geometric dimension of the gear rack mechanism;

(4) selecting a matched fixed die assembly 3 and a matched movable die 12 according to the specification of a steel pipe to be bent; selecting a matched R angle die according to the bending R angle of the steel pipe to be bent;

(5) the control system drives the hydraulic oil cylinder 9 to operate, the movable die 12 is located at the position where the axis of the arc groove and the axis of the output port are collinear, the position is set to be an original position through the position sensor, the specification parameters of the rack and pinion mechanism and the angle of the steel pipe to be bent are input into the control system, the control system sets the operation distance of the rack 8 through the position sensor, and the control system drives the hydraulic oil cylinder 9 to operate to the distance set by the position sensor.

Taking a steel pipe with the diameter of 40 multiplied by 4.0 as an example, the bending method of the stainless steel bending machine is as follows:

in the step (1), calculating the minimum bending radius of the steel pipe to be bent, and specifically comprising the following steps:

the pipe cold bend radius is specified according to standard JB/T5000.11-1998 as:

when D is less than or equal to 42mm, R' is more than or equal to 2.5D

Wherein, R 'is the cold bending radius, D is the outer diameter of the steel pipe, and R' is not less than 2.5 multiplied by 40 which is 100 mm.

According to the minimum bending radius table of the pipe in the mechanical design manual 1-4-81, the diameter of the stainless seamless steel pipe is 38mm, and when the wall thickness is 3mm, the minimum bending radius is more than or equal to 80 mm; the minimum bending radius of the stainless seamless steel pipe is more than or equal to 100mm when the diameter of the stainless seamless steel pipe is 41mm and the wall thickness of the stainless seamless steel pipe is 3 mm.

According to the two methods for calculating the minimum bending radius of the stainless steel, the minimum bending radius of the steel pipe is taken as R110 mm

In the step (2), the concrete steps of calculating the minimum bending force of the steel pipe and verifying the thrust of the driving assembly are as follows:

(2-1) bending test method of metallic material according to GB-T232-:

the distance between the rollers is L' ═ 2R +3D + -D/2

Calculating L' as 320-

Calculating the bending moment of the steel pipe according to the generalized Huke law:

M＝σ·W

σ＝E·ε

W＝π(D⁴-d⁴)/16D

wherein σ is the normal stress on the radial section of the steel pipe, W is the section modulus (annular section resisting moment) of the radial section of the steel pipe, M is the bending moment of the steel pipe, E is the elastic modulus of the steel pipe, E is 200GPa, E is the axial line strain of the steel pipe, and d is the inner diameter of the steel pipe;

calculated M is 889.9 n.m.

(2-2) calculating the minimum bending force of the steel pipe according to the simply supported beam model:

F＝4M/L

L＝6R+3D

wherein R is the minimum bending radius of the steel pipe, F is the minimum bending force, and L is the span of the simply supported beam;

calculated F-4.5 KN.

(2-3) the specification of the hydraulic oil cylinder 9 is as follows: the cylinder diameter is phi 80mm, the diameter of the piston rod is phi 40mm, the working pressure is 15Mpa, and the using pressure is 67% of the working pressure;

the thrust of the hydraulic oil cylinder 9 is as follows:

wherein P is the working pressure, D_{Activity device}The diameter of the piston rod;

according to the minimum bending force of the steel pipe obtained in the step (2-2), the thrust of the hydraulic oil cylinder 9 needs to meet the following requirements:

F′＞F/η

wherein, F' is the thrust of the hydraulic oil cylinder 9, η is the actual working efficiency of the hydraulic oil cylinder 9, and η is 65%;

the thrust of the hydraulic oil cylinder 9 is larger than the minimum bending force of the steel pipe through calculation and verification; as the return stroke of the hydraulic oil cylinder 9 has no bending acting force, the tension of the hydraulic oil cylinder 9 does not need to be verified.

In the step (3), the matching movement distance of the rack and the gear is as follows:

l＝π×d₁×180°/360°

d₁＝mz

wherein s is₁For the pitch circle diameter, m is the gear module m is 6mm, and z is the gear tooth number z is 60.

Considering the safety reservation, the full tooth length L of the rack is taken₁500 mm; considering the stroke of hydraulic cylinder 9The stroke of the hydraulic oil cylinder 9 needs to be larger than 550 mm.

In the step (4), the matched fixed die component 3 and the matched movable die 12 are selected according to the phi 40 multiplied by 4.0 steel pipe; selecting a matched R angle die according to the bending R angle of the steel pipe to be bent;

(5) the control system drives the hydraulic oil cylinder 9 to operate, the movable die 12 is located at the position where the axis of the arc groove and the axis of the output port are collinear, the position is set to be an original position through the position sensor, the specification parameters of the rack and pinion mechanism and the angle of the steel pipe to be bent are input into the control system, the control system sets the operation distance of the rack 8 through the position sensor, and the control system drives the hydraulic oil cylinder 9 to operate to the distance set by the position sensor.

As shown in fig. 3 to 6, when the movable die is bent by 90 ° at a constant angle, the positions of the movable die and the corresponding rack-and-pinion mechanism change. Fixing the straight steel pipe 13 in the first fixed mold 31 and the second fixed mold 32, as shown in fig. 7; when the movable die assembly is at the original position, a piston of the hydraulic oil cylinder 9 is in a contraction state, and the corresponding movable die 12 is abutted against the fixed die assembly 3; when the steel pipe is bent to 90 degrees, the piston of the hydraulic oil cylinder 9 is in an extending state, and the movable die 12 rotates 90 degrees around the R-angle die 4 relative to the fixed die assembly 3.

As shown in fig. 8 to 11, when the angle is changed by a predetermined angle after the angle is changed by 90 ° and then the movable mold is bent by a predetermined angle, the position of the movable mold is changed, and the 90 ° fixed angle elbow 14 is fixed in the first fixed mold 31 and the second fixed mold 32, and when the angle is changed by 0 °, 30 °, 90 °, and 180 ° after the angle is changed by the further bending, as shown in fig. 12, the movable mold 12 is rotated about the R angle mold 4 with respect to the fixed mold assembly 3 by 0 °, 30 °, 90 °, and 180 ° in this order.