CN114425710A

CN114425710A - System and method for high-quality drilling of composite through hole

Info

Publication number: CN114425710A
Application number: CN202210263218.0A
Authority: CN
Inventors: 史振宇; 邵国栋; 王兆辉; 袭建人; 杨晓涛
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2022-03-17
Filing date: 2022-03-17
Publication date: 2022-05-03

Abstract

The invention discloses a system and a method for drilling a composite through hole with high quality, belonging to the technical field of machining of difficult-to-machine materials, and comprising the following steps: the clamp device comprises a first clamp body and a second clamp body which are horizontally arranged oppositely, and the first clamp body and the second clamp body clamp the workpiece from two sides; the drilling device comprises a first drilling tool and a second drilling tool which are oppositely arranged from top to bottom, wherein the first drilling tool feeds downwards to drill the upper half part of the through hole in the workpiece, and the second drilling tool feeds upwards to drill the lower half part of the through hole in the workpiece.

Description

System and method for high-quality drilling of composite through hole

Technical Field

The invention belongs to the technical field of machining of difficult-to-machine materials, and particularly relates to a system and a method for drilling a composite through hole with high quality.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

At present, composite materials are widely applied to national defense industries such as aerospace and the like, and comprise carbon fiber composite materials, aramid fiber composite materials, glass fiber composite materials and the like. Since the aerospace industry commonly uses riveting to assemble parts, a large number of through-hole features need to be machined.

The inventor finds that the through hole is generally processed in a drilling mode, but the composite material is generally a non-homogeneous material, has high hardness and is difficult to cut, and during the process of drilling the through hole of the composite material, a drilling tool is seriously abraded, and a hole outlet is easy to generate serious processing defects, such as burrs, fiber tearing, delamination, matrix peeling and the like. The processing defects seriously affect the processing quality of the workpiece and even lead to the scrapping of the workpiece, thereby bringing great economic loss.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a system and a method for drilling a composite through hole with high quality.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, the present invention provides a system for high quality drilling of composite through holes, comprising:

the clamp device comprises a first clamp body and a second clamp body which are horizontally arranged oppositely, and the first clamp body and the second clamp body clamp the workpiece from two sides;

the drilling device comprises a first drilling tool and a second drilling tool which are oppositely arranged from top to bottom, the first drilling tool feeds downwards to drill the upper half part of the through hole in the workpiece, and the second drilling tool feeds upwards to drill the lower half part of the through hole in the workpiece.

As a further technical scheme, the first clamp body and the second clamp body are arranged on the same horizontal plane and are opposite and spaced.

As a further technical solution, the first and second clamp bodies may be movable.

As a further technical scheme, the first clamp body and the second clamp body are both of a C-shaped structure.

As a further technical scheme, the C-shaped openings of the first clamp body and the second clamp body are arranged oppositely, and the first clamp body and the second clamp body clamp the workpiece from two sides of the workpiece.

As a further technical scheme, the first drilling tool and the second drilling tool are vertically arranged, the first drilling tool is connected with the first main shaft, and the second drilling tool is connected with the second main shaft.

As a further technical scheme, the device also comprises a positioning device, wherein the positioning device comprises a positioning tool, and the positioning tool is fixed on the side part of the workpiece to determine the coordinates of the workpiece.

As a further technical scheme, the numerical control device and the chip cleaning device are further included, the numerical control device is connected with the drilling device, the chip cleaning device comprises a negative pressure absorption device, and the negative pressure absorption device is provided with a pipeline extending to a workpiece machining position.

In a second aspect, the present invention also provides a method for machining a through hole by using the system for high quality drilling of composite through holes as described above, comprising the steps of:

fixing a composite material workpiece to be processed on a fixture device, and horizontally moving the fixture device to clamp the workpiece;

carrying out coordinate positioning on a composite material workpiece to be processed by utilizing a positioning device;

in the drilling process, a first drilling tool of the drilling device drills a hole downwards from the upper surface of the composite material workpiece, and the set hole depth is drilled to machine the upper half part of the through hole; and then a second drilling tool of the drilling device drills holes upwards from the lower surface of the composite material workpiece, and the residual hole depth is drilled to machine the lower half part of the through hole.

As a further technical scheme, in the drilling process, a numerical control device is utilized to determine the coordinates of the hole to be processed of the composite material workpiece, set drilling parameters and control the drilling process; chips produced by the drilling process are cleaned with a chip cleaning device.

The beneficial effects of the invention are as follows:

according to the system, the drilling device is provided with the two drilling tools which are opposite up and down, one drilling tool feeds downwards to drill the upper half part of the through hole, the other drilling tool feeds upwards to drill the lower half part of the through hole, the through hole is not formed at one time, better hole outlet machining appearance can be obtained through sequential drilling in the up and down directions, and the defects of fiber tearing, layering, stripping, edge breakage and the like at the hole outlet are effectively avoided.

According to the system, the clamp device is provided with the two clamp bodies which are opposite in the horizontal direction, and the two clamp bodies clamp the workpiece on two sides of the workpiece, so that the interference with the movement of the drilling device can be avoided.

According to the method, one part of the through hole deep processing through hole is drilled vertically downwards, and then the other part of the through hole deep processing through hole is drilled vertically upwards, so that damage of the composite material workpiece caused by one-time drilling is changed, the good processing appearance of the hole outlet is ensured, the damage degree of the hole outlet is reduced, and the drilling processing quality of the composite material through hole is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are included to illustrate an exemplary embodiment of the invention and not to limit the invention.

FIG. 1 is a schematic view of a system for high quality drilling of composite through holes according to one or more embodiments of the present invention;

FIG. 2(a) is a schematic view of the two clamp bodies of the clamp apparatus as they are disengaged from the workpiece;

FIG. 2(b) is a schematic view of the two clamp bodies of the clamp device when clamping a workpiece;

FIG. 3(a) is a schematic view of a numerically controlled positioning of a first drill tool during machining of a workpiece;

FIG. 3(b) is a schematic view of the numerically controlled positioning of a second drill tool in machining a workpiece;

FIG. 4(a) is a schematic view of a first drill tool machining an upper half of a through-hole in a workpiece;

FIG. 4(b) is a schematic view when the second drilling tool is used for machining a non-through hole in the lower half of the through hole of the workpiece;

FIG. 4(c) is a schematic view showing a second drilling tool for machining the lower half portion of the through hole of the workpiece to complete the through hole machining;

FIG. 5(a) is a graph of the topography of the upper surface holes of the workpiece of example one;

FIG. 5(b) is the topography of the lower surface holes of the workpiece of example one;

FIG. 6(a) is the topography of the upper surface holes of the workpiece of example two;

FIG. 6(b) is the topography of the lower surface holes of the workpiece of example two;

in the figure: the mutual spacing or size is exaggerated to show the position of each part, and the schematic diagram is only used for illustration;

wherein, 1-a first main shaft; 2-a first drilling tool; 3-a composite workpiece; 4-a second drilling tool; 5-a second spindle; 6-a clamping device; 61-a first gripper body; 62-a second clamp body; 7-a positioning device; 8-a chip cleaning device; 9-numerical control device.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In an exemplary embodiment of the invention, as shown in fig. 1, a system for high quality drilling of through holes in composite materials is proposed, which comprises a clamping device 6, a positioning device 7, a numerical control device 9, a drilling device, and a chip cleaning device 8.

The fixture device 6 is used for fixing a workpiece, and the fixture device clamps and fixes the workpiece from the left side and the right side of the workpiece; the positioning devices 7 are disposed on both sides of the workpiece, and perform coordinate positioning on the workpiece.

The fixture device 6 has the function of clamping a workpiece to be machined and fixing the position of the workpiece. The clamp device 6 comprises a first clamp body 61 and a second clamp body 62, wherein the first clamp body 61 and the second clamp body 62 are arranged on the same horizontal plane and are opposite and spaced; the first clamp body 61 and the second clamp body 62 clamp the workpiece from two sides, so that the clamping is reliable, and the vertical movement of the drilling tool cannot be hindered.

In this embodiment, the first clamp body and the second clamp body are both of a C-shaped structure, C-shaped openings of the first clamp body and the second clamp body are oppositely arranged, and the first clamp body and the second clamp body clamp and clamp a workpiece from two sides of the workpiece; the principle of clamping the workpiece by the first clamp body and the second clamp body is similar to that of clamping by a pressing plate and clamping by flat tongs.

In a preferred embodiment, the first and

second clamp bodies

61 and 62 are movable, and the movement thereof can be driven by a linear reciprocating mechanism, such as a hydraulic cylinder, a lead screw slider mechanism, a rack and pinion mechanism, etc., as long as the first and second clamp bodies are driven to translate.

In the system, the clamp device is arranged into two parts which are separated from the left and the right, and the clamp is not arranged into a whole any more, because the workpiece needs to be processed in the vertical direction in the drilling process, the clamp device cannot interfere with the movement of the drilling device; and the two parts of the clamp device 6 are horizontally moved to reasonable positions according to the size and the shape of the workpiece and fixed at specific positions, so that different workpieces can be clamped, and interference on drilling devices for up-and-down processing can be avoided.

The positioning device 7 is used for coordinate positioning of the workpiece. The positioning device 7 measures the position of the workpiece, measures the datum point of the workpiece and determines the coordinates of the workpiece; the positioning device comprises a positioning tool, the positioning tool is fixed on the side part of the workpiece, and the positioning tool can adopt equipment such as an edge finder and the like; the working principle is that the edge finder is utilized to measure the coordinates of a workpiece, and the method specifically comprises the following steps: measuring an X-direction coordinate X0 (an absolute coordinate system) of the workpiece through an edge finder, measuring a Y-direction coordinate Y0 (the absolute coordinate system) through the edge finder, and regarding (X0, Y0) as a reference point of the workpiece; the datum point (x0, y0) is the origin (0, 0) of a workpiece coordinate system (relative coordinate system), and then a numerical control program is written by a numerical control device according to the datum point (0, 0) so as to control the action of the drilling device, wherein the position movement of the upper part and the lower part of the drilling device is based on the datum point.

The drilling device is used for drilling composite materials. The drilling device comprises a first drilling tool 2 and a second drilling tool 4 which are arranged oppositely up and down, wherein the first drilling tool is positioned above the workpiece, and the workpiece can be drilled by feeding downwards to machine the upper half part of the through hole; the second drilling cutter is located the work piece below, and the upfeed can carry out the drilling to the work piece, the latter half of processing through-hole, and the processing that can realize the work piece through-hole after two drilling cutters carry out the drilling to the work piece.

First drilling cutter, the equal vertical setting of second drilling cutter, first drilling cutter and 1 connection of first main shaft, second drilling cutter and 5 connections of second main shaft, first main shaft, second main shaft all have XYZ direction three degrees of freedom, and it can drive the drilling cutter and reciprocate and rotate.

The working principle of the drilling device is as follows: as shown in fig. 4(a), the first main shaft moves to above the hole to be processed, the first main shaft drives the first drilling tool to start processing from the upper surface of the composite material workpiece, the feeding direction of the first drilling tool is vertical downward, the feeding is stopped when the first drilling tool drills to a certain hole depth (for example, 1/2 of the depth of the through hole), and then the first drilling tool returns to the original position;

as shown in fig. 4(b) and 4(c), the second main shaft moves to the position below the hole to be processed, the second main shaft drives the second drilling tool to start processing from the lower surface of the composite material workpiece, the feeding direction of the second drilling tool is vertical upward, the rest hole depth is drilled, and then the second drilling tool returns to the original position.

In fig. 3(a) -3 (b), the numerically controlled positioning of high quality drilled composite through holes is illustrated, as explained in detail below:

as shown in fig. 3(a), the first main shaft and the first drilling tool are in the initial position, and the coordinates are (0, 0); a numerical control program in the numerical control device controls the first main shaft and the first drilling tool to move above the hole to be processed, and the coordinates are (x1, y 1); according to the set main shaft rotating speed, the set feeding speed and the set feeding distance, the first main shaft and the first drilling tool start drilling from the upper surface of the composite material workpiece, and the direction is vertical downwards; after completing the set drilling task, the first main shaft and the first drilling tool return to the (x1, y1) position; circularly reciprocating until all through holes are drilled;

as shown in fig. 3(b), the second main shaft and the second drilling tool are in the initial position, and the coordinates are (0, 0); a numerical control program in the numerical control device controls the second main shaft and the second drilling tool to move below the hole to be machined, and the coordinates are (x1, y 1); according to the set main shaft rotating speed, the set feeding speed and the set feeding distance, a second main shaft and a second drilling tool start drilling from the lower surface of the composite material workpiece, and the direction is vertically upward; after completing the set drilling task, the second main shaft and the second drilling tool return to the (x1, y1) position; and repeating the steps until all through holes are drilled.

The numerical control device 9 serves to control the drilling process. The numerical control device 9 sets drilling parameters and a drilling path and controls the drilling process; the working principle is that according to the processing requirements, the feeding action of the drilling tool is controlled by a corresponding numerical control program so as to control the drilling process.

The chip cleaning device 8 is arranged above or below the workpiece, and can clean chips generated in the drilling process in the machining process and reduce the negative influence caused by the chips. The chip cleaning device comprises a negative pressure absorption device, a pipeline of the negative pressure absorption device extends to a workpiece machining position, air generates negative pressure by utilizing high-speed rotation of a motor, chips generated by drilling are absorbed by the air negative pressure according to the atmospheric pressure principle, and the absorbed chips are finally stored in a chip storage box.

Example 2

In this embodiment, a method for processing a through hole by the system described above is provided, and the method includes the following specific operation steps:

the method comprises the following steps: fixing a composite material workpiece 3 to be processed on a clamp device 6, and horizontally moving the clamp device 6 to clamp the workpiece;

step two: carrying out coordinate positioning on the composite material workpiece 3 to be processed by using a positioning device 7;

step three: determining the coordinates of the hole to be processed of the composite material workpiece 3 by using a numerical control device 9, setting specific drilling parameters and controlling the drilling process;

step four: drilling a hole downwards from the upper surface of the composite material workpiece 3 using the first drilling tool 2 of the drilling device, this step drilling only a part of the hole depth (for example 1/2 hole depth);

step five: drilling a hole upwards from the lower surface of the composite material workpiece 3 by using a second drilling tool 4 of the drilling device, wherein the residual hole depth is drilled;

step six: and cleaning the chips generated in the drilling process by using a chip cleaning device 8, wherein the step is synchronously performed with the fourth step and the fifth step.

The system and the method can be applied to the drilling processing of various composite materials, including aramid fiber composite materials, carbon fiber composite materials, glass fiber composite materials, silicon carbide fiber composite materials and the like.

The effect of the system is described below with reference to a specific example, wherein, the example is a comparison group, and composite through holes are drilled by using the prior art; the second example is an experimental group, and the system and the method of the scheme are utilized to drill the through holes of the composite material.

The first embodiment is as follows: drilling through holes of the composite material by using the prior art;

in the prior art, the drilling of the through hole of the composite material refers to a processing mode that a numerical control machine tool is used, cutting parameters (including spindle rotating speed, feeding speed and feeding distance) are set, and a drilling tool of a certain type is adopted to start processing from the upper surface of the composite material until the drilling tool penetrates through a workpiece from the lower surface of the composite material.

In the first example, the size of the material C-SIC ceramic matrix composite of the composite workpiece is 100mm x 10mm, the numerical control machine tool used is a Daewoo ACE V500 numerical control machine tool, the model of the drilling tool is BOSCH- Φ 6-024, and the set cutting parameters are: the main shaft rotating speed is 3000R/MIN, the feeding speed is 20MM/MIN, and the feeding distance is 15MM (>10MM, so that the workpiece is ensured to be drilled through). The drilling results are shown in fig. 5(a) and 5 (b).

Example two: drilling a composite through hole by using the system and the method of the embodiment;

in the system for drilling the composite material through hole, cutting parameters (including the rotating speed of a main shaft, the feeding speed and the feeding distance) are set by using a numerical control machine tool, a hole is drilled downwards from the upper surface of a workpiece by using a drilling tool of a certain type, and part of the drilling hole depth (for example, 1/2 hole depth) is drilled; and drilling upwards from the lower surface of the workpiece by adopting another drilling tool of the same model, and drilling the residual hole depth to finish the processing of the through hole.

In the second example, the size of the material C-SIC ceramic matrix composite material of the composite material workpiece is 100mm x 10mm, the numerical control machine tool used is a Daewoo ACE V500 numerical control machine tool, the model of the drilling tool is BOSCH- Φ 6-024, and the set cutting parameters are: the main shaft rotating speed is 3000R/MIN, the feeding speed is 20MM/MIN, the feeding distance of the drilling tool (upper part) is 5MM (<10MM, the workpiece is guaranteed not to be drilled through), and the feeding distance of the drilling tool (lower part) is 6MM (>5MM, the workpiece is guaranteed to be drilled through). The drilling results are shown in fig. 6(a) and 6 (b).

The experimental results of the first comparative example and the second experimental example show that compared with the prior art for drilling the composite through hole, the through hole processed by the system for drilling the composite through hole with high quality can obtain better hole outlet processing morphology, and the defects of fiber tearing, layering, peeling, edge breakage and the like at the hole outlet can be effectively avoided.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for high quality drilling of composite through holes, comprising:

the drilling device comprises a first drilling tool and a second drilling tool which are oppositely arranged from top to bottom, wherein the first drilling tool feeds downwards to drill the upper half part of the through hole in the workpiece, and the second drilling tool feeds upwards to drill the lower half part of the through hole in the workpiece.

2. The system for high quality drilling of composite through holes of claim 1, wherein the first and second clamp bodies are disposed in a horizontal plane, opposite and spaced apart from each other.

3. The system for high quality drilling of composite through holes of claim 1 or 2, wherein the first and second clamp bodies are movable.

4. The system for high quality drilling of composite through holes of claim 1, wherein the first and second clamp bodies are each of a C-shaped configuration.

5. The system for high quality drilling of composite through holes of claim 4, wherein the first and second clamp bodies have C-shaped openings facing each other for clamping the workpiece from both sides thereof.

6. The system for high quality drilling of composite through holes of claim 1 wherein the first drilling tool and the second drilling tool are vertically disposed, the first drilling tool being attached to a first main shaft and the second drilling tool being attached to a second main shaft.

7. The system for high quality drilling of composite through holes of claim 1 further comprising a positioning device comprising a positioning tool secured to a side of the workpiece to determine the coordinates of the workpiece.

8. The system of claim 1 further comprising a numerical control device and a chip cleaning device, wherein the numerical control device is coupled to the drilling device, and wherein the chip cleaning device includes a suction device, and wherein the suction device is configured to extend the conduit to a work-piece machining location.

9. Method for producing through holes with a system for high quality drilling of composite through holes according to any of claims 1 to 8, characterized by the following steps:

10. The method as claimed in claim 9, wherein during the drilling process, the coordinates of the hole to be processed of the composite material workpiece are determined by using a numerical control device, drilling parameters are set, and the drilling process is controlled; chips produced by the drilling process are cleaned with a chip cleaning device.