A method for optimizing design of a cross beam in a ROPS framework and an engineering machine cab

Abstract

The application discloses a kind of ROPS skeleton middle beam optimization design method and engineering machinery cab, and the design method includes: by analyzing the influence of the height size of middle beam in portal hyperstatic structure mechanics model on the distribution relationship of two bending moments on stand column, the height size of middle beam is solved when the maximum bending moment on stand column is minimum, and the optimal height size relationship of middle beam is obtained;By analyzing the design target that middle beam and stand column enter plastic deformation zone at the same time, the sectional parameter design relationship of middle beam section is obtained, and the relationship is used to guide the selection of ROPS skeleton structure and section, to improve the design quality of ROPS skeleton.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering machinery cabs and relates to a crossbeam optimization design method for a ROPS frame and an engineering machinery cab. Background Art

[0002] Construction machinery operates in harsh environments, and the Rollover Protection Structure (ROPS) frame has become standard equipment in cab configurations. Testing requires that the ROPS frame meet requirements for lateral, vertical, and longitudinal loads, as well as lateral load energy. Under lateral loads, the cab undergoes an elastic-plastic deformation state, and plastic hinges form in the frame at locations with maximum bending moments or structural weaknesses. These plastic hinges allow for significant lateral deformation of the frame, facilitating the absorption of lateral impact load energy.

[0003] The center crossbeam can increase the number of plastic hinges and significantly improve the load-bearing capacity of the ROPS frame. However, the height and cross-sectional dimensions of the center crossbeams of various OEMs vary. The traditional design method is that designers build the ROPS frame based on empirical data and then optimize the structure based on simulation analysis. This method suffers from the problems of insufficient designer experience and long design cycles. A convenient optimization design method is urgently needed.

[0004] Objective: To overcome the deficiencies in the prior art, the present invention provides a method for optimizing the design of a crossbeam in a ROPS framework and an engineering machinery cab.

[0005] The present invention provides a design method for the height arrangement position of a crossbeam in a ROPS frame, and also provides a design method for the optimal ratio relationship of the crossbeam and column cross-sectional inertia moments in the ROPS frame, thereby realizing a lightweight design of the ROPS frame.

[0006] The present invention provides an optimized ROPS skeleton structure by analyzing the loading characteristics of the ROPS test.

[0007] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0008] In a first aspect, a central axis symmetrical ROPS frame is provided, comprising uprights, cross beams, longitudinal beams, and a center cross beam;

[0009] The vertical columns include A columns, B columns, and D columns; the cross beams include top cross beams and bottom cross beams; and the longitudinal beams include top longitudinal beams and bottom longitudinal beams.

[0010] The two A-pillars are connected by a first top crossbeam and a first bottom crossbeam to form a closed rectangular A-ring;

[0011] The two B-pillars are connected by the second top cross member and the second bottom cross member to form a closed rectangular B-ring;

[0012] The two D-pillars are connected by a third top crossbeam and a third bottom crossbeam to form a closed rectangular D-ring; the two ends of the middle crossbeam are respectively connected to the inner sides of the middle parts of the two D-pillars, and the third top crossbeam, the middle crossbeam and the third bottom crossbeam are arranged in parallel;

[0013] The four corners corresponding to the A ring and the B ring are connected by the first top longitudinal beam and the first bottom longitudinal beam, and the four corners corresponding to the B ring and the D ring are connected by the second top longitudinal beam and the second bottom longitudinal beam, forming a closed space frame structure.

[0014] In some embodiments, the ratio of the center cross beam height dimension Ld to the D-pillar length dimension L is n1, and the value of n1 is 0.45-0.55.

[0015] In some embodiments, the ratio of the cross-sectional inertia moments of the center beam and the D-pillar is n2, and the value of n2 is 1.15 to 1.45.

[0016] In a second aspect, a method for optimizing the crossbeam design of the axisymmetric ROPS framework is provided, comprising:

[0017] S1 Create a mechanical model: According to the ROPS skeleton structure, extract the length dimension W of the middle beam, the length dimension L of the column and the height dimension L of the middle beam d , forming a portal-type statically indeterminate structural mechanics model;

[0018] S2 Selected design parameters: The height dimension L of the middle crossbeam is obtained based on the ROPS test data analysis d It can affect the lateral load capacity of ROPS and select the height dimension L of the middle beam. d As the design parameter of the ROPS skeleton structure; the section inertia moment I of the profile is the key factor that determines the bending moment distribution in the mechanical model, so the section inertia moment I of the profile is selected as the design parameter of the profile;

[0019] S3 Structural Mechanics Analysis: Use structural mechanics analysis software to analyze the bending moment stress value of the portal type statically indeterminate structural mechanics model and obtain the maximum bending moment Max (M 立柱底 , M 立柱中 ) The minimum height of the middle beam L d , thus obtaining the height dimension L of the middle beam d The ratio n1 to the column length L;

[0020] The structural mechanics analysis software is used to analyze the bending moment stress value of the portal frame type statically indeterminate structural mechanics model and obtain the height dimension L of the beam. d When the optimal height dimension is adopted and the maximum bending moment stress of the cross beam and column in the ROPS frame is equal, the ratio of the cross beam and column section inertia moment n2 is in the range of 1.15 to 1.45;

[0021] S4 creates a relationship: According to the height dimension L of the middle beam d The ratio n1 of the length dimension L of the column is used to obtain the optimal height dimension relationship of the middle beam;

[0022] According to the ratio of the cross-sectional inertia moments n2 of the middle cross-section beam and the columns, the design relationship of the cross-sectional parameters of the middle cross-section beam is obtained;

[0023] The height layout position of the middle cross beam of the ROPS frame is determined according to the middle cross beam optimal height dimension relationship, and the profiles of the middle cross beam and the corresponding columns are selected according to the middle cross beam profile section parameter design relationship.

[0024] In some embodiments, the length dimension W of the middle cross beam is 1.45m to 1.6m; the length dimension L of the column is 1.65m to 1.9m.

[0025] In some embodiments, the optimal height dimension relationship of the middle crossbeam is: L d =n1·L. Furthermore, the value range of n1 is 0.45 to 0.55.

[0026] In some embodiments, the middle crossbeam optimization design relationship is: 中_横梁 =n2·I 立柱 Furthermore, the ratio n2 of the cross-sectional inertia moments of the middle cross beam and the vertical columns is 1.15 to 1.45.

[0027] In a third aspect, the present invention further provides an engineering machinery cab, comprising the aforementioned axisymmetric ROPS frame.

[0028] Beneficial Effects: The present invention provides a method for optimizing the design of the center crossbeam of a ROPS frame and an engineering machinery cab. By analyzing the structural mechanics model, the optimal height of the center crossbeam and the optimal ratio of the cross-sectional inertia moments of the center crossbeam and columns are determined. This method can significantly shorten the design time of the ROPS frame and improve the design quality. It has the following advantages:

[0029] (1) The present invention provides a design method for the height arrangement position of the cross beam in the ROPS frame; and provides a design method for the optimal ratio relationship of the cross beam and column cross-sectional inertia moments in the ROPS frame;

[0030] (2) The present invention provides a closed "ring-shaped" ROPS skeleton structure that is conducive to force transmission;

[0031] (3) The design method of the present invention can be embedded in an intelligent design software database. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Flowchart of the crossbeam optimization design method for the ROPS frame in the embodiment;

[0033] Figure 2 The crossbeam reinforcement structure of the ROPS frame in the embodiment;

[0034] Figure 3 Schematic diagram of the ROPS skeleton portal type hyperstatic structural mechanical model in the embodiment.

[0035] In the figure: column 1, top crossbeam 2, middle crossbeam 3 and bottom crossbeam 4, corner brace 5, and limit device 6. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0038] In the description of the present disclosure, it should be understood that the use of words such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0039] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0040] Definition of professional terms:

[0041] ROPS - Rollover Protective Structure, a series of structural components that reduces the possibility of crushing and injuring a driver wearing a seatbelt when the machine rolls over.

[0042] ROPS frame - a space frame structure constructed to meet ROPS design requirements;

[0043] Column - a component or member that serves as a vertical support;

[0044] Crossbeam - a beam structural member arranged transversely;

[0045] Top beam - the crossbeam member at the top of the frame;

[0046] Section moment of inertia I is the integral of the product of the area of ​​each element of the cross section and the square of the distance from each element to a specified axis on the cross section. It is a geometric parameter that measures the bending resistance of a component section. Unless otherwise specified in this article, the axis of the section moment of inertia passes through the centroid of the cross section.

[0047] Plastic hinge: When a ROPS frame is subjected to bending moment, a certain point appears locally in the component, where the opposite surface yields but does not fail, and the component can rotate around a limited angle. This point can be called a plastic hinge.

[0048] Plastic deformation zone - When lateral loading occurs, multiple plastic hinges appear in the ROPS frame, making it impossible for the ROPS frame to continue to maintain a statically determinate structure. This state is called the plastic deformation zone.

[0049] The design method of the present invention is based on the characteristics of the most demanding side load test in the ROPS test. In order to facilitate the transmission of side loads, Figure 2 The crossbeam reinforcement structure and Figure 3 The portal frame hyperstatic structural mechanical model shown in the figure has two bending moments on the column due to the height of the middle beam: the bending moment M at the bottom of the column 立柱底 and the bending moment M in the middle of the column 立柱中 The influence of the distribution relationship, solve the maximum bending moment Max (M 立柱底 , M 立柱中) is minimized, and the optimal height dimension relationship of the middle beam is obtained; by analyzing the design goal of the middle beam and the column entering the plastic deformation zone at the same time, the ratio relationship of the section inertia moment of the middle beam and the column is obtained, and the relationship is used to guide the selection of ROPS skeleton structure and profile.

[0050] Example 1

[0051] A closed "ring" skeleton structure with a central axis symmetry includes a column 1, a top crossbeam 2, a middle crossbeam 3 and a bottom crossbeam 4; one end of the top crossbeam is connected to the top of one of the two columns, and the other end is connected to the top of the other of the two columns; one end of the bottom crossbeam is connected to the bottom end of one of the two columns, and the other end is connected to the bottom end of the other of the two columns; the two ends of the middle crossbeam are respectively connected to the inner sides of the middle parts of the two columns 1, and the third top crossbeam, the middle crossbeam and the third bottom crossbeam are arranged in parallel; forming a closed "ring" skeleton structure.

[0052] In some embodiments, corner braces 5 are provided at the connection between the upright column 1 and the top cross beam 2 and the middle cross beam 3, and a limiting device 6 is provided at the bottom of the cab ROPS frame.

[0053] In some embodiments, as Figure 2 As shown, a central axis symmetrical cab ROPS frame includes pillars, cross beams, longitudinal beams, and a center cross beam 60;

[0054] The upright columns include A-pillars 10, B-pillars 20, and D-pillars 30; the crossbeams include top crossbeams and bottom crossbeams; and the longitudinal beams include top longitudinal beams and bottom longitudinal beams.

[0055] The two A-pillars 10 are connected by a first top crossbeam 11 and a first bottom crossbeam 12 to form a closed rectangular A-ring;

[0056] The two B-pillars 20 are connected by the second top crossbeam 21 and the second bottom crossbeam 22 to form a closed rectangular B-ring;

[0057] The two D-pillars 30 are connected by a third top crossbeam 31 and a third bottom crossbeam 32 to form a closed rectangular D-ring;

[0058] The two ends of the middle cross beam 60 are respectively connected to the inner sides of the middle parts of the two D-pillars, and the third top cross beam, the middle cross beam and the third bottom cross beam are arranged in parallel;

[0059] The four corners corresponding to the A ring and the B ring are connected by the first top longitudinal beam 41 and the first bottom longitudinal beam 42 , and the four corners corresponding to the B ring and the D ring are connected by the second top longitudinal beam 51 and the second bottom longitudinal beam 52 , forming a closed space frame structure.

[0060] The A ring, B ring and D ring are all rectangular structures, and the entire ROPS frame is an axisymmetric structure.

[0061] In some embodiments, the ratio of the center cross beam height dimension Ld to the D-pillar length dimension L is n1, and the value of n1 is 0.45-0.55; the ratio of the cross beam to the D-pillar's section moment of inertia is n2, and the value of n2 is 1.15-1.45. The ROPS frame is designed using the design method described in Example 2.

[0062] Among them, the longitudinal beams include top longitudinal beams and bottom longitudinal beams. In order to ensure the flatness of the bottom of the entire ROPS frame, the bottom longitudinal beams are basically set in the same plane as the bottom cross beam (for example, horizontally). However, the lengths of the A-pillar, B-pillar, and D-pillar are not necessarily equal, so the top longitudinal beam and the top cross beam are not necessarily located in the same plane.

[0063] Example 2

[0064] like Figure 1 As shown, a method for optimizing the crossbeam design of a central axis symmetrical ROPS frame includes:

[0065] S1 Create a mechanical model: Based on the ROPS skeleton structure, extract the length dimension W of the middle beam (W value is 1.45m~1.6m), the length dimension L of the column (L value is 1.65m~1.9m) and the height dimension L of the middle beam d , forming a portal-type statically indeterminate structural mechanics model;

[0066] S2 Selected design parameters: The height dimension L of the middle crossbeam is obtained based on the ROPS test data analysis d It can affect the lateral load capacity of ROPS and select the height dimension L of the middle beam. d As the design parameter of the ROPS skeleton structure; the section inertia moment I of the profile is the key factor that determines the bending moment distribution in the mechanical model, so the section inertia moment I of the profile is selected as the design parameter of the profile;

[0067] S3 Structural Mechanics Analysis: Use structural mechanics analysis software to analyze the bending moment stress value of the portal type statically indeterminate structural mechanics model and obtain the maximum bending moment Max (M 立柱底 , M 立柱中 ) The minimum height of the middle beam L d , thus obtaining the height dimension L of the middle beam d The ratio n1 to the column length L, the value range of n1 is 0.45~0.55;

[0068] The structural mechanics analysis software is used to analyze the bending moment stress value of the portal frame type statically indeterminate structural mechanics model and obtain the height dimension L of the beam. d When the optimal height dimension is adopted and the maximum bending moment stress of the cross beam and column in the ROPS frame is equal, the ratio of the cross beam and column section inertia moment n2 is in the range of 1.15 to 1.45;

[0069] S4 creates a height dimension relationship: according to the height dimension L of the middle beam d The ratio n1 of the length of the column and the length L gives the optimal height of the middle beam: L d =n1·L

[0070] S5: Create a height cross-section parameter relationship: According to the ratio of the cross-section inertia moment n2 of the middle cross-beam and the column, obtain the cross-section parameter design relationship of the middle cross-beam profile; 中_横梁 =n2·I 立柱

[0071] The height layout position of the middle cross beam of the ROPS frame is determined according to the middle cross beam optimal height dimension relationship, and the profiles of the middle cross beam and the corresponding columns are selected according to the middle cross beam profile section parameter design relationship.

[0072] The optimal center crossbeam height and dimension relationship equations are related to the ROPS frame's external dimensions and are inherent properties of the ROPS frame. These equations guide the optimal design of the center crossbeam for this ROPS frame. The design method of the present invention can be used to statistically summarize the external dimensions of common aircraft models and create a database of optimal design equations for a full-cab ROPS frame.

[0073] Example 3

[0074] A cab for engineering machinery includes the ROPS frame described in Example 1 and is designed using the crossbeam optimization design method for the ROPS frame described in Example 2.

[0075] In practical applications, the length dimension W of the middle cross beam (W takes a value of 1.45m to 1.6m) is the width dimension of the cab. In the portal frame-type statically indeterminate structural mechanics model simplified to a simply supported beam, since the simply supported beam has no width, the width dimension of the cab is replaced by the length dimension W of the middle cross beam.

[0076] The engineering machinery may be a hydraulic excavator, a loader, a road roller, a motor grader, etc., and has the advantages of the ROPS skeleton provided by the embodiment of the present disclosure.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for optimizing the crossbeam design of a central axis symmetrical ROPS frame, characterized in that: The central axis symmetrical ROPS skeleton includes columns, cross beams, and longitudinal beams; the columns include A-pillars, B-pillars, and D-pillars; the cross beams include top cross beams, middle cross beams, and bottom cross beams; the longitudinal beams include top longitudinal beams and bottom longitudinal beams; the two A-pillars are connected by a first top cross beam and a first bottom cross beam to form a closed rectangular A ring; the two B-pillars are connected by a second top cross beam and a second bottom cross beam to form a closed rectangular B ring; the two D-pillars are connected by a third top cross beam and a third bottom cross beam to form a closed rectangular D ring; the two ends of the middle cross beam are respectively connected to the inner sides of the middle parts of the two D-pillars, and the third top cross beam, the middle cross beam, and the third bottom cross beam are arranged in parallel; the four corners corresponding to the A ring and the B ring are connected by the first top longitudinal beam and the first bottom longitudinal beam, and the four corners corresponding to the B ring and the D ring are connected by the second top longitudinal beam and the second bottom longitudinal beam to form a closed space frame structure; the method includes: According to the ROPS skeleton structure, extract the length dimension W of the center beam, the length dimension L of the D column and the height dimension L of the center beam d , forming a portal-type statically indeterminate structural mechanics model; The height dimension L of the middle crossbeam is obtained based on the ROPS test data. d It can affect the lateral load capacity of ROPS and select the height dimension L of the middle beam. d As the design parameter of the ROPS skeleton structure; the section inertia moment I of the profile is the key factor that determines the bending moment distribution in the mechanical model, so the section inertia moment I of the profile is selected as the design parameter of the profile; The structural mechanics analysis software is used to analyze the bending moment stress value of the portal type statically indeterminate structural mechanics model and obtain the maximum bending moment Max (M 立柱底 , M 立柱中 )The minimum height dimension L of the middle crossbeam d , thus obtaining the height dimension L of the middle beam d The ratio n1 of the length dimension L of the D-pillar; The structural mechanics analysis software is used to analyze the bending moment stress value of the portal frame type statically indeterminate structural mechanics model and obtain the height dimension L of the beam. d When the optimal height dimension is adopted and the maximum bending moment stress of the cross beam and the column in the ROPS frame is equal, the ratio of the section inertia moment of the center cross beam to the D-pillar is n2, and the value range of n2 is 1.15 to 1.45; According to the height dimension L of the middle crossbeam d The ratio n1 of the length dimension L of the D-pillar is used to obtain the optimal height dimension relationship of the center crossbeam; According to the ratio of the cross-sectional inertia moment n2 between the center cross-section beam and the D-pillar, the design relationship of the cross-sectional parameters of the center cross-section beam is obtained; The height layout position of the middle cross beam of the ROPS frame is determined according to the middle cross beam optimal height dimension relationship, and the profiles of the middle cross beam and the corresponding columns are selected according to the middle cross beam profile section parameter design relationship.

2. The crossbeam optimization design method for a ROPS frame according to claim 1, characterized in that: The length dimension W of the center cross beam is 1.45m to 1.6m; the length dimension L of the D-pillar is 1.65m to 1.9m.

3. The crossbeam optimization design method for a ROPS frame according to claim 1, characterized in that: The optimal height dimension relationship of the middle crossbeam is: L d = n1·L.

4. The method for optimizing the design of crossbeams in a ROPS frame according to claim 1 or 3, characterized in that: The value range of n1 is 0.45~0.

55.

5. The method for optimizing the design of crossbeams in a ROPS frame according to claim 1, characterized in that: The design relationship of the cross-beam profile section parameters is: 中_横梁 = n2·I 立柱 .

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