CN112275990A - Pretightening force parameter optimization method for frame of plate-frame type hydraulic machine and frame device - Google Patents

Pretightening force parameter optimization method for frame of plate-frame type hydraulic machine and frame device Download PDF

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CN112275990A
CN112275990A CN202011262548.5A CN202011262548A CN112275990A CN 112275990 A CN112275990 A CN 112275990A CN 202011262548 A CN202011262548 A CN 202011262548A CN 112275990 A CN112275990 A CN 112275990A
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frame
shaped plate
pull rod
tightening
plate frame
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CN112275990B (en
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金淼
吴洋
邹宗园
赵石岩
张庆玲
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Jinan Juneng Cnc Machinery Co ltd
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Yanshan University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J13/00—Details of machines for forging, pressing, or hammering
    • B21J13/04—Frames; Guides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J9/00—Forging presses
    • B21J9/10—Drives for forging presses
    • B21J9/12—Drives for forging presses operated by hydraulic or liquid pressure

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  • Mechanical Engineering (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
  • Presses And Accessory Devices Thereof (AREA)

Abstract

The invention provides a method for optimizing pretightening force parameters of a frame of a plate-and-frame hydraulic machine, which specifically comprises the following steps: determining the pre-tightening force in a frame structure of the plate-and-frame hydraulic machine, firstly analyzing the stress of the O-shaped plate frame, calculating the tension-compression rigidity ratio of the first pull rod and the longitudinal side frame of the O-shaped plate frame, and obtaining the pre-tightening force of the first pull rod and the tension of the first pull rod after bearing according to the deformation balance condition; and determining the specific application position of the pre-tightening force in the frame structure of the plate-and-frame hydraulic machine, and calculating the specific application position of the pre-tightening force on the O-shaped plate frame according to the principle that the deformation of the loaded O-shaped plate frame is minimum. The frame structure realizes the assembly and longitudinal pre-tightening of the hydraulic machine frame structure through the pre-tightening nut, and the resultant force of the applied pre-tightening force is positioned on the inner side of the central line of the longitudinal side frame of the O-shaped plate frame. According to the invention, the longitudinal pre-tightening force is applied to the O-shaped plate frame in the hydraulic machine frame, so that the longitudinal rigidity of the hydraulic machine frame is improved, and the service life of the hydraulic machine is prolonged.

Description

Pretightening force parameter optimization method for frame of plate-frame type hydraulic machine and frame device
Technical Field
The invention relates to the field of hydraulic presses, in particular to a method for optimizing pretightening force parameters of a frame of a plate-frame type hydraulic press and a frame device.
Background
The hydraulic machine is a key device for producing forgings in the forging industry, and with increasingly severe competition of the international equipment manufacturing industry, the manufacturing capability of large forgings is very important, and the manufacturing of the large forgings cannot be separated from the large hydraulic machine. The plate-frame type frame is one of the main structural forms of a large hydraulic machine body, the frame bears huge working load when the hydraulic machine works, and the rigidity and the strength of the frame play an important role in the safety of the whole machine and the quality of a product, so the frame of the large hydraulic machine is usually huge and heavy. On the premise of reducing the weight of the frame of the large hydraulic machine, the effort of improving the strength and rigidity of the frame is always an important development direction of the body structure of the large hydraulic machine.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a pretightening force parameter optimization method and a frame structure for a frame of a plate-and-frame type hydraulic machine.
The invention provides a method for optimizing pretightening force parameters in a frame structure of a plate-and-frame hydraulic machine with pretightening force, which comprises the following steps:
s1, determining the size of the pretightening force in the frame structure of the plate-and-frame hydraulic machine:
s11, analyzing the stress of the O-shaped plate frame according to the actual engineering condition, making a stress and deformation diagram after the O-shaped plate frame is split, and making the compression rebound quantity delta L of the longitudinal side frame of the O-shaped plate frame in the loading process1Re-extension amount DeltaL of first pull rod2Equal, i.e. Δ L1＝ΔL2The specific expression is as follows:
Figure BDA0002775094860000011
Figure BDA0002775094860000021
in the formula, F0The resultant force of the pretightening force of the first pull rod on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod on one side is under the tension when bearing; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the one-sided first pull rods; h1The net height of the side frame of the O-shaped plate frame is the distance between the transverse upper frame and the transverse lower frame of the O-shaped plate frame; h2The effective length of the first pull rod is the distance between the upper and lower pre-tightening nuts of the first pull rod; e is the modulus of elasticity;
s12, calculating the tension-compression rigidity ratio m of the first pull rod and the longitudinal side frame of the O-shaped plate frame, wherein m is the tension-compression rigidity ratio of the first pull rod on the single side of the O-shaped plate frame and the longitudinal side frame, and the calculation expression is as follows:
Figure BDA0002775094860000022
in the formula, m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the one-sided first pull rods; h1The net height of the side frame of the O-shaped plate frame is the distance between the transverse upper frame and the transverse lower frame of the O-shaped plate frame; h2The effective length of the first pull rod is the distance between the upper and lower pre-tightening nuts of the first pull rod;
s13, combining the tension-compression stiffness ratio m obtained in the step S12 with the deformation balance condition of the plate frame type hydraulic machine frame structure in an ideal state to obtain the pretightening force of the first pull rod and the tension applied to the first pull rod after bearing;
in step S13, the specific steps of obtaining the resultant force of the first tie bar pretightening force are as follows:
s131, resulting from steps S11 and S12:
F2-F1＝(1+m)(F0-F1)
in the formula, m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; f0The resultant force of the pretightening force of the first pull rod on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod on one side is under the tension when bearing;
s132, according to the balance condition, under the bearing state of the frame structure of the plate-frame type hydraulic machine, the following expression is shown:
Figure BDA0002775094860000023
under the ideal state, when the frame structure of the plate-frame type hydraulic machine bears the load, the compression resilience amount of the longitudinal side frame is equal to the precompression amount, and the side frame does not bear the stress, namely F1When the ratio is 0, the following:
Figure BDA0002775094860000031
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame;
s133, substituting the formula into the step S131 to obtain an expression of the magnitude of the resultant force of the first pull rod on one side, wherein the expression is as follows:
Figure BDA0002775094860000032
in the formula, F0The resultant force of the pretightening force of the first pull rod on one side; m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame;
s2, determining the specific application position of the pretightening force in the frame structure of the plate-frame type hydraulic machine:
s21, respectively calculating the deformation influence of the actual working load and the tension on the O-shaped plate frame caused by the first pull rod after bearing in the step S13, and introducing an interactive deformation coefficient lambda1、λ2Respectively calculating the corner bending moments of a transverse frame and a lower frame in the O-shaped plate frame, and calculating the deformation of a longitudinal side frame of the O-shaped plate frame by adopting an superposition method, wherein the interactive deformation coefficient expression is as follows:
Figure BDA0002775094860000033
Figure BDA0002775094860000034
in the formula, λ1、λ2The cross deformation coefficients of the transverse frame and the lower frame are obtained; a ═ γ2+2γ(K1+K2)，B＝3K1K2(ii) a Gamma is the ratio of the height H of the vertical side frame of the O-shaped plate frame to the length L of the horizontal upper frame and the horizontal lower frame of the O-shaped plate frame, and gamma is H/L; k1Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame1The ratio of (A) to (B); k2Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame2The ratio of (A) to (B);
in step S21, the specific determination step of the deformation size of the longitudinal side frame of the O-shaped plate frame is as follows:
s211, when the sizes of the upper frame and the lower frame of the O-shaped plate frame are consistent, namely K1＝K2＝K，λ1＝λ2Lambda, simultaneously, when the plate and frame hydraulic press frame only bore operating load, the expression of the corner moment of bending of O type sheet frame is:
Figure BDA0002775094860000041
in the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames(ii) a L is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; lambda is an interactive deformation coefficient;
s212, when the frame of the plate-and-frame hydraulic press bears the load, the first pull rod bears the tension F2The bending moment to the corner of the O-shaped plate frame is as follows:
Figure BDA0002775094860000042
in the formula, M2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; lambda is an interactive deformation coefficient;
s213, combining the steps S211 and S212, under the condition of a given pretightening force, after the O-shaped plate frame bears, the bending moment of the corner is as follows:
M0＝M1+M2
the horizontal deformation of the middle point of the longitudinal side frame is as follows:
Figure BDA0002775094860000043
in the formula, W is the horizontal deformation of the midpoint of the longitudinal side frame of the O-shaped plate frame; m1Bending moment of the working load to the corner of the O-shaped plate frame; m2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; m0Under the given pretightening force, the O-shaped plate frame bears the bending moment of the rear corner; i is the section moment of inertia of the longitudinal side frame of the O-shaped plate frame;
s22, calculating the specific position of the pre-tightening force exerted on the O-shaped plate frame under the condition that the working load, the pre-tightening force and the structural dimension parameters are fixed according to the principle that the deformation of the loaded O-shaped plate frame is minimum, and obtaining the relation between the pre-tightening force position ratio beta and the contact span ratio alpha:
Figure BDA0002775094860000044
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the pre-tightening force position ratio, namely the ratio of the distance between the pre-tightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper frame and the transverse lower frame.
Preferably, in step S22, in an ideal state, the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame is 0, and the specific expression of the horizontal deformation W obtained by the calculation process in step S21 is:
Figure BDA0002775094860000051
according to the specific expression of the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame, M can be known1＝-M2，(3-3α+α2)＝48β2(1-β)2；
In the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame; m2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; h is the height of the vertical side frame of the O-shaped plate frame, namely the distance between the center lines of the horizontal upper frame and the horizontal lower frame.
Preferably, the invention also provides a plate-and-frame hydraulic press frame device which comprises an O-shaped plate frame, a first pull rod, a pre-tightening beam, a pre-tightening nut and a second pull rod; the O-shaped plate frame comprises a front O-shaped plate frame and a rear O-shaped plate frame, the pre-tightening beams comprise a first pre-tightening beam and a second pre-tightening beam, the first pre-tightening beam is positioned at the upper end of the O-shaped plate frame and symmetrically distributed on two sides of the upper end of the O-shaped plate frame, the first end of the first pre-tightening beam is connected with the upper end of the front O-shaped plate frame, the second end of the first pre-tightening beam is connected with the upper end of the rear O-shaped plate frame, the second pre-tightening beam is positioned at the lower end of the O-shaped plate frame and symmetrically distributed on two sides of the lower end of the O-shaped plate frame, the first end of the second pre-tightening beam is connected with the lower end of the front O-shaped plate frame, and the second end of the second pre-tightening; the first end of the first pull rod is connected with the first pre-tightening beam through a pre-tightening nut, the second end of the first pull rod is connected with the second pre-tightening beam through a pre-tightening nut, the first pull rod is distributed in a bilateral symmetry mode in the longitudinal direction of the O-shaped plate frame, the first end of the second pull rod is fixedly connected with the front O-shaped plate frame through a pre-tightening nut, the second end of the second pull rod is fixedly connected with the rear O-shaped plate frame through a pre-tightening nut, the second pull rod is uniformly distributed in the transverse direction of the O-shaped plate frame, the pre-tightening nut achieves assembly and longitudinal pre-tightening of a frame structure of the hydraulic machine, and deformation of the O-shaped plate frame in the stress process is reduced.
Preferably, the pre-tightening beam and the first pull rod are arranged on the inner side of the central line of the longitudinal side frame of the O-shaped plate frame, and the sum of the pre-tightening forces applied by the pull rods is located on the inner side of the central line of the longitudinal side frame of the O-shaped plate frame.
Preferably, the number of the O-shaped plate frames is two or more.
Preferably, each group of O-shaped plate frames is formed by combining a single O-shaped plate or a plurality of O-shaped plates.
Preferably, the pre-tightening beams are distributed in the hydraulic machine frame structure in a vertical or bilateral symmetry manner, one pre-tightening beam or a group of pre-tightening beams is selectively installed at the pre-installation position of the pre-tightening beam according to the working condition of the hydraulic machine frame structure, and the pre-tightening beam and the first pull rod are located in the same plane.
Preferably, the length of the pre-tightening beam is greater than the distance between the front O-shaped plate frame and the rear O-shaped plate frame, the middle part of the pre-tightening beam is located between the front O-shaped plate frame and the rear O-shaped plate frame, and two ends of the pre-tightening beam respectively extend out of the front end of the front O-shaped plate frame and the rear end of the rear O-shaped plate frame.
Compared with the prior art, the invention has the following advantages:
1. on the basis of effectively reducing the structural weight of the frame of the hydraulic machine, longitudinal pre-tightening force is applied to an O-shaped plate frame in the frame of the hydraulic machine, so that the longitudinal rigidity of the frame of the hydraulic machine is improved, an optimization method of pre-tightening force parameters is provided, and the mathematical relationship among the pre-tightening force, the specific applied position, the working load and the frame structural parameters is obtained;
2. compared with the existing plate-frame type hydraulic press frame, the invention reduces the deformation of the O-shaped plate frame, improves the stress size and distribution, improves the production quality of products and prolongs the service life of the hydraulic press.
Drawings
FIG. 1 is a front view of the housing assembly of the present invention;
FIG. 2 is a top view of the housing assembly of the present invention;
FIG. 3 is a simplified stress diagram of an O-shaped plate frame under a working load without applying a longitudinal pre-tightening force in the rack device according to the present invention;
FIG. 4 is a simplified diagram of the deformation of the O-shaped plate frame under the working load without applying a longitudinal pre-tightening force in the rack device according to the present invention;
FIG. 5 is a simplified stress diagram of an O-shaped plate frame under a working load when a longitudinal pre-tightening force is applied to the rack device according to the present invention;
FIG. 6 is a simplified diagram of the deformation of the O-shaped plate frame under the working load when longitudinal pre-tightening force is applied to the rack device according to the present invention;
FIG. 7 is a simplified diagram of the stress and deformation of the split front O-shaped plate frame after applying a longitudinal pre-tightening force and bearing a working load in the rack device according to the present invention;
fig. 8 is a selected drawing of the reference point for deformation of the O-shaped plate frame in the rack device according to the present invention.
The main reference numbers:
the O-shaped plate frame comprises an O-shaped plate frame 1, a front O-shaped plate frame 11, a rear O-shaped plate frame 12, a first pull rod 2, a pre-tightening beam 3, a first pre-tightening beam 31, a second pre-tightening beam 32, a pre-tightening nut 4 and a second pull rod 5.
Detailed Description
The technical contents, structural features, attained objects and effects of the present invention are explained in detail below with reference to the accompanying drawings.
The method for optimizing the pre-tightening force parameter in the frame structure of the plate-and-frame hydraulic machine with the pre-tightening force comprises the following steps under ideal conditions:
s1, determining the size of the pretightening force in the frame structure of the plate-and-frame hydraulic machine:
s11, analyzing the stress of the O-shaped plate frame 1 according to the actual engineering condition, making a simplified stress and deformation diagram after the O-shaped plate frame 1 is split, wherein the compression rebound quantity of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 is very small and can be ignored during bearing, so that the compression rebound quantity delta L of the longitudinal side frame of the O-shaped plate frame 1 is negligible during loading1Re-extension amount DeltaL of first pull rod 22Equal, i.e. Δ L1＝ΔL2The specific expression is as follows:
Figure BDA0002775094860000071
Figure BDA0002775094860000072
in the formula, F0The resultant force of the pretightening force of the first pull rod 2 on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod 2 on one side is under the tension force when bearing; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the single-sided first pull rods 2; h1The net height of the side frame of the O-shaped plate frame 1 is the transverse upper and lower frame interval of the O-shaped plate frame 1; h2The effective length of the first pull rod 2 is the distance between the upper and lower pre-tightening nuts 4 of the first pull rod 2; e is the modulus of elasticity.
S12, calculating the tension-compression stiffness ratio m of the first pull rod 2 and the longitudinal side frame of the O-shaped plate frame 1, wherein m is the tension-compression stiffness ratio of the first pull rod 2 on one side of the O-shaped plate frame 1 and the longitudinal side frame, and the calculation expression is as follows:
Figure BDA0002775094860000073
in the formula, m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the single-sided first pull rods 2; h1The net height of the side frame of the O-shaped plate frame 1 is the transverse upper and lower frame interval of the O-shaped plate frame 1; h2The effective length of the first pull rod 2 is the distance between the upper and lower pretension nuts 4 in the first pull rod 2.
S13, combining the tension-compression stiffness ratio m obtained in the step S12 with the deformation balance condition of the plate frame type hydraulic machine frame structure under an ideal state to obtain the pretightening force of the first pull rod 2 and the tension applied to the first pull rod 2 after bearing;
s131, from steps S11 and S12, it is possible to:
F2-F1＝(1+m)(F0-F1)
in the formula, m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; f0Is the resultant of the pretension force of the one-sided first pull rod 2, FPreparation of＝4×F0；F1The side frame bears axial pressure when bearing; f2Is the tension force to which the first pull rod 2 on one side is subjected when bearing load.
S132, according to the balance condition, under the bearing state of the frame structure of the plate-frame type hydraulic machine, the following expression is shown:
Figure BDA0002775094860000081
under the ideal state, when the frame structure of the plate-frame type hydraulic machine bears the load, the compression resilience amount of the longitudinal side frame is equal to the precompression amount, and the side frame does not bear the stress, namely F1When the ratio is 0, the following:
Figure BDA0002775094860000082
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame 1; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; and q is the unit length bearing pressure of the upper frame and the lower frame.
S133, substituting the above formula into step S131, an expression of the magnitude of the resultant pre-tightening force of the one-side first pull rod 2 can be obtained:
Figure BDA0002775094860000083
in the formula, F0The resultant force of the pretightening force of the first pull rod 2 on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod 2 on one side is under the tension force when bearing; m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames in the O-shaped plate frame 1; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; and q is the unit length bearing pressure of the upper frame and the lower frame.
S2, determining the specific application position of the pretightening force in the frame structure of the plate-frame type hydraulic machine:
s21, respectively calculating the deformation influence of the actual working load and the tension on the O-shaped plate frame 1 caused by the first pull rod 2 after bearing in the step S13, and introducing an interactive deformation coefficient lambda1、λ2Respectively calculating the corner bending moments of the transverse side frame and the lower side frame of the O-shaped plate frame 1, and calculating the deformation of the longitudinal side frame of the O-shaped plate frame 1 by adopting an superposition method, wherein the interactive deformation coefficient expression is as follows:
Figure BDA0002775094860000091
Figure BDA0002775094860000092
in the formula, λ1、λ2The cross deformation coefficients of the transverse frame and the lower frame are obtained; a ═ γ2+2γ(K1+K2)，B＝3K1K2(ii) a Gamma is the height H of the longitudinal side frame of the O-shaped plate frame 1 and the length of the transverse upper and lower frames of the O-shaped plate frame 1The ratio of the degree L, γ ═ H/L; k1Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame1The ratio of (A) to (B); k2Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame2The ratio of (A) to (B); l is the length of the transverse upper and lower frames of the O-shaped plate frame 1; h is the height of the longitudinal side frame of the O-shaped plate frame 1, namely the distance between the center lines of the transverse upper frame and the transverse lower frame.
S211, when the sizes of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 are consistent, namely K1＝K2＝K，λ1＝λ2Lambda, when the plate and frame hydraulic press frame only bears the working load simultaneously, the expression of the corner bending moment of the O-shaped plate frame 1 is:
Figure BDA0002775094860000093
in the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame 1; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; and lambda is an interactive deformation coefficient.
S212, when the frame of the plate-and-frame hydraulic press bears the load, the first pull rod 2 bears the tension F2The bending moment to the corner of the O-shaped plate frame 1 is as follows:
Figure BDA0002775094860000094
in the formula, M2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame 1; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; and lambda is an interactive deformation coefficient.
S213, combining the steps S211 and S212, under the condition of a given pretightening force, after the O-shaped plate frame 1 bears, the bending moment of the corner is as follows:
M0＝M1+M2
the horizontal deformation of the middle point of the longitudinal side frame is as follows:
Figure BDA0002775094860000101
in the formula, W is the horizontal deformation of the midpoint of the longitudinal side frame of the O-shaped plate frame 1; m1Bending moment of the working load to the corner of the O-shaped plate frame 1; m2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame 1; m0Under the given pretightening force, the O-shaped plate frame 1 bears the bending moment of the rear corner; i is the section moment of inertia of the longitudinal side frame of the O-shaped plate frame 1.
S22, calculating the specific position of the pre-tightening force exerted on the O-shaped plate frame 1 under the condition that the working load, the pre-tightening force and the structural dimension parameters are fixed according to the principle that the deformation of the O-shaped plate frame 1 after bearing is minimum, and obtaining the relation between the pre-tightening force position ratio beta and the contact span ratio alpha:
Figure BDA0002775094860000102
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the pre-tightening force position ratio, namely the ratio of the distance between the pre-tightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper frame and the transverse lower frame.
Further, in an ideal state, the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame 1 is equal to 0, and the specific expression of the horizontal deformation W obtained by the calculation process in step S21 is as follows:
Figure BDA0002775094860000103
according to the specific expression of the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame 1, M can be known1＝-M2，(3-3α+α2)＝48β2(1-β)2；
In the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame 1; m2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame 1; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; h is the height of the longitudinal side frame of the O-shaped plate frame 1, namely the distance between the center lines of the transverse upper frame and the transverse lower frame.
As shown in figures 3 and 4, under the condition that longitudinal pre-tightening force is not applied to the frame of the plate-frame type hydraulic machine, when the frame of the plate-frame type hydraulic machine bears working load, the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 bear the working load FLoad(s)Bearing a working load FLoad(s)Transmitted to the longitudinal side frames of the O-shaped plate frame 1 and reflected as tensile forces F towards the two ends of the longitudinal side framesPulling deviceCausing the longitudinal side frames of the O-shaped plate frame to elongate; under working load FLoad(s)The transverse upper and lower frames of the O-shaped plate frame 1 can generate outward bending deformation, the bending moment transmitted by the bending deformation causes the longitudinal side frames to bend inward, and the overall deformation of the O-shaped plate frame 1 is severe.
As shown in fig. 5 and 6, a longitudinal pretightening force F is applied to the O-shaped plate frame 1 through the first pull rod 2, the pretightening beam 3 and the pretightening nut 4Preparation of，FPreparation ofIs transmitted to the longitudinal side frame of the O-shaped plate frame 1 and is reflected as a pressure F towards the middlePress and pressAnd because the first pull rod 2 and the pre-tightening beam 3 are positioned on the inner side of the central line of the longitudinal side frame of the O-shaped plate frame 1, the pressure F on the longitudinal side framePress and pressAlso inboard of the longitudinal side frame centerline. When not bearing the working load, the longitudinal side frame of the O-shaped plate frame 1 has a certain pre-compression amount and outward bending deformation. Under the condition of applying longitudinal pretightening force, when the frame of the plate-frame type hydraulic machine bears working load, the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 bear the working load F simultaneouslyLoad(s)And a pre-tightening force FPreparation ofAt a working load FLoad(s)Under the action of (1), the pre-compression amount and the outward bending deformation of the longitudinal side frame of the O-shaped plate frame 1 gradually increaseThe first pull rod 2 and the O-shaped plate frame 1 bear the working load F at the same timeLoad(s)The deformation of the O-shaped plate frame 1 when the plate-frame type hydraulic machine frame works is reduced, and the size and the distribution of stress in the plate-frame type hydraulic machine frame are improved.
The frame structure of the plate-frame type hydraulic machine with pretension is shown in fig. 1 and fig. 2, and comprises an O-shaped plate frame 1, a first pull rod 2, a pretension beam 3, a pretension nut 4 and a second pull rod 5.
The O-shaped plate frame 1 is formed by the combination of O-shaped plates, the O-shaped plate frame 1 comprises a front O-shaped plate frame 11 and a rear O-shaped plate frame 12, a pre-tightening beam 3 comprises a first pre-tightening beam 31 and a second pre-tightening beam 32, the first pre-tightening beam 31 is located at the upper end of the O-shaped plate frame 1, the two sides of the upper end of the O-shaped plate frame 1 are symmetrically distributed, the first end of the first pre-tightening beam 31 is connected with the upper end of the front O-shaped plate frame 11, the second end of the first pre-tightening beam 31 is connected with the upper end of the rear O-shaped plate frame 12, the second pre-tightening beam 32 is located at the lower end of the O-shaped plate frame 1, the two sides of the lower end of the O-shaped plate frame 1 are symmetrically distributed, the first end of the second pre-.
The first end of the first pull rod 2 is connected with the first pre-tightening beam 31 through the pre-tightening nut 4, the second end of the first pull rod 2 is connected with the second pre-tightening beam 32 through the pre-tightening nut 4, the first end of the second pull rod 5 is fixedly connected with the front O-shaped plate frame 11 through the pre-tightening nut 4, the second end of the second pull rod 5 is fixedly connected with the rear O-shaped plate frame 12 through the pre-tightening nut 4, the first pull rod 2 is distributed in a bilateral symmetry mode relative to the longitudinal direction of the O-shaped plate frame 1, the second pull rod 5 is uniformly distributed along the transverse direction of the O-shaped plate frame 1, the pre-tightening nut 4 is used for achieving assembling and longitudinal pre-tightening of a hydraulic machine frame structure, and deformation of the O-shaped plate frame.
The pre-tightening beams 3 are distributed in the hydraulic machine frame structure in a vertical and bilateral symmetry manner, further, in order to ensure the stability and reliability of the actual operation of the hydraulic machine frame structure, one pre-tightening beam 3 or a group of pre-tightening beams 3 are arranged at the installation position of the pre-tightening beam 3 according to the working condition of the hydraulic machine frame structure, and the pre-tightening beam 3 and the first pull rod 2 are in the same plane.
Preferably, the number of the O-shaped plate frames 1 can be two or more; each group of O-shaped plate frames 1 can be formed by a single O-shaped plate or a plurality of O-shaped plates.
In a preferred embodiment of the present invention, the length of the pre-tightening beam 3 is greater than the distance between the front O-shaped plate frame 11 and the rear O-shaped plate frame 12, the middle portion of the pre-tightening beam 3 is located between the front O-shaped plate frame 11 and the rear O-shaped plate frame 12, and two ends of the pre-tightening beam 3 respectively extend out of the front end of the front O-shaped plate frame 11 and the rear end of the rear O-shaped plate frame 12.
As shown in fig. 2, first pull rods are arranged between the front O-shaped plate frame 11 and the rear O-shaped plate frame 12, and at the front end of the front O-shaped plate frame 11 and the rear end of the rear O-shaped plate frame 12.
Specifically, the pre-tightening beam 3 and the first pull rod 2 are arranged on the inner side of the center line of the longitudinal side frame of the O-shaped plate frame 1, and the resultant force of the applied pre-tightening forces is also located on the inner side of the center line of the longitudinal side frame of the O-shaped plate frame 1.
The invention mainly applies longitudinal pretightening force to the O-shaped plate frame 1 of the existing plate-frame type frame so as to improve the strength and rigidity of the frame and reduce the weight of the frame. According to the frame structure of the plate-and-frame hydraulic machine, a pre-tightening coefficient z is taken to be 0.4-0.6, and pre-compression is generated on the longitudinal side frame of the O-shaped plate frame 1 under the action of pre-tightening force. After bearing, the O-shaped plate frame 1 and the first pull rod 2 bear the action of working load at the same time, and at the moment, the stretching amount of the longitudinal side frame is smaller than that when the pre-tightening load is not applied, so that the longitudinal deformation of the O-shaped plate frame can be effectively reduced by applying longitudinal pre-tightening force.
The resultant force of the applied pretightening force is positioned at the inner side of the central line of the longitudinal side frame, and when the longitudinal side frame is not loaded, the longitudinal side frame can generate outward bending deformation. After bearing, the original outward bending deformation is gradually changed into the inward bending deformation under the action of the working load, and at the moment, the position with the maximum bending deformation of the longitudinal side frame is closer to the central line of the initial longitudinal side frame than the position without applying the pre-tightening load, so the bending deformation of the O-shaped plate frame 1 during bearing can be reduced by applying the pre-tightening force.
Usually, the O-shaped plate frame 1 of the frame main body of the plate-frame type hydraulic machine is formed by splicing rolled steel plates and is limited by materials, if the strength and the rigidity of the frame are required to be ensured, the number of the O-shaped plates or the size of the plate frame needs to be increased, and the frame is huge and heavy. By adopting a pre-tightening plate-frame type frame structure, the first pull rod 2 and the longitudinal side frame can bear tensile stress at the same time, so that the tensile load of the side frame is reduced. The first pull rod 2 is a forged piece, the internal quality is good, and the tensile load bearing capacity is strong after heat treatment. The weight of the first tie rod 2 required is less than the weight of the rolled steel sheet under the same tensile load.
The frame structure of the plate-and-frame type hydraulic machine with pretension and the method for optimizing the pretension parameters are further described by combining the following embodiments:
s1, determining the size of the pretightening force in the frame structure of the plate-and-frame hydraulic machine:
s11, analyzing the stress of the O-shaped plate frame 1 when bearing a nominal load according to the specific structure shown in the figures 1 and 2, and taking 1/2 of the plate frame type hydraulic machine frame for analysis according to the symmetry of the structure and the load, namely analyzing the stress of the front O-shaped plate frame 11, wherein the stress and deformation of each part after being split are simplified as shown in figure 7; for a plate-frame type hydraulic machine frame, a working hydraulic cylinder is hoisted at the upper part in an O-shaped plate frame 1, and the cylinder bottom of the hydraulic cylinder and a workbench are respectively contacted with the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 and bear load. The length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 is set to be L, and the contact span ratio alpha is introduced, so that the contact length of a workbench at the bottom of the hydraulic cylinder and the upper frame and the lower frame is set to be alpha L. In addition, when the O-shaped plate frame 1 bears the nominal load, the unit length bearing pressure of the upper frame and the lower frame is q, that is, the bearing size of one group of the O-shaped plate frame 1 is q α L.
Because the compression rebound quantity of the upper and lower horizontal frames of the O-shaped plate frame 1 is very small and can be ignored during bearing, the compression rebound quantity delta L of the longitudinal side frames of the O-shaped plate frame 1 can be considered in the loading process1Re-extension amount DeltaL of first pull rod 22Equal, i.e. Δ L1＝ΔL2The specific expression is as follows:
Figure BDA0002775094860000131
Figure BDA0002775094860000132
in the formula, F0Is the resultant of the pretension force of the one-sided first pull rod 2, FPreparation of＝4×F0；F1The side frame bears axial pressure when bearing; f2The first pull rod 2 on one side is under the tension force when bearing; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the single-sided first pull rods 2; h1The net height of the side frame of the O-shaped plate frame 1 is the transverse upper and lower frame interval of the O-shaped plate frame 1; h2The effective length of the first pull rod 2 is the distance between the upper and lower pre-tightening nuts of the first pull rod 2; e is the modulus of elasticity.
S12, calculating the tension-compression stiffness ratio m of the first pull rod 2 and the longitudinal side frame of the O-shaped plate frame 1;
let m be the ratio of the tension-compression stiffness of the first pull rod 2 on the single side of the O-shaped plate frame 1 and the longitudinal side frame, and the calculation expression is as follows:
Figure BDA0002775094860000141
in the formula, m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the single-sided first pull rods 2; h1The net height of the side frame of the O-shaped plate frame 1 is the transverse distance between the upper frame and the lower frame of the O-shaped plate frame 1; h2The effective length of the first pull rod 2 is the distance between the upper and lower pretension nuts 4 in the first pull rod 2.
S13, combining the tension-compression stiffness ratio m obtained in the step S12 with the deformation balance condition of the plate frame type hydraulic machine frame structure under an ideal state to obtain the pretightening force of the first pull rod 2 and the tension applied to the first pull rod 2 after bearing;
s131, from steps S11 and S12, it is possible to:
F2-F1＝(1+m)(F0-F1)。
in the formula, m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; f0Is the resultant of the pretension force of the one-sided first pull rod 2, FPreparation of＝4×F0；F1The side frame bears axial pressure when bearing; f2Is the tension force to which the first pull rod 2 on one side is subjected when bearing load.
S132, according to balance conditions, under the bearing state of the frame structure of the plate-frame type hydraulic machine:
Figure BDA0002775094860000142
under the ideal state, when the frame structure of the plate-frame type hydraulic machine bears the load, the compression resilience amount of the longitudinal side frame is equal to the precompression amount, and the side frame does not bear the stress, namely F1When the ratio is 0, the following:
Figure BDA0002775094860000143
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame 1; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; and q is the unit length bearing pressure of the upper frame and the lower frame.
S133, substituting the above formula into step S131, an expression of the magnitude of the resultant pre-tightening force of the one-side first pull rod 2 can be obtained:
Figure BDA0002775094860000144
in the formula, F0Is the resultant of the pretension force of the one-sided first pull rod 2, FPreparation of＝4×F0(ii) a m is the ratio of the tension-compression stiffness of the single-side first pull rod 2 to the longitudinal side frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames in the O-shaped plate frame 1; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; and q is the unit length bearing pressure of the upper frame and the lower frame.
In the above expression A1、A2、H1、H2E depends on the specific structure of the frame of the plate-and-frame hydraulic press andgiven the conditions. As the expression of the total force of the pretightening force of the unilateral first pull rod 2 can be known, the pretightening force to be exerted has a definite mathematical relationship with the rigidity and the nominal load of the O-shaped plate frame 1. The pre-tightening force is closely related to the rigidity of the O-shaped plate frame 1 and the first pull rod 2 and the working load. Under the condition of a certain nominal load, the unilateral pretightening force F0Can be adjusted according to the tension-compression rigidity ratio m of the first pull rod 2 and the longitudinal side frame, the larger the cross-sectional area ratio of the first pull rod 2 and the longitudinal side frame is, the larger the needed exerted unilateral pretightening force F0Smaller and conversely, unilateral preload force F0The larger; under the condition of determining the frame structure parameters of the plate-and-frame hydraulic machine, the unilateral pretightening force F exerted on the O-shaped plate frame 10The ratio is 1 in linear direct proportion to the load carried by the bearing.
S2, determining the specific application position of the pretightening force in the frame structure of the plate-and-frame hydraulic machine, and obtaining the unilateral pretightening force F0The tension F borne by the first pull rod 2 on one side during working2And solving by combining specific frame structure parameters of the plate-and-frame hydraulic machine, so that the specific application position of the pre-tightening force can be obtained:
s21, under the bearing state of the frame of the plate-and-frame hydraulic press, the transverse upper frame and the transverse lower frame bear the working load q alpha L and the pulling force F of the first pull rod 2 respectively2The frame deformation of the O-shaped plate frame 1 is calculated by adopting an superposition method under the combined action of the two components; introducing pretightening force position ratio beta and unilateral pretightening force F0The distance between the application position and the central line of the longitudinal side frame is beta L;
because the O-shaped frame 1 is a whole, the bending rigidity of each position tends to generate interactive influence on the deformation of the O-shaped plate frame 1, and therefore, when the deformation of the O-shaped plate frame 1 is calculated, an interactive deformation coefficient lambda is introduced1、λ2Respectively calculating the bending moments of corners of the transverse frame and the lower frame:
Figure BDA0002775094860000151
Figure BDA0002775094860000152
in the formula, λ1、λ2The cross deformation coefficients of the transverse frame and the lower frame are obtained; a ═ γ2+2γ(K1+K2)，B＝3K1K2(ii) a Gamma is the ratio of the height H of the longitudinal side frame of the O-shaped plate frame 1 to the length L of the transverse upper and lower frames of the O-shaped plate frame 1, and gamma is H/L; k1Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame1The ratio of (A) to (B); k2Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame2The ratio of.
S211, when the sizes of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 are consistent, namely K1＝K2＝K，λ1＝λ2Lambda, simultaneously, when the plate and frame hydraulic press frame only bore operating load, the expression of the corner moment of bending of O type sheet frame 1 is:
Figure BDA0002775094860000161
in the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame 1; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; and lambda is an interactive deformation coefficient.
S212, when the frame of the plate-and-frame hydraulic press bears the load, the first pull rod 2 bears the tension F2The bending moment to the corner of the O-shaped plate frame 1 is as follows:
Figure BDA0002775094860000162
in the formula, M2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; l is O-shaped plate frame 1 horizontalThe length of the upper frame and the lower frame, namely the distance between the center lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; and lambda is an interactive deformation coefficient.
S213, combining the steps S211 and S212, under the condition of a given pretightening force, after the O-shaped plate frame 1 bears, the bending moment of the corner is as follows:
M0＝M1+M2
the horizontal deformation of the middle point of the longitudinal side frame is as follows:
Figure BDA0002775094860000163
in the formula, W is the horizontal deformation of the midpoint of the longitudinal side frame of the O-shaped plate frame 1; m1Bending moment of the working load to the corner of the O-shaped plate frame 1; m2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame 1; m0Under the given pretightening force, the O-shaped plate frame 1 bears the bending moment of the rear corner; i is the section moment of inertia of the longitudinal side frame of the O-shaped plate frame 1.
S22, calculating the specific position of the pre-tightening force exerted on the O-shaped plate frame 1 under the conditions that the working load borne by the O-shaped plate frame 1, the pre-tightening force and the dimensional parameters are determined and the dimensional parameters are fixed according to the principle that the deformation of the O-shaped plate frame 1 after bearing is minimum,
since the horizontal deformation W of the center point of the longitudinal side frame of the O-shaped plate frame 1 is 0 in the ideal state, the expression in step S21 is given as follows:
Figure BDA0002775094860000164
i.e. M1＝-M2，(3-3α+α2)＝48β2(1-β)2
From this, the mathematical relationship between the pretightening force position ratio β and the contact span ratio α is expressed as:
Figure BDA0002775094860000171
in the formula, W is the horizontal deformation of the midpoint of the longitudinal side frame; m1Bending moment of the working load to the corner of the O-shaped plate frame 1; m2Is the tension F of the first pull rod 22Bending moment of the corner of the O-shaped plate frame 1; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; h is the height of the longitudinal side frame of the O-shaped plate frame 1, namely the distance between the center lines of the transverse upper frame and the transverse lower frame. .
From the above expression, in the case of determining the magnitude of the preload, the preload position ratio β is closely related to the contact span ratio α. When the contact span ratio alpha is gradually increased, the pretightening force position ratio beta is gradually reduced; conversely, the preload position ratio β gradually increases.
When the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 is fixed, the contact length of the cylinder bottom of a hydraulic cylinder in the frame of the plate frame type hydraulic machine, the contact length of a workbench and the transverse upper frame and the contact length of the workbench in the transverse upper frame and the transverse lower frame are longer, and the first pull rod 2 is closer to the central line of the longitudinal side frame; conversely, the shorter the contact length with the transverse upper and lower frames, the farther the first pull rod 2 should be from the center line of the longitudinal side frame.
When the sizes of the hydraulic cylinder and the workbench are fixed, the larger the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame 1 is, the larger the length of the transverse upper frame and the transverse lower frame is, the larger the first pull rod 2 is, and the distance from the central line of the longitudinal side frame is correspondingly kept away; conversely, the smaller the length of the transverse upper and lower frames is, the closer the first pull rod 2 should be to the center line of the longitudinal side frame. The expression can be used for calculating the specific position of the applied pretightening force under different contact conditions, and the minimum deformation of the loaded O-shaped plate frame is ensured.
Carrying out simulation analysis on the frame structure of the plate-frame type hydraulic machine with the pre-tightening function, wherein the pre-tightening coefficient z is 0.4, FPreparation of＝0.4×FLoad(s)And each group of O-shaped plate frames 1 comprises 9O-shaped plates, and on the basis of the existing plate frame type frame structure, the rigidity of the plate frame type frame is improved by increasing the width size of the longitudinal side frame of each O-shaped plate frame 1 and increasing the number of the O-shaped plates in each group of O-shaped plate frames 1. The setting conditions were as follows:
1. the initial width of the longitudinal side frame of the O-shaped plate frame 1 is 3500mm, the number of the O-shaped plates is kept unchanged, and the widths are increased to 4500mm, 5500mm and 6500mm in sequence;
2. the initial number of the O-shaped plates in each group of O-shaped plate frames 1 is 9, the width of the longitudinal side frame is kept unchanged, and the number of the O-shaped plates is sequentially increased to 10, 11 and 12.
According to the simulation result, three reference points are selected on the O-shaped plate in the O-shaped plate frame 1, and the three reference points are respectively positioned at the transition round corner of the frame and the middle position of the side frame. The selection of the reference point on the O-shaped plate frame 1 is shown in fig. 8. By comparing the relative positional changes of the three reference points, the deformation amount data of the O-shaped plate frame 1 is obtained, in which the maximum displacement of the point B in the longitudinal direction with respect to the point C represents the amount of elongation deformation of the longitudinal side frame, and the maximum displacement of the point a in the transverse direction with respect to the point C represents the amount of bending deformation of the longitudinal side frame. The deformation of the O-shaped plate frame and the weight of the frame are shown in Table 1.
TABLE 1O-shaped plate frame deflection and Rack weight data
Figure BDA0002775094860000181
On the basis of the same O-shaped plate frame 1, compared with the pre-tightening plate frame type frame and the existing plate frame type frame, the pre-tightening members such as the pull rod are additionally arranged, so that the weight of the pre-tightening plate frame type frame is increased by 17095KN, and the amplification is 14.1%; the elongation deformation of the longitudinal side frame is reduced by 5.51mm, and the reduction amplitude is 36.0%; the bending deformation of the longitudinal side frame is reduced by 1.21mm, and the amplitude reduction is 16.6%.
By adopting the existing plate-and-frame type frame, when the width of the longitudinal side frame of the O-shaped plate frame 1 is 4500mm, the weight of the frame is 145318KN, and by adopting a pre-tightening plate-and-frame type structure, the weight of the frame is reduced by 6774KN, and the amplitude reduction is 4.7%; the elongation deformation of the longitudinal side frame is reduced by 3.69mm, and the reduction amplitude is 27.4%; the bending deformation of the longitudinal side frame is reduced by 0.38mm, and the reduction is 5.9%.
By adopting the existing plate-and-frame type frame, when the width of the longitudinal side frame of the O-shaped plate frame 1 is 5500mm, the weight of the frame is 169188KN, and by adopting a pre-tightening plate-and-frame type structure, the weight of the frame is reduced by 30644KN, and the amplitude reduction is 18.1%; the elongation deformation of the longitudinal side frame is reduced by 2.59mm, and the reduction amplitude is 20.9%; the bending deformation of the longitudinal side frame is increased by 0.08mm, and the amplification is 1.3%.
The existing plate-frame type frame is adopted, when the width of the longitudinal side frame of the O-shaped plate frame 1 is 6500mm, the weight of the frame is 193057KN, and the pre-tightening plate-frame type structure is adopted, so that the weight of the frame is reduced by 54513KN, and the amplitude reduction is 28.2%; the elongation deformation of the longitudinal side frame is reduced by 1.85mm, and the reduction amplitude is 15.9%; the bending deformation of the longitudinal side frame is increased by 0.55mm, and the amplification is 9.9%.
The existing plate-and-frame type frame is adopted, when the number of O-shaped plates in the O-shaped plate-and-frame 1 group is 10, the weight of the frame is 134900KN, a pre-tightening plate-and-frame type structure is adopted, the weight of the frame is increased by 3644KN, and the amplification is 2.7%; the elongation deformation of the longitudinal side frame is reduced by 3.95mm, and the reduction amplitude is 28.8%; the bending deformation of the longitudinal side frame is reduced by 0.58mm, and the amplitude reduction is 8.7%.
The existing plate-and-frame type frame is adopted, when the number of the O-shaped plates in the O-shaped plate-and-frame 1 group is 11, the weight of the frame is 148351KN, a pre-tightening plate-and-frame type structure is adopted, the weight of the frame is reduced by 9807KN, and the amplitude reduction is 6.6%; the elongation deformation of the longitudinal side frame is reduced by 2.76mm, and the reduction amplitude is 22.0 percent; the bending deformation of the longitudinal side frame is increased by 0.02mm, and the amplification is 0.3%.
The existing plate-frame type frame is adopted, when the number of the O-shaped plates in the O-shaped plate frame 1 group is 12, the weight of the frame is 161801KN, a pre-tightening plate-frame type structure is adopted, the weight of the frame is reduced by 23257KN, and the amplitude reduction is 14.4%; the elongation deformation of the longitudinal side frame is reduced by 1.64mm, and the reduction amplitude is 14.4%; the bending deformation of the longitudinal side frame is increased by 0.65mm, and the amplification is 11.9%.
According to the comparative analysis, the pre-tightening plate-frame type frame structure is adopted, so that the longitudinal rigidity of the frame is improved and the deformation of the O-shaped plate frame is reduced on the premise of effectively reducing the weight of the frame.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims (8)

1. A pre-tightening force parameter optimization method for a frame of a plate-and-frame hydraulic machine is characterized by comprising the following steps:
s1, determining the size of the pretightening force in the frame structure of the plate-and-frame hydraulic machine:
s11, analyzing the stress of the O-shaped plate frame according to the actual engineering condition, making a stress and deformation diagram after the O-shaped plate frame is split, and making the compression rebound quantity delta L of the longitudinal side frame of the O-shaped plate frame in the loading process1Re-extension amount DeltaL of first pull rod2Equal, i.e. Δ L1＝ΔL2The specific expression is as follows:
Figure FDA0002775094850000011
Figure FDA0002775094850000012
in the formula, F0The resultant force of the pretightening force of the first pull rod on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod on one side is under the tension when bearing; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the one-sided first pull rods; h1The net height of the side frame of the O-shaped plate frame is the distance between the transverse upper frame and the transverse lower frame of the O-shaped plate frame; h2The effective length of the first pull rod is the distance between the upper and lower pre-tightening nuts of the first pull rod; e is the modulus of elasticity;
s12, calculating the tension-compression rigidity ratio m of the first pull rod and the longitudinal side frame of the O-shaped plate frame, wherein m is the tension-compression rigidity ratio of the first pull rod on the single side of the O-shaped plate frame and the longitudinal side frame, and the calculation expression is as follows:
Figure FDA0002775094850000013
in the formula, m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; a. the1Is the cross-sectional area of the longitudinal side frame on one side; a. the2Is the sum of the cross-sectional areas of the one-sided first pull rods; h1The net height of the side frame of the O-shaped plate frame is the distance between the transverse upper frame and the transverse lower frame of the O-shaped plate frame; h2The effective length of the first pull rod is the distance between the upper and lower pre-tightening nuts of the first pull rod;
s13, combining the tension-compression stiffness ratio m obtained in the step S12 with the deformation balance condition of the plate frame type hydraulic machine frame structure in an ideal state to obtain the pretightening force of the first pull rod and the tension applied to the first pull rod after bearing;
in step S13, the specific steps of obtaining the resultant force of the first tie bar pretightening force are as follows:
s131, resulting from steps S11 and S12:
F2-F1＝(1+m)(F0-F1)
in the formula, m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; f0The resultant force of the pretightening force of the first pull rod on one side; f1The side frame bears axial pressure when bearing; f2The first pull rod on one side is under the tension when bearing;
s132, according to the balance condition, under the bearing state of the frame structure of the plate-frame type hydraulic machine, the following expression is shown:
Figure FDA0002775094850000021
under the ideal state, when the frame structure of the plate-frame type hydraulic machine bears the load, the compression resilience amount of the longitudinal side frame is equal to the precompression amount, and the side frame does not bear the stress, namely F1When the ratio is 0, the following:
Figure FDA0002775094850000022
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame;
s133, substituting the formula into the step S131 to obtain an expression of the magnitude of the resultant force of the first pull rod on one side, wherein the expression is as follows:
Figure FDA0002775094850000023
in the formula, F0The resultant force of the pretightening force of the first pull rod on one side; m is the ratio of the tension-compression stiffness of the first pull rod on one side to the longitudinal side frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the upper and lower frames of the O-shaped plate frame; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame;
s2, determining the specific application position of the pretightening force in the frame structure of the plate-frame type hydraulic machine:
s21, respectively calculating the deformation influence of the actual working load and the tension on the O-shaped plate frame caused by the first pull rod after bearing in the step S13, and introducing an interactive deformation coefficient lambda1、λ2Respectively calculating the corner bending moments of a transverse frame and a lower frame in the O-shaped plate frame, and calculating the deformation of a longitudinal side frame of the O-shaped plate frame by adopting an superposition method, wherein the interactive deformation coefficient expression is as follows:
Figure FDA0002775094850000024
Figure FDA0002775094850000025
in the formula, λ1、λ2The cross deformation coefficients of the transverse frame and the lower frame are obtained; a ═ γ2+2γ(K1+K2)，B＝3K1K2(ii) a Gamma is the height H of the vertical side frame of the O-shaped plate frame and the horizontal upper and lower frames of the O-shaped plate frameThe ratio of the length L, γ ═ H/L; k1Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame1The ratio of (A) to (B); k2Bending rigidity EI of longitudinal side frame and bending rigidity (EI) of transverse frame2The ratio of (A) to (B);
in step S21, the specific determination step of the deformation size of the longitudinal side frame of the O-shaped plate frame is as follows:
s211, when the sizes of the upper frame and the lower frame of the O-shaped plate frame are consistent, namely K1＝K2＝K，λ1＝λ2Lambda, simultaneously, when the plate and frame hydraulic press frame only bore operating load, the expression of the corner moment of bending of O type sheet frame is:
Figure FDA0002775094850000031
in the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; lambda is an interactive deformation coefficient;
s212, when the frame of the plate-and-frame hydraulic press bears the load, the first pull rod bears the tension F2The bending moment to the corner of the O-shaped plate frame is as follows:
Figure FDA0002775094850000032
in the formula, M2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the pretightening force position ratio; l is the length of the transverse upper frame and the transverse lower frame of the O-shaped plate frame, namely the distance between the central lines of the longitudinal side frames; q is the unit length bearing pressure of the upper frame and the lower frame; lambda is an interactive deformation coefficient;
s213, combining the steps S211 and S212, under the condition of a given pretightening force, after the O-shaped plate frame bears, the bending moment of the corner is as follows:
M0＝M1+M2
the horizontal deformation of the middle point of the longitudinal side frame is as follows:
Figure FDA0002775094850000033
in the formula, W is the horizontal deformation of the midpoint of the longitudinal side frame of the O-shaped plate frame; m1Bending moment of the working load to the corner of the O-shaped plate frame; m2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; m0Under the given pretightening force, the O-shaped plate frame bears the bending moment of the rear corner; i is the section moment of inertia of the longitudinal side frame of the O-shaped plate frame;
s22, calculating the specific position of the pre-tightening force exerted on the O-shaped plate frame under the condition that the working load, the pre-tightening force and the structural dimension parameters are fixed according to the principle that the deformation of the loaded O-shaped plate frame is minimum, and obtaining the relation between the pre-tightening force position ratio beta and the contact span ratio alpha:
Figure FDA0002775094850000041
in the formula, alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the pretightening force position ratio.
2. The pretightening force parameter optimization method for the frame of the plate-and-frame hydraulic machine as claimed in claim 1, wherein in step S22, under an ideal condition, the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame is 0, and the specific expression of the horizontal deformation W obtained by the calculation process in step S21 is as follows:
Figure FDA0002775094850000042
according to the specific expression of the horizontal deformation W of the midpoint of the longitudinal side frame of the O-shaped plate frame, M can be known1＝-M2，(3-3α+α2)＝48β2(1-β)2；
In the formula, M1Bending moment of the working load to the corner of the O-shaped plate frame; m2Is the tension F of the first pull rod2Bending moment of the corner of the O-shaped plate frame; alpha is the contact span ratio of the hydraulic cylinder and the workbench to the transverse upper and lower frames; beta is the ratio of the pretightening force position, namely the ratio of the distance between the pretightening force applying position and the center line of the longitudinal side frame to the length of the transverse upper and lower frames; h is the height of the vertical side frame of the O-shaped plate frame, namely the distance between the center lines of the horizontal upper frame and the horizontal lower frame.
3. The plate-frame hydraulic machine frame device for the pre-tightening force parameter optimization method of the plate-frame hydraulic machine frame according to claim 1 is characterized by comprising an O-shaped plate frame, a first pull rod, a pre-tightening beam, a pre-tightening nut and a second pull rod; the O-shaped plate frame comprises a front O-shaped plate frame and a rear O-shaped plate frame, the pre-tightening beams comprise a first pre-tightening beam and a second pre-tightening beam, the first pre-tightening beam is positioned at the upper end of the O-shaped plate frame and symmetrically distributed on two sides of the upper end of the O-shaped plate frame, the first end of the first pre-tightening beam is connected with the upper end of the front O-shaped plate frame, the second end of the first pre-tightening beam is connected with the upper end of the rear O-shaped plate frame, the second pre-tightening beam is positioned at the lower end of the O-shaped plate frame and symmetrically distributed on two sides of the lower end of the O-shaped plate frame, the first end of the second pre-tightening beam is connected with the lower end of the front O-shaped plate frame, and the second end of the second pre-tightening; the first end of the first pull rod is connected with the first pre-tightening beam through a pre-tightening nut, the second end of the first pull rod is connected with the second pre-tightening beam through a pre-tightening nut, the first pull rod is distributed in a bilateral symmetry mode in the longitudinal direction of the O-shaped plate frame, the first end of the second pull rod is fixedly connected with the front O-shaped plate frame through a pre-tightening nut, the second end of the second pull rod is fixedly connected with the rear O-shaped plate frame through a pre-tightening nut, the second pull rod is uniformly distributed in the transverse direction of the O-shaped plate frame, the pre-tightening nut achieves assembly and longitudinal pre-tightening of a frame structure of the hydraulic machine, and deformation of the O-shaped plate frame in the stress process is reduced.
4. The frame device of a plate and frame hydraulic machine according to claim 3, wherein the pre-tightening beam and the first pull rod are arranged on the inner side of the center line of the longitudinal side frame of the O-shaped plate frame, and the sum of the pre-tightening forces exerted by the plurality of pull rods is arranged on the inner side of the center line of the longitudinal side frame of the O-shaped plate frame.
5. The frame device of a plate and frame hydraulic machine according to claim 3, wherein the number of the O-shaped plate frames is two or more.
6. The frame apparatus of a plate and frame hydraulic machine of claim 3, wherein each group of O-shaped plates is formed by a single O-shaped plate or by a combination of a plurality of O-shaped plates.
7. The plate and frame type hydraulic machine frame device according to claim 3, wherein the pre-tightening beams are distributed in the hydraulic machine frame structure in a vertically or horizontally symmetrical manner, one pre-tightening beam or a group of pre-tightening beams is selectively installed at a pre-installation position of the pre-tightening beam according to the working condition of the hydraulic machine frame structure, and the pre-tightening beam and the first pull rod are located in the same plane.
8. The frame device of a plate and frame hydraulic machine according to claim 3, wherein the length of the pre-tightening beam is greater than the distance between the front O-shaped plate frame and the rear O-shaped plate frame, the middle part of the pre-tightening beam is located between the front O-shaped plate frame and the rear O-shaped plate frame, and two ends of the pre-tightening beam respectively extend out of the front end of the front O-shaped plate frame and the rear end of the rear O-shaped plate frame.
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