Forward and reverse clamping and positioning method for weak-rigidity honeycomb part

Abstract

The invention belongs to a numerical control machining technology, and relates to a positive and negative clamping and positioning method for a weakly rigid honeycomb part. Comprising the steps that 1, the outer diameter of the rigid lining is determined; and 2, two rigid linings are adopted to assist in positioning the honeycomb part blank for machining, and the honeycomb part is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to numerical control machining technology and relates to a positive and reverse clamping positioning method for a weak-rigidity honeycomb part. BACKGROUND

[0002] In the field of aerospace, lightweight, high reliability, long life and low cost are continuously developed, and composite materials are increasingly used in the field of aerospace because of their designability, high specific strength, fatigue resistance, corrosion resistance, easy repair and light specific gravity. The honeycomb core composite material part is widely used in helicopter structures because of its high specific strength and specific stiffness. However, the honeycomb core has poor lateral load-bearing capacity due to the existence of the honeycomb core grid, and is easily elastically deformed under lateral stress. The existing machining positioning method is as follows: two positioning blocks are placed at right angles on the machine tool workbench, and the coordinates of the intersection of the right-angle edges are measured. Then, the honeycomb blank is processed on the bottom surface and is pasted with double-sided adhesive tape, and is pasted on the machine tool workbench after being pasted with the adjacent two right-angle edges and the positioning block placed vertically. At this time, the coordinates of the intersection of the right-angle edges of the positioning block can be used as the machining origin coordinates. However, due to the uncontrollable extrusion deformation of the honeycomb when it is pasted with the positioning block, the positioning origin of the front and back surfaces is misaligned when the honeycomb is machined on both sides, which causes the misalignment of the connecting position and the step of the profile, and affects the quality of the part and increases the probability of part rejection. SUMMARY

[0003] The application aims to provide a positive and reverse clamping positioning method for a weak-rigidity honeycomb part, and improve the part yield.

[0004] The technical scheme of the application is as follows: A positive and reverse clamping positioning method for a weak-rigidity honeycomb part, comprising the following steps: Step 1: determining the outer diameter of a rigid bushing; Step 2: using two rigid bushings to assist in positioning the honeycomb part blank for machining to obtain the honeycomb part.

[0005] Further, step 1 specifically comprises the following steps: A honeycomb blank of the same grade as the part is taken, and two circular holes with the same diameter are inserted on the honeycomb blank at a certain distance apart by using an inserted milling cutter; A nylon rod with a diameter larger than the diameter of the circular hole by a first difference value is turned by a lathe, and the nylon rod is inserted into the circular hole. If the connection between the nylon rod and the circular hole is extremely loose, the diameter of the nylon rod is increased by the first difference value and inserted into the circular hole to determine the connection tightness between the nylon rod and the circular hole; When the connection tightness between the nylon rod and the circular hole is in a moderate state of static state without falling off, the diameter of the nylon rod is increased by a second difference value and inserted into the circular hole to determine the connection tightness between the nylon rod and the circular hole; When the connection between the nylon rod and the round hole is in the cracking state, the diameter of the nylon rod is recorded and rounded down to obtain the outer diameter of the rigid bushing that can be stably fixed in the round hole of the honeycomb, wherein the first difference is greater than the second difference.

[0006] Further, the length of the bushing is less than the thickness of the honeycomb by 2mm.

[0007] Further, step 2 specifically includes: Step 21: Widening the area on one side of the original honeycomb part blank as the rigid bushing installation area, using a plunge milling cutter to plunge out two round holes at a certain distance on the area; Step 22: Place the honeycomb on the flat plate tooling and then on the machine tool platform, and insert the two rigid bushings into the two round holes; Step 23: Use the machine tool to set the position, use the rigid bushing to assist in determining the machining program coordinate system, and then fine-tune the position of the flat plate tooling to straighten the hole center of the other bushing along the X-axis direction of the machine tool, so that the X-axis direction of the machining program coordinate system is consistent with the X-axis direction of the machine tool coordinate system; In this state, the front surface of the honeycomb part is machined; Step 24: Turn over the honeycomb, set the machining program coordinate system again, fine-tune the position of the flat plate tooling, straighten the hole center of the other bushing along the X-axis direction of the machine tool, so that the X-axis direction of the machining program coordinate system is consistent with the X-axis direction of the machine tool coordinate system; In this state, the back surface of the honeycomb part is machined.

[0008] Further, in step 21, the width of the widened area is 80mm.

[0009] Further, in step 23, the X and Y planes of the machining program coordinate system are the honeycomb planes, and the Z axis of the machining program coordinate system is upward along the shaft of one of the bushings.

[0010] Further, in step 24, the X and Y planes of the machining program coordinate system are the honeycomb planes, and the Z axis of the machining program coordinate system is upward along the shaft of one of the bushings as described in step 23.

[0011] Further, in step 1, the inner diameter of the rigid bushing is Φ10mm.

[0012] Further, the first difference is 3mm.

[0013] Further, the second difference is 1mm.

[0014] The beneficial effects of the present application are: The present application directly realizes the honeycomb machining origin positioning by adding a rigid bushing, instead of indirectly realizing the machining origin positioning by abutting against the vertical surface of the positioning block. On the one hand, the additional installation error in indirect positioning is avoided, and on the other hand, the uncontrollable deformation caused by lateral extrusion when abutting is avoided. The clamping and positioning accuracy of the weak rigid honeycomb part is significantly improved, and the surface quality of the position of the type surface connection during the front and back surface machining of the weak rigid honeycomb part is improved. DETAILED DESCRIPTION

[0015] The present application aims to solve the uncontrollable problem of repeated positioning and clamping error of weak rigid parts, and proposes a front and back clamping and positioning method for weak rigid honeycomb parts. The method provides a positioning reference by adding a rigid bushing to improve the clamping and alignment error. The method comprises the following operations: Operation 1: Determine the size (outer diameter and inner diameter) of the rigid bushing First, take a honeycomb blank of the same grade as the part (the length and width dimensions can refer to 160mm*120mm), and use a Φ19.05mm slotting cutter to insert two circular holes with a diameter of 19.05mm at a certain distance on the honeycomb.

[0016] Further: Use a lathe to turn a nylon rod (the material of the nylon rod can refer to PA1010). First, process a nylon rod with a length of less than 2mm and a diameter of Φ20mm. Since the honeycomb lattice has good elasticity, the Φ20mm nylon rod can be almost inserted (very loose) into the Φ19.05mm hole.

[0017] Further: Gradually increase the diameter of the nylon rod. As the diameter of the nylon rod increases, the friction force gradually increases after being inserted into the honeycomb opening, until it can be stably fixed in the hole (tight) even with shaking. When the diameter of the nylon rod is further increased, the honeycomb is cracked.

[0018] Further: Take the diameter of the bushing that cracks the honeycomb circular hole down to obtain the outer diameter size of the rigid bushing that can be stably fixed in the honeycomb Φ19.05mm circular hole.

[0019] Further: Drill a through hole (such as Φ10mm) in the center of the bushing as a positioning hole.

[0020] Operation 2: Front and back surface machining of the honeycomb part Widen one side of the original honeycomb part blank by 80mm as a rigid bushing installation area, and use a Φ19.05mm slotting cutter to insert two circular holes with a diameter of 19.05mm at a certain distance on the area.

[0021] Further: Use a lathe to turn out two rigid bushings with the size determined in step 1.

[0022] Further: after placing the honeycomb on the flat plate tooling on the machine tool platform, slowly insert two rigid bushings into the two 19.05mm diameter round holes to avoid tearing the honeycomb due to excessive amplitude.

[0023] Further: use the machine tool dial positioning to determine the machining program coordinate system, wherein the X, Y plane of the machining program coordinate system is the honeycomb plane, and the Z axis of the machining program coordinate system is upward along the spindle of one bushing; Further: fine-tune the position of the flat plate tooling, straighten the hole center of the other bushing along the X axis direction of the machine tool, so that the X axis direction of the machining program coordinate system is consistent with the X axis direction of the machine tool coordinate system.

[0024] Further: perform front surface machining of the honeycomb part in this state.

[0025] Further: turn over the honeycomb, dial the machining program coordinate system again, wherein the X, Y plane of the machining program coordinate system is the honeycomb plane, and the Z axis of the machining program coordinate system is upward along the spindle of the one bushing; fine-tune the position of the flat plate tooling, straighten the hole center of the other bushing along the X axis direction of the machine tool, so that the X axis direction of the machining program coordinate system is consistent with the X axis direction of the machine tool coordinate system.

[0026] Further: perform back surface machining of the honeycomb part in this state.

[0027] Embodiment: In order to facilitate understanding of the present application, the following will briefly describe the present application with examples, but the protection scope of the present application is not limited to the following specific embodiments.

[0028] The example of the present application discloses a weak rigid honeycomb part positioning method. The length of the honeycomb part is 160mm, the width is 120mm, the material grade is NH(YT)-1-2.75-32-δ40, and the following operations are included: Operation 1: Determine the size of the rigid bushing First, take a honeycomb blank with a length and width of 160mm*120mm and a grade of NH(YT)-1-2.75-32-δ40, use a Φ19.05mm plug milling cutter to insert two 19.05mm diameter round holes on the honeycomb at a distance of 50mm.

[0029] Further: use a lathe to turn a PA1010 nylon rod, process a nylon rod with a length of 38mm and a diameter of Φ20mm. Since the honeycomb lattice has good elasticity, the Φ20mm nylon rod can be almost inserted into the Φ19.05mm hole without resistance.

[0030] Further: increase the diameter of the nylon rod gradually (see Table 1), as the diameter of the nylon rod increases, the friction gradually increases after inserting the honeycomb opening, when the diameter of the nylon rod increases to Φ31mm, shake hard can also be stable fixed in the hole. When the diameter of the nylon rod is further increased to Φ33mm, the honeycomb is stretched.

[0031]

[0032] Further: in order to get the appropriate diameter of the nylon rod, the test starts from Φ31mm diameter which can be stable and fixed by shaking hard, and increases by 0.1mm each time. When the diameter of the nylon rod is Φ31.8mm, the honeycomb is stretched.

[0033] Further: from the diameter of the stretched honeycomb round hole bushing, the outer diameter size of the rigid bushing which can be stable and fixed in the honeycomb Φ19.05mm round hole is Φ31mm.

[0034] Further: a Φ10mm through hole is drilled in the center of the bushing as a positioning hole.

[0035] Step 2: processing of the front and back of the honeycomb part The equipment includes Siemens system equipped with 4 tool positions of tool magazine, ultrasonic function of five-axis numerical control ultrasonic machine tool, and the tool includes triangular knife (T2, L40); Take a piece of honeycomb blank with size of 160mm*120mm and brand of NH (YT)-1-2.75-32-δ40, use Φ19.05mm plug milling cutter to plug out two places with diameter of 19.05mm on the honeycomb at a distance of 50mm.

[0036] Further: use lathe to turn out two rigid bushings with diameter of Φ31mm, length of 38mm and inner diameter of Φ10mm determined by step 1.

[0037] Further: place the honeycomb on the flat plate tooling and then on the machine tool platform, slowly insert the two rigid bushings into the two places with diameter of 19.05mm, avoid tearing the honeycomb due to too large action amplitude.

[0038] Further: use the machine tool to measure the center of one of the bushings as the processing origin X, Y coordinates, and the height of the honeycomb surface as the Z coordinate, and then fine-tune the position of the flat plate tooling to straighten the center of the other bushing along the X axis direction of the machine tool.

[0039] Further: use triangular knife to cut a straight line on the honeycomb at a distance of 50mm from the line connecting the centers of the two bushings along the X axis direction of the machine tool, with a cutting depth of 21mm.

[0040] Further: Turn over the honeycomb, and position the same bushing hole center as the machining origin X, Y coordinate again, and take the honeycomb surface height as the Z coordinate, and then fine-tune the position of the flat plate tooling, and straighten the hole center of the other bushing along the machine tool X axis direction.

[0041] Further: Use the triangular knife to cut a straight line on the honeycomb at a position 50 mm away from the connecting line of the two bushing hole centers along the machine tool X axis direction again, and the cutting depth is 21 mm.

[0042] A smooth and flat connecting surface is obtained.

[0043] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements that can be easily thought of by those skilled in the art within the technical range disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for positive and negative clamping and positioning of weak rigidity honeycomb parts, characterized in that: include: Step 1: Determine the outer diameter of the rigid bushing; Step 2: Use two rigid bushings to assist in positioning the honeycomb part blank for processing to obtain the honeycomb part.

2. The method according to claim 1, characterized in that Step 1 specifically includes: Take a honeycomb blank of the same brand as the part, and use a plunge milling cutter to insert two circular holes of the same diameter at a certain distance on the honeycomb blank; A nylon rod is turned on a lathe, the diameter of which is larger than the diameter of the circular hole by a first difference, and the nylon rod is inserted into the circular hole. If the connection between the nylon rod and the circular hole is very loose, the diameter of the nylon rod is increased by the first difference and the rod is inserted into the circular hole to determine the tightness of the connection between the nylon rod and the circular hole; When the tightness of the connection between the nylon rod and the circular hole is in a moderate state where the rod does not fall off in a static state, the diameter of the nylon rod is increased by the second difference value and the rod is inserted into the circular hole to determine the tightness of the connection between the nylon rod and the circular hole; When the tightness of the connection between the nylon rod and the circular hole is in a torn state, the diameter of the nylon rod at this time is recorded and rounded down to obtain the outer diameter of the rigid bushing that can be stably fixed in the circular hole of the honeycomb, wherein the first difference is greater than the second difference.

3. The method according to claim 2, characterized in that The length of the liner is less than 2mm of the honeycomb thickness.

4. The method according to claim 3, characterized in that Step 2 specifically includes: Step 21: Widen one side of the original honeycomb part blank to serve as the rigid bushing installation area, and use a plunge milling cutter to insert two circular holes at a certain distance in this area; Step 22: Place the honeycomb on the flat tooling and then on the machine platform. Insert the two rigid bushings into the two round holes. Step 23: Use the machine tool to position the table and the rigid bushing to determine the machining program coordinate system. Then fine-tune the position of the flat tooling and straighten the hole center of the other bushing along the X-axis direction of the machine tool so that the X-axis direction of the machining program coordinate system is consistent with the X-axis direction of the machine tool coordinate system. In this state, perform front processing of the honeycomb part. Step 24: Turn the honeycomb over, re-position the machining program coordinate system, and then fine-tune the position of the flat tooling. Straighten the hole center of the other bushing along the X-axis direction of the machine tool so that the X-axis direction of the machining program coordinate system is consistent with the X-axis direction of the machine tool coordinate system. Process the reverse side of the honeycomb part in this state.

5. The method according to claim 4, characterized in that In step 21, the widened width is 80 mm.

6. The method according to claim 5, characterized in that In step 23 , the X and Y planes of the machining program coordinate system are honeycomb planes, and the Z axis of the machining program coordinate system is upward along the core axis of a bushing.

7. The method according to claim 6, characterized in that In step 24 , the X and Y planes of the machining program coordinate system are honeycomb planes, and the Z axis of the machining program coordinate system is upward along the core axis of a bushing described in step 23 .

8. The method according to claim 7, characterized in that Step 1 also includes determining that the inner diameter of the rigid bushing is Φ10 mm.

9. The method according to claim 8, characterized in that The first difference is 3 mm.

10. The method according to claim 9, characterized in that The second difference is 1 mm.

Images