阅读说明：本技术 一种倒角刀具加工纤维增强复合材料毛刺长度预测方法 (Method for predicting burr length of fiber reinforced composite material machined by chamfering tool ) 是由 康仁科 董志刚 田俊超 刘志强 鲍岩 朱祥龙 高尚 于 2019-10-12 设计创作，主要内容包括：本发明一种倒角刀具加工纤维增强复合材料毛刺长度预测方法,属于复合材料加工技术领域。该方法在实施过程中首先对倒角刀具几何尺寸及形状轮廓数据进行测量,并建立刀具-工件轮廓几何模型,在此基础上计算纤维排布面内倒角刀具楔角,结合切出侧纤维方向角建立纤维排布面内刀具-纤维相互作用几何模型,在此基础上确定未断裂纤维首次发生断裂的位置并计算毛刺长度。本方法根据纤维增强复合材料毛刺产生机理,建立倒角刀具加工纤维增强复合材料产生毛刺长度的预测模型,方法涉及内容全面、完整,易于操作。(The invention discloses a method for predicting the burr length of a fiber reinforced composite material machined by a chamfering tool, and belongs to the technical field of composite material machining. In the implementation process, firstly, the geometrical size and shape profile data of the chamfering tool are measured, a tool-workpiece profile geometrical model is established, the wedge angle of the chamfering tool in the fiber arrangement surface is calculated on the basis, the tool-fiber interaction geometrical model in the fiber arrangement surface is established by combining the cut-out side fiber direction angle, the position where the unbroken fibers are broken for the first time is determined on the basis, and the burr length is calculated. The method establishes a prediction model of the length of the burrs generated when the chamfering tool processes the fiber reinforced composite material according to the burr generation mechanism of the fiber reinforced composite material, and is comprehensive and complete in related content and easy to operate.)

1. A method for predicting the burr length of a fiber reinforced composite material machined by a chamfering tool is characterized by comprising the following steps:

measuring the geometrical size and shape profile data of the chamfering tool;

establishing a tool-workpiece outline geometric model based on the relative position relationship between the chamfering tool and the workpiece to be processed, and defining a cutting-out angle phi of the chamfering tool to describe the tool-workpiece relative position relationship in the tool-workpiece outline geometric model, wherein the cutting-out angle phi is specified to be an acute angle;

calculating a wedge angle beta' of the chamfering tool in the fiber arrangement surface based on the cut-out angle phi and the geometrical size and shape profile data measurement value of the chamfering tool, establishing a tool-fiber interaction geometrical model in the fiber arrangement surface by combining the cut-out side fiber direction angle theta, and determining the position of the first fracture of the non-fractured fiber;

based on the position of the first rupture of the unbroken fiber, the combination of the cut-out side fiber direction angle theta and the axial cutting depth a of the chamfering tool_pMaximum theoretical burr length l for machining workpiece to be machined by chamfering tool_bCalculating and recording_bAnd (4) predicting the burr length.

2. The method of claim 1, wherein: the relative position relationship between the chamfering tool and the workpiece to be machined refers to:

in the processing process, the axis of the chamfering tool is parallel to the fiber cloth arranging surface of the workpiece to be processed:

when the workpiece to be processed is a plane component, the fiber arrangement surface of the workpiece is superposed on the cut wall plane of the plane component;

when the workpiece to be processed is a curved surface component, the fiber arrangement surface of the workpiece is a wall cutting plane cut out of the curved surface component, and the cutting plane passes through a cutting point;

the establishment of the tool-workpiece contour geometric model refers to the following steps:

projecting along the axial direction of the chamfering tool, wherein the contour of the chamfering tool is a circle, the cut wall contour of the workpiece to be machined is a curve, and the two are in an intersection relationship in the cutting process, so that a tool-workpiece contour geometric model is obtained;

the cutting angle phi is as follows:

the included angle between the cutting direction of the cutting point chamfering tool and the cut wall profile of the workpiece to be processed is formed;

when the cut wall of the workpiece to be processed is a straight line, the cut angle phi is an included angle between the cutting direction of the cut point cutter and the cut wall of the workpiece to be processed;

when the cut-out wall of the workpiece to be processed is a curve, the cut-out angle phi is an included angle between the cutting direction of the cut-out point cutter and the cut-out wall profile tangent of the workpiece to be processed, and the tangent passes through a cut-out point;

and, the cutting angle phi satisfies the following formula:

wherein: l is the distance between the axis of the chamfering tool and the cut wall of the workpiece to be processed or the tangent line of the cut wall profile, r_sIs the radius of the end face of the chamfering tool.

3. The method of claim 2, wherein: the calculation process of the wedge angle beta' of the chamfering tool in the fiber arrangement surface is as follows:

according to the measured values of the geometric dimension and the shape profile of the chamfering tool, the chamfer angle beta of the tool is recorded, and the chamfer length b of the tool is recorded_∈The chamfering method comprises the following steps of obtaining data of one side of a chamfering tool entity, wherein the tool chamfering is an included angle between a tool end face contour line and an adjacent chamfering bevel contour line in a chamfering tool axial cross-section, and the tool chamfering length is the length of the chamfering bevel contour line in the chamfering tool axial cross-section;

based on the cutting angle phi, combining the chamfer angle beta of the cutter and the radius r of the end surface of the cutter_sCalculating the cutting wedge angle beta' in the fiber arrangement surface:

when the cutter chamfer angle beta is an acute angle, the chamfer cutter wedge angle beta' in the fiber arrangement surface is as follows:

when the cutter chamfer angle beta is an obtuse angle, the chamfer cutter wedge angle beta' in the fiber arrangement surface is as follows:

the cut side fiber direction angle theta is an angle rotated by the chamfering tool from anticlockwise rotation in the feeding direction to be parallel to the fiber direction;

recording the end surface inflection point as the intersection point of the end surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line, and recording the side surface inflection point as the intersection point of the side surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line;

establishing a cutter-fiber interaction geometric model in a fiber arrangement plane, and determining the position of the first fracture of the unbroken fibers, wherein the method comprises the following steps:

a. when the beta' < (pi-theta), the unbroken fibers firstly contact with the end face inflection point, and the unbroken fibers are broken at the end face inflection point for the first time;

b. when β' ≧ (π - θ), the unbroken fibers first contact the lateral inflection point, at which the unbroken fibers first break.

4. The method of claim 3, wherein:

when the unbroken fibers are broken at the inflection point of the end face for the first time, the maximum length l of the theoretical burr_bComprises the following steps:

l_b＝0

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pAt greater time, i.e. a_p≥b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps:

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pSmaller, i.e. a_p<b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps:

Technical Field

The invention belongs to the technical field of composite material processing, and particularly relates to a method for predicting the burr length of a fiber reinforced composite material processed by a chamfering tool.

Background

The composite material is a novel material formed by combining two or more materials through a composite process, not only can retain the main characteristics of the original components, but also can ensure that the performances of the components are mutually supplemented and are mutually associated and cooperated through material design, thereby obtaining the superior performances which are not possessed by the raw materials, having the advantages of high specific strength and specific rigidity, high temperature resistance and the like, and being widely applied in the fields of aerospace, energy, chemical industry and the like. The fiber reinforced composite material is a typical composite material, takes fiber as a reinforcing phase, takes metal, ceramic or polymer resin as a matrix phase, and is a composite material with wider application.

The fiber reinforced composite material has typical anisotropy, has larger difference of mechanical properties in different directions, and can obtain more ideal mechanical and service properties by usually interlacing fibers to prepare a laminated plate for use. However, the fiber reinforced composite material member cannot be directly formed, and the member blank needs to be subjected to secondary machining to enable the member to obtain the dimension and the precision meeting the design requirements. Due to the fact that the anisotropy of the composite material and the strength of a fiber-matrix interface are low, the reinforcing phase and the matrix phase are alternately removed in the machining process, the removing process is unstable, the problems of serious cutter abrasion, machined surface defects and the like are prone to occurring, and machining cost, service performance of the member and service life of the member are seriously affected.

In order to increase the strength of the tool and prolong the service life of the tool, a chamfer is often arranged at the transition position of the end face and the side face of the tool, and although the measure can prolong the service life of the tool to a certain extent, the defect of the processed surface of the composite material cannot be inhibited. The burr is a typical machined defect, and the generation mechanism of the burr is that the fiber is deformed by the cutter under the action of cutting force and does not break in the machining process, the fiber protrudes from the machined surface after machining is finished, the overlong burr can influence the assembly quality and reduce the assembly reliability, and if the burr breaks in the use process and enters some important structures, the use performance of the mechanism can be influenced, and even serious safety accidents are caused by danger. Therefore, a burr size correlation model is established, the burr lengths under different process conditions are predicted, the selection of process parameters and the control of the burr sizes are facilitated, and the processing quality of workpieces is guaranteed.

There are models related to burr size prediction, such as hintz W, Hartmann D, Sch ü ttec. occurrence and propagation of propagation degradation of the Carbon Fiber Reinforced Plastics (CFRPs) -An experimental study [ J ] Composites science and Technology,2011,71(15): 1719-.

Disclosure of Invention

The invention aims to provide a method for predicting the length of burrs on a machined surface aiming at the burr defects in the machining process of a fiber reinforced composite material.

The technical solution for realizing the purpose of the invention is as follows:

a method for predicting the burr length of a fiber reinforced composite material machined by a chamfering tool comprises the following steps:

measuring the geometrical size and shape profile data of the chamfering tool;

establishing a tool-workpiece outline geometric model based on the relative position relationship between the chamfering tool and the workpiece to be processed, and defining a cutting-out angle phi of the chamfering tool to describe the tool-workpiece relative position relationship in the tool-workpiece outline geometric model, wherein the cutting-out angle phi is specified to be an acute angle;

calculating a wedge angle beta' of the chamfering tool in the fiber arrangement surface based on the cut-out angle phi and the geometrical size and shape profile data measurement value of the chamfering tool, establishing a tool-fiber interaction geometrical model in the fiber arrangement surface by combining the cut-out side fiber direction angle theta, and determining the position of the first fracture of the non-fractured fiber;

based on the position of the first rupture of the unbroken fiber, the combination of the cut-out side fiber direction angle theta and the axial cutting depth a of the chamfering tool_pMaximum theoretical burr length l for machining workpiece to be machined by chamfering tool_bCalculating and recording_bAnd (4) predicting the burr length.

The relative position relationship between the chamfering tool and the workpiece to be machined refers to:

in the processing process, the axis of the chamfering tool is parallel to the fiber cloth arranging surface of the workpiece to be processed:

when the workpiece to be processed is a plane component, the fiber arrangement surface of the workpiece is superposed on the cut wall plane of the plane component;

when the workpiece to be processed is a curved surface component, the fiber arrangement surface of the workpiece is a wall cutting plane cut out of the curved surface component, and the cutting plane passes through a cutting point;

the establishment of the tool-workpiece contour geometric model refers to the following steps:

projecting along the axial direction of the chamfering tool, wherein the contour of the chamfering tool is a circle, the cut wall contour of the workpiece to be machined is a curve, and the two are in an intersection relationship in the cutting process, so that a tool-workpiece contour geometric model is obtained;

the cutting angle phi is as follows:

the included angle between the cutting direction of the cutting point chamfering tool and the cut wall profile of the workpiece to be processed is formed;

when the cut wall of the workpiece to be processed is a straight line, the cut angle phi is an included angle between the cutting direction of the cut point cutter and the cut wall of the workpiece to be processed;

when the cut-out wall of the workpiece to be processed is a curve, the cut-out angle phi is an included angle between the cutting direction of the cut-out point cutter and the cut-out wall profile tangent of the workpiece to be processed, and the tangent passes through a cut-out point;

and, the cutting angle phi satisfies the following formula:

wherein: l is the distance between the axis of the chamfering tool and the cut wall of the workpiece to be processed or the tangent line of the cut wall profile, r_sIs the radius of the end face of the chamfering tool.

The calculation process of the cutting wedge angle beta' of the chamfering tool in the fiber arrangement surface is as follows:

according to the measured values of the geometric dimension and the shape profile of the chamfering tool, the chamfer angle beta of the tool is recorded, and the chamfer length b of the tool is recorded_∈The chamfering method comprises the following steps of obtaining data of one side of a chamfering tool entity, wherein the tool chamfering is an included angle between a tool end face contour line and an adjacent chamfering bevel contour line in a chamfering tool axial cross-section, and the tool chamfering length is the length of the chamfering bevel contour line in the chamfering tool axial cross-section;

based on the cutting angle phi, combining the chamfer angle beta of the cutter and the radius r of the end surface of the cutter_sCalculating the cutting wedge angle beta' in the fiber arrangement surface:

when the cutter chamfer angle beta is an acute angle, the chamfer cutter wedge angle beta' in the fiber arrangement surface is as follows:

when the cutter chamfer angle beta is an obtuse angle, the chamfer cutter wedge angle beta' in the fiber arrangement surface is as follows:

the cut side fiber direction angle theta is an angle rotated by the chamfering tool from anticlockwise rotation in the feeding direction to be parallel to the fiber direction;

recording the end surface inflection point as the intersection point of the end surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line, and recording the side surface inflection point as the intersection point of the side surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line;

establishing a cutter-fiber interaction geometric model in a fiber arrangement plane, and determining the position of the first fracture of the unbroken fibers, wherein the method comprises the following steps:

a. when the beta' < (pi-theta), the unbroken fibers firstly contact with the end face inflection point, and the unbroken fibers are broken at the end face inflection point for the first time;

b. when β' ≧ (π - θ), the unbroken fibers first contact the lateral inflection point, at which the unbroken fibers first break.

When the unbroken fibers are broken at the inflection point of the end face for the first time, the maximum length l of the theoretical burr_bComprises the following steps:

l_b＝0

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pAt greater time, i.e. a_p≥b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps:

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pSmaller, i.e. a_p<b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps:

the invention has the beneficial effects that: the invention provides a burr length prediction method, which is based on a geometrical model of interaction between a cutting wedge angle in a cutting plane and unbroken fibers, can master the characteristics of the processing defects of a fiber reinforced composite material on the basis of a small-batch experiment, greatly saves the cost of a cutter and materials in the experiment process, can supplement and perfect burr length prediction model systems under different working conditions, can provide a basis for designing a processing cutter, is beneficial to the quality control of the processed surface of the composite material, and provides technical support for the high-quality and high-efficiency processing of the composite material.

Based on the reasons, the invention can be widely popularized in the fields of composite material processing technology and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a tool-workpiece contour geometric model.

FIG. 2 is a geometric model of the chamfer tool-fiber interaction when the tool chamfer is an acute angle.

FIG. 3 is a chamfer tool-fiber interaction geometric model for a tool chamfer at an obtuse angle.

FIG. 4 is a schematic diagram of relevant dimensions of a chamfer grinding wheel geometry.

FIG. 5 is a line graph comparing an experimental value of burrs on a machined surface with a predicted value of the present invention under different process parameters when a chamfer tool is used for machining a fiber-reinforced composite material.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A method for predicting the burr length of a fiber reinforced composite material machined by a chamfering tool comprises the following steps:

measuring the geometrical size and shape profile data of the chamfering tool;

establishing a tool-workpiece outline geometric model based on the relative position relationship between the chamfering tool and the workpiece to be processed, and defining a cutting-out angle phi of the chamfering tool to describe the tool-workpiece relative position relationship in the tool-workpiece outline geometric model, wherein the cutting-out angle phi is specified to be an acute angle;

the relative position relationship between the chamfering tool and the workpiece to be machined refers to:

in the processing process, the axis of the chamfering tool is parallel to the fiber cloth arranging surface of the workpiece to be processed:

when the workpiece to be processed is a plane component, the fiber arrangement surface of the workpiece is superposed on the cut wall plane of the plane component; when the workpiece to be machined is a planar member, a geometric model of the tool-workpiece contour, as shown in fig. 1, where f is a feed amount for representing a feed direction, and a cut-out point position is determined in conjunction with a tool rotation direction.

When the workpiece to be processed is a curved surface component, the fiber arrangement surface of the workpiece is a wall cutting plane cut out of the curved surface component, and the cutting plane passes through a cutting point;

the establishment of the tool-workpiece contour geometric model refers to the following steps:

projecting along the axial direction of the chamfering tool, wherein the contour of the chamfering tool is a circle, the cut wall contour of the workpiece to be machined is a curve, and the two are in an intersection relationship in the cutting process, so that a tool-workpiece contour geometric model is obtained;

the cutting angle phi is as follows:

the included angle between the cutting direction of the cutting point chamfering tool and the cut wall profile of the workpiece to be processed is formed;

when the cut wall of the workpiece to be processed is a straight line, the cut angle phi is an included angle between the cutting direction of the cut point cutter and the cut wall of the workpiece to be processed;

when the cut-out wall of the workpiece to be processed is a curve, the cut-out angle phi is an included angle between the cutting direction of the cut-out point cutter and the cut-out wall profile tangent of the workpiece to be processed, and the tangent passes through a cut-out point;

and, the cutting angle phi satisfies the following formula:

wherein: l is the distance between the axis of the chamfering tool and the cut wall of the workpiece to be processed or the tangent line of the cut wall profile, r_sIs the radius of the end face of the chamfering tool.

Calculating a wedge angle beta' of the chamfering tool in the fiber arrangement surface based on the cut-out angle phi and the geometrical size and shape profile data measurement value of the chamfering tool, establishing a tool-fiber interaction geometrical model in the fiber arrangement surface by combining the cut-out side fiber direction angle theta, and determining the position of the first fracture of the non-fractured fiber;

the calculation process of the cutting wedge angle beta' of the chamfering tool in the fiber arrangement surface is as follows:

according to the measured values of the geometric dimension and the shape profile of the chamfering tool, the chamfer angle beta of the tool is recorded, and the chamfer length b of the tool is recorded_∈The chamfering method comprises the following steps of obtaining data of one side of a chamfering tool entity, wherein the tool chamfering is an included angle between a tool end face contour line and an adjacent chamfering bevel contour line in a chamfering tool axial cross-section, and the tool chamfering length is the length of the chamfering bevel contour line in the chamfering tool axial cross-section;

based on the cutting angle phi, combining the chamfer angle beta of the cutter and the radius r of the end surface of the cutter_sCalculating the cutting wedge angle beta' in the fiber arrangement surface:

as shown in fig. 2, when the cutter chamfer β is an acute angle, the chamfer cutter wedge angle β' in the fiber arrangement plane is:

as shown in fig. 3, when the cutter chamfer β is an obtuse angle, the chamfer cutter wedge angle β' in the fiber arrangement plane is:

as the cutting angle phi gradually approaches 0 DEG, the cutting wedge angle beta' approaches 90 DEG;

the cut side fiber direction angle theta is an angle rotated by the chamfering tool from anticlockwise rotation in the feeding direction to be parallel to the fiber direction;

recording the end surface inflection point as the intersection point of the end surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line, and recording the side surface inflection point as the intersection point of the side surface contour line of the cutter in the fiber arrangement surface and the chamfer inclined surface contour line;

establishing a cutter-fiber interaction geometric model in a fiber arrangement plane, and determining the position of the first fracture of the unbroken fibers, wherein the method comprises the following steps:

a. when the beta' < (pi-theta), the unbroken fibers firstly contact with the end face inflection point, and the unbroken fibers are broken at the end face inflection point for the first time;

b. when β' ≧ (π - θ), the unbroken fibers first contact the lateral inflection point, at which the unbroken fibers first break.

Based on the position of the first rupture of the unbroken fiber, the combination of the cut-out side fiber direction angle theta and the axial cutting depth a of the chamfering tool_pMaximum theoretical burr length l for machining workpiece to be machined by chamfering tool_bCalculating and recording_bFor burr length prediction:

when the unbroken fibers are broken at the inflection point of the end face for the first time, the maximum length l of the theoretical burr_bComprises the following steps:

l_b＝0

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pAt greater time, i.e. a_p≥b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps:

when the unbroken fiber is broken at the side inflection point at first, and the axial cutting depth a of the chamfering tool_pSmaller, i.e. a_p<b_∈Sin beta, maximum theoretical spur length l_bComprises the following steps: