JP5052978B2 - Method for manufacturing a bending roll - Google Patents

Description

  The present invention relates to a method for manufacturing a bending roll used for continuously bending a steel sheet in a pipe making process of an ERW steel pipe, and in particular, the curvature radius R continuously changes from the roll end. The present invention relates to a method for manufacturing a bending roll that has a roll caliber shape and can be used for manufacturing various sizes of ERW steel pipes by changing the inclination angle.

  In the process of manufacturing an electric resistance welded steel pipe, an electric resistance welded steel pipe is manufactured by gradually bending a steel sheet with a multi-stage forming roll and finally forming it into a circular shape, and then performing electric resistance welding between the end faces. This bending process is roughly divided into a first half breakdown process and a second half fin pass process. In particular, a large bending process is performed in the breakdown process.

  In these bending forming steps, forming stands composed of an upper roll and a lower roll for sandwiching a steel plate from above and below are provided in multiple stages. As shown in FIG. 1, a conventional molding stand is a combination of a lower roll having a concave shape corresponding to a desired bending shape and an upper roll having a convex shape smaller than the concave shape by a thickness. These rolls were large rolls corresponding to the entire width of the steel sheet.

  However, in the conventional forming roll as shown in FIG. 1, when the plate thickness of the steel plate is thinner than the design plate thickness, the steel plate and the forming roll are in contact with each other only at the apex portion. There was a problem that molding could not be performed. In addition, since the upper and lower roll shapes are constant, even if the strength and elasticity change depending on the steel plate material, the shape is always the same. For this reason, there existed a problem that the bending shaping | molding which considered spring back etc. could not be performed. Therefore, conventionally, in order to solve the above-mentioned problem, it must be replaced with another forming roll, which requires much cost and time.

  Therefore, as shown in Patent Documents 1 to 3, a roll caliber shape including a required curved surface of each roll flower when bending various outer diameter steel pipes is given to the forming roll, and the roll angle is controlled. A technique for changing the bending R by changing the contact position between the roll and the steel sheet is developed. In these inventions of Patent Documents 1 to 3, a roll caliber shape whose curvature radius R continuously changes, for example, an involute shape is used.

  However, these Patent Documents 1 to 3 only describe “a roll caliber shape including a curved surface of each required part of each roll flower when performing bending forming”. Details on whether to change the radius R are not disclosed. It is also unclear how the minimum and maximum bending radii should be set. In addition, when the roll radius of curvature R is continuously changed, only the specific portion of the roll caliber shape exactly matches the target bend R, and the roll radius of curvature R is always present on both sides thereof. An excessively small portion and a portion having an excessively large radius of curvature R of the roll are generated. For this reason, it is important which position on the caliber should be the bending start position, but this point is also unclear. It is also unclear how the lower roll angle should be set.

  As described above, Patent Documents 1 to 3 show the concept that rolls having a roll caliber shape with a continuously changing radius of curvature R can be used and bending with various curvature radii is possible by changing the angle. However, all the methods for setting the dimensions and angles necessary for producing the optimum roll for the actual process are not disclosed as know-how. For this reason, it is difficult for a user of the facilities disclosed in Patent Documents 1 to 3 to produce or modify a bending roll in accordance with the company's process, and there are many inconveniences.

In addition, since all the patent rights of Patent Documents 1 to 3 are extinguished, it is conceivable to newly manufacture the entire equipment. However, since it is necessary to determine a large number of design values as described above, the optimum value is required. There is a problem that a lot of trial and error is required to reach the production of a bending roll having a thickness of 1.
Japanese Patent Publication No. 3-12975 Japanese Patent Publication No. 3-12976 Japanese Patent Publication No. 3-12977

  Accordingly, an object of the present invention is to provide an optimal bending forming roll that has a roll caliber shape in which the radius of curvature R continuously changes from the roll end, and can be used for manufacturing various sizes of ERW steel pipes by changing the inclination angle. It is an object of the present invention to provide a method of manufacturing a bending roll that can be designed and manufactured without requiring a lot of trial and error in shape.

The present invention made to solve the above-mentioned problems has a roll caliber shape in which the curvature radius R continuously changes from the roll end, and is also used for the production of ERW steel pipes of various sizes by changing the inclination angle. In producing a roll that can
Maximum outer radius R _fe that you want to use as a roll
Minimum thickness _{t fe} at the maximum outer radius _{R fe,}
The minimum outer radius R _fs that you want to use as a roll,
Maximum thickness _{t fs} at the minimum outer radius _{R fs,}
Upper roll angle change range Δθ _ctr ,
Molding ratio α shared by the stand where the roll is installed,
The ratio Kr between the target outer radius at the time of welding and the target outer radius formed by the stand on which the roll is set is set, and these values are set as follows:
Kr (R _fs −t _fs ) = f (θ _fs , θ _bottom )... Equation (1)
Kr ( _{Rfe- tfe} ) = f ([theta] _fe , [theta] _bottom ) (2)
π × (R _fs −t _fs ) × α = ∫R (θ) dθ (the integration range is from θ _fs to θ _fs + θ _bottom ) .. Formula (3)
π × (R _fe −t _fe ) × α = ∫R (θ) dθ (integral range is from θ _fe to θ _fe + θ _bottom ) (4)
R _min = R (θ _fs ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (5)
_Rmax = R ([theta] _fe + [theta] _bottom ) (6)
θ _fe −θ _fs = Δθ _ctr (7)
(Θ _fs is the forming start position when forming a steel pipe with the minimum outer radius and the maximum sheet thickness, and θ _fe is the forming start position when forming the steel pipe with the maximum outer radius and the minimum sheet thickness) To solve the simultaneous equations
Function R (θ) used for roll caliber
Pinch position θ _fs corresponding to minimum outer radius and maximum plate thickness
Pinch position θ _fe corresponding to maximum outer radius and minimum plate thickness
Appropriate lower roll angle θ _bottom
Caliber's minimum bending radius R _min
Caliber's maximum bending radius R _max
And rolls are produced according to these values.

  It is preferable to select a function including one unknown or a function including two unknowns as the function R (θ) used for the roll caliber.

According to the present invention, if the function R (θ) used for the roll caliber contains two or less unknowns, the maximum outer radius R _fe that the designer wants to use as the roll, the minimum thickness t _{fe at} the maximum outer radius Rfe, the roll minimum outer radius R _fs to be a combined _minimum outer radius maximum thickness t _fs in R _fs, angle change range of upper roll theta _ctr, molding ratio alpha, the target outer radius at the time of welding stand the roll is installed to share And the ratio Kr to the target outer radius to be molded by the stand where the roll is installed, it is necessary to solve the equations (1) to (7) as simultaneous equations, and the design necessary for the specific design function used in the value roll caliber R (theta), suitable lower roll angle theta _bottom, minimum bending radius _{R min} of the caliber, obtaining such immediately maximum bending radius _{R max} of the caliber Door can be.

 For this reason, the roll for bending which is the most suitable for the target bending can be manufactured, without repeating trial and error like the past.

  If a function including two or less unknowns is selected as the roll caliber function R (θ) as in claims 2 and 3, all design values including this unknown can be determined simply by solving simultaneous equations.

  The present invention will be described in detail below. First, a forming stand on which a bending roll manufactured according to the present invention is installed will be described. FIG. 2 is a sectional view showing the molding stand. The position of the forming stand is not particularly limited, but here it is arranged at the beginning of the breakdown process in the bending process of the electric resistance welded steel pipe. The forming stand at this position has a role of applying an initial bend to both ends of the flat steel plate.

  In FIG. 2, reference numeral 1 denotes an upper roll which is a bending roll manufactured according to the present invention, and 2 denotes a lower roll, which are arranged at symmetrical positions. Reference numeral 3 denotes a center roll for supporting the central portion, which is disposed in the central portion of the lower rolls 2 and 2. The upper roll 1 and the lower roll 2 are bent and formed along the caliber of the upper roll 1 by sandwiching both ends of the steel plate 10 to be bent. The center support center roll 3 is a roll having a substantially arc-shaped cross-section, and is fixed in position to support the center of the steel plate 10, but the upper roll 1 and the lower roll 2 are in the width direction of the steel plate 10. It is possible to bend the steel plate 10 of various sizes. The upper roll 1 has a structure in which the position used for bending can be changed by inclining the rotation axis as indicated by an arrow. By changing the inclination angle of the upper roll 1 and moving the lower roll 2, it is possible to perform bending with various curvatures.

As shown in FIG. 3, the bending roll is formed into the upper roll 1 by three-point bending in which the upper roll 1 pushes down the vicinity of the end of the steel plate 10 supported by the lower roll 2 and the center support center roll 3. Bending is performed by deforming the steel plate to follow it. According to this method, there is an advantage that the formable range does not become extremely small even if the plate thickness of the steel plate 10 changes greatly.
The variables and functions used in the present invention will be described below.

The upper roll 1 manufactured by the present invention is a forming roll whose curvature continuously changes with the distance along the roll caliber from the roll end. In the present invention, as shown in FIG. 4, the roll caliber shape is represented by a function R (θ) with the angle θ in the tangential direction of the roll as a variable. Since R (θ) changes monotonously with respect to θ, θ and R (θ) correspond one-to-one. Various functions can be used as the function R (θ). A function having a single unknown, for example, R (θ) = R _b θ (R _b is an unknown constant), or a function having two unknowns. For example, R (θ) = Ce ^kθ (C and k are unknown constants) can be used.

FIG. 5 is an explanatory diagram of various variables used in the present invention. First, an angle change range of the upper roll 1 is set to Δθ _ctr . This value is determined by equipment specifications. The minimum bending radius of the caliber is represented by R _min , and the maximum bending radius of the caliber is represented by R _max . The lower roll 2 has a truncated cone shape, and its rotation axis is always constant (horizontal). The angle from the horizontal direction of the surface of the lower roll 2 is _defined as θ _bottom . End position bending the bending start position represented by theta _p is represented by θ _p + θ _bottom.

The above-mentioned function R (θ), lower roll angle θ _bottom , caliber minimum bending radius R _min , caliber maximum bending radius R _max , and bending start position θ _p are indispensable elements for actually designing the roll. However, conventionally, these determination methods have not been disclosed. The present invention intends to determine these values by solving the simultaneous equations of Equations (1) to (7). Prior to that, the target bending conditions are quantified and Equations (1) to (1) to (3) are obtained. Substitute into equation (7).

The bending conditions are as follows:
-Target outer diameter R ₀ to be molded, target plate thickness t ₀ ,
・ Maximum outer radius R _fe to be used as a roll
Minimum thickness _{t fe} at the maximum outer radius _{R fe} ·,
・ Minimum outer radius R _fs to be used as a roll
The maximum thickness _{tfs at the} minimum outer radius _Rfs ,
_-Angle change range Δθ _{ctr of} the upper roll,
・ Molding ratio α shared by the stand where the roll is installed,
Each value of the ratio Kr between the target outer radius during welding and the target outer radius formed by the stand on which the roll is installed. These values are values determined by desired design conditions or facility specifications, and can be easily set by the designer.
Next, equations (1) to (7) for substituting these numerical values will be described.

  Derivation of Equation (1) and Equation (2) will be described below. In a caliber that continuously changes as in the present invention, the radius of curvature R also changes within the bending range as shown in FIG. On the other hand, finally, it must be formed into a circular cross section of the target R before welding. Formula (1) and Formula (2) can be derived by determining which point on the caliber should be the bending start position for this target R.

Now, the target outer radius is R ₀ , the plate thickness is t ₀ , and the corresponding pinch position is θ _p . At this time, the outer radius R aimed at the stand to be designed is KrR ₀ . On the other hand, since the inside of the tube is molded according to the roll, the inside radius needs to be KrR ₀ -t ₀ . The designer needs to give how much the pinch position corresponding to the target inner radius KrR ₀ -t ₀ should be. Now, assuming that the corresponding pinch position is θ _p , the range in which the plate is wound is in the range of θ _p to θ _p + θ _bottom on the roll, so that f (θ _{p in} a general form as a function of θ _p and θ _bottom , if the designer gives theta _bottom) with the aim of bend radius _KRR 0 -t ₀ and f (θ _p, θ _bottom) is _Kr (R 0 _-t 0 and can be connected by equal) = f (θ _p , _θbottom ) can be derived. Since this always holds within the shared range, in the case of both R ₀ = R _fe, t ₀ = t _fe, θ _p = θ _fe and R ₀ = R _fs, t ₀ = t _fs, θ _p = θ _fs It became. From this, equations (1) and (2) can be derived.

As an example of f (θ _p , θ _bottom ), as shown in FIG. 7, for example, when a caliber having a linear relationship between the bending R and the position change on the caliber is used, the bending start position θ _Since it is considered that the average of the molding R at _p and the bending end position θ _bottom should be the target molding R,
_{f (θ p, θ bottom)} = {R (θ p) + R (θ p + θ bottom)} / 2 = KrR 0 -t 0
And it is sufficient.

Further, as shown in FIG. 8, the bending length between the R and if the change in the position of the caliber was used caliber such that the relationship of the curve, bending start position theta _p and the bending end position theta _bottom Considering that the average R is the target molding R, the following formula 1 may be adopted.

Equations (3) and (4) are derived as follows.
As shown in FIG. 9, even if the steel plate is pinched and formed at the same position of the roll caliber, the range in which bending is applied varies significantly depending on the angle from the horizontal direction of the center line of the plate thickness at the bending forming start position. In the pipe making process, the bending range per stage is determined to some extent from the number of stands and the like, which is a problem. Expression (2) is an expression showing how to set the bending forming start position θ _p and the plate angle θ _bottom at the bending start position and apply the bending to obtain an appropriate bending range.

As shown in FIG. 10, the steel plate must be circular before welding, and its central angle is 360 °. On the other hand, if the forming range necessary for the designed stand is represented by α, the corresponding central angle is θ _ffx and α = θ _ffx / 360, so it is necessary if the plate thickness is t. The one-side molding range length is π × (R ₀ −t ₀ ) × α inside the tube. On the other hand, the molding range length of the inner when the molding start position was theta _p is a caliber shape R (theta) from ∫R (θ) dθ (integration range theta from θ _{p p +} θ _bottom). From the above, the relationship of π × (R ₀ −t ₀ ) × α = ∫R (θ) dθ (the integration range is θ _p to θ _p + θ _bottom ) can be derived. This equation _{applies to} both R ₀ = R _fe, t ₀ = t _fe, θ _p = θ _fe and R ₀ = R _fs, t ₀ = t _fs, θ _p = θ _fs , and from here (3) and equation (4) can be derived.

R _min = R (θ _fs ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (5)
_Rmax = R ([theta] _fe + [theta] _bottom ) (6)
θ _fe −θ _bottom = Δθ _ctr (7)
The above equations (5) to (7) are derived as follows.

These equations show how to design R _max which is the maximum R and R _min which is the minimum R for the outer diameter wall thickness range to be manufactured.
As shown in FIG. 11, even if the end of the steel plate is pinched by the end of the caliber, the forming range cannot be secured. For this reason, the part of the caliber that can be used as the molding start position is limited. In addition, it is necessary to realize the necessary R change within the limit of the roll inclination change width on the equipment. In other words, R _max and R _min of the caliber R can be formed at the caliber part that can be used as the forming start position in consideration of the required forming range, and can be formed with a controllable angular width. Must be designed to be

Now, when the molding start position is θ _p , the molding end position is θ _p + θ _bottom , so R _min = R (θ _fs ) (5) and R _max = R (θ _fe + θ _bottom ) It is necessary to satisfy (6).

In addition, since it is necessary to form a desired combined range within the controllable range of the roll angle, it is necessary to satisfy the equation (7) of θ _fe −θ _bottom = Δθ _ctr .

As described above, the equations (1) to (7) perform various sizes of bending by changing the inclination angle of the roll having a roll caliber shape in which the curvature radius R continuously changes from the roll end. It is a formula that shows the best conditions. Therefore, the maximum outer radius R _fe that the designer wants to _{share with} the roll, the minimum plate thickness t _{fe at} the maximum outer radius R _fe , the minimum outer radius R _fs that he / she wants to _{share with} the roll, and the maximum plate thickness t _{fs at the} minimum outer radius R _fs set by the designer. The angle change range Δθ _ctr of the upper roll, the forming ratio α shared by the stand where the roll is installed, the ratio Kr of the target outer radius during welding and the target outer radius formed by the stand where the roll is installed By substituting into these seven equations and solving the simultaneous equations, the function R (θ) used for the roll caliber, the appropriate lower roll angle θ _bottom , the caliber minimum bending radius R _{min, and the} caliber maximum bending radius R _max are obtained. Can be sought.

The number of equations is seven, but the unknowns are five of θ _bottom , θ _fs , θ _fe , R _min, R _max except for those included in the function R (θ). When θ) includes only two or less unknowns, numerical values necessary for design can be automatically obtained by solving simultaneous equations. In addition, even when the function R (θ) includes three or more unknowns, it is only necessary to find the optimal solution by changing only the third and subsequent unknowns as design variables, and the design can be performed with less trial and error than before. .

  In this way, according to the present invention, it is possible to calculate the specifications necessary for the production of the roll. Therefore, if the roll is manufactured according to the specifications, a roll having the best shape can be obtained with respect to the design value input by the designer. Will be. For this reason, it is not necessary to repeat trial and error as in the prior art, and the manufacturing cost and the manufacturing time can be greatly reduced.

An embodiment will be described in the case where an involute curve with R (θ) = R _b θ (where R _b is an unknown) is used as a function representing the roll caliber. At this time, if it is designed so that the average R within the winding range of the plate is the target forming R, f (θ _p , θ _bottom ) = {R (θ _p ) + R (θ _p + θ _bottom )} / 2 = KrR ₀ -t ₀
From the beginning, equations (1) to (7) can be written as follows.
Kr (R _fs −t _fs ) = R _b (2θ _fs + θ _bottom ) / 2... Formula (1) ′
Kr ( _{Rfe- tfe} ) = _Rb (2 _[ theta] _fe + [theta] _bottom ) / 2... Equation (2) '
π × (R _fs −t _fs ) × α = R _b θ _bottom (2θ _fs + θ _bottom ) / 2... Formula (3) ′
π × (R _fe −t _fe ) × α = R _b θ _bottom (2θ _fe + θ _bottom ) / 2... Formula (4) ′
R _min = R _b θ _fs ........... Formula (5) '
_Rmax = _Rb ([theta] _fe + [theta] _bottom )... Equation (6) '
θ _fe −θ _fs = Δθ _ctr (7) ′

Here, θ _fs is eliminated from the equations (1) ′ and (3) ′, and θ _bottom = πα / Kr (8)
The _{R b} = playing the 'formula (1) from' Equation _{(2) {(R fe -R} fs) - (t fe -t fs)} / (θ fe -θ fs)
Here, θ _fe −θ _fs is eliminated using equation (7) ′, and R _b = {(R _fe −R _fs ) − (t _fe −t _fs )} / Δθ _ctr ... (9)
Substituting Equation (8) and Equation (9) into Equation (1) ′ and Equation (2) ′ for rearrangement, θ _fs = [KrΔθ _ctr (R _fs −t _fs ) / {(R _fe −R _fs ) -(T _fe -t _fs )}]-πα / 2Kr (10)
_{θ fe = [KrΔθ ctr (R} fe -t fe) / {(R fe -R fs) - (t fe -t fs)}] - πα / 2Kr ··· formula (11)
Further, if Expression (8), Expression (10) and Expression (11) are substituted into Expression (5) ′ and Expression (6) ′, R _min = [{(R _fe −R _fs ) − (t _fe −t _{fs )} / Δθ ctr] × [} [KrΔθ ctr (R fs -t fs) / {(R fe -R fs) - (t fe -t fs)}] - πα / 2Kr] ··· formula (12)
_{R max = [{(R fe} -R fs) - (t fe -t fs)} / Δθ ctr] × [[KrΔθ ctr (R fe -t fe) / {(R fe -R fs) - (t fe −t _fs )}] + πα / 2 Kr] (13)
Can be guided.

Here, the maximum outer radius R _fe that the designer wants to _share the roll,
Minimum thickness _{t fe} at the maximum outer radius _{R fe,}
The minimum outer radius R _fs that you want to use as a roll,
Maximum thickness _{t fs} at the minimum outer radius _{R fs,}
Upper roll angle change range Δθ _ctr ,
Molding ratio α shared by the stand where the roll is installed,
If the ratio Kr between the target outer radius at the time of welding and the target outer radius formed by the stand on which the roll is installed is given as a design value, the above formulas (8), (9), ( It can be seen that the values necessary for the design can be automatically calculated from 10), Equation (11), Equation (12), and Equation (13).

It is sectional drawing which shows the conventional shaping | molding stand. It is sectional drawing of the stand for shaping | molding in which the roll manufactured by this invention is installed. It is sectional drawing which shows the mode of bending molding. It is explanatory drawing of a roll caliber shape. It is explanatory drawing of the various variables used by this invention. It is sectional drawing which shows the relationship between the position on a caliber, and the bending R. FIG. It is a graph which shows the relationship between the position on a caliber, and the bending R. It is a graph which shows the relationship between the position on a caliber, and the bending R. It is sectional drawing which shows the relationship between the pinch position of a steel plate, and a bending range. It is explanatory drawing of the shaping | molding range (alpha) required with a stand. It is explanatory drawing of the range which can be used as a shaping | molding start position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper roll 1A, 1B Upper roll axis 2 Lower roll 2A, 2B Lower roll axis 3 Center part support center roll 10 Steel plate

Claims (3)

In producing a roll that has a roll caliber shape in which the curvature radius R continuously changes from the roll end, and can be used for the production of various sizes of ERW steel pipes by changing the inclination angle.
Maximum outer radius R _fe that you want to use as a roll
Minimum thickness _{t fe} at the maximum outer radius _{R fe,}
The minimum outer radius R _fs that you want to use as a roll,
Maximum thickness _{t fs} at the minimum outer radius _{R fs,}
Upper roll angle change range Δθ _ctr ,
Molding ratio α shared by the stand where the roll is installed,
The ratio Kr between the target outer radius at the time of welding and the target outer radius formed by the stand on which the roll is set is set, and these values are set as follows:
Kr (R _fs −t _fs ) = f (θ _fs , θ _bottom )... Equation (1)
Kr ( _{Rfe- tfe} ) = f ([theta] _fe , [theta] _bottom ) (2)
π × (R _fs −t _fs ) × α = ∫R (θ) dθ (the integration range is from θ _fs to θ _fs + θ _bottom ) .. Formula (3)
π × (R _fe −t _fe ) × α = ∫R (θ) dθ (integral range is from θ _fe to θ _fe + θ _bottom ) (4)
R _min = R (θ _fs ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (5)
_Rmax = R ([theta] _fe + [theta] _bottom ) (6)
θ _fe −θ _fs = Δθ _ctr (7)
(Θ _fs is the forming start position when forming a steel pipe with the minimum outer radius and the maximum sheet thickness, and θ _fe is the forming start position when forming the steel pipe with the maximum outer radius and the minimum sheet thickness) To solve the simultaneous equations
Function R (θ) used for roll caliber
Pinch position θ _fs corresponding to minimum outer radius and maximum plate thickness
Pinch position θ _fe corresponding to maximum outer radius and minimum plate thickness
Appropriate lower roll angle θ _bottom
Caliber's minimum bending radius R _min
Caliber's maximum bending radius R _max
And manufacturing a roll according to these values.   2. The method for producing a bending roll according to claim 1, wherein the function R (θ) used for the roll caliber is a function including one unknown.   The method for manufacturing a roll for bending according to claim 1, wherein the function R (θ) used for the roll caliber is a function including two unknowns.