What should be paid attention to when processing blister fiberboard with special cutting equipment for knife die?

Matters needing attention in processing blister fiberboard with special cutting (carving) equipment for knife die

> Plastic-absorbing fiberboard (high-density fiberboard, used for plastic-absorbing die pad and sandwich die substrate) Features: dense fiber, large dust, easy to heat and burn, easy to delaminate and collapse; The requirements for plane adsorption, tool selection, layered cutting, depth control and dust removal are high, and the processing quality directly determines the problems of burr and flash of subsequent punching and plastic absorption products.

I. Key points of plate incoming materials and clamping and fixing

1. Water content control of plate

The moisture content of fiberboard is suggested to be controlled at 69%; If the moisture content is too high, it is easy to bubble and delaminate when processing is heated; When the moisture content is too low, the plate becomes brittle, and the corners and holes are easy to collapse. Plates should be laid flat when entering the site to avoid being affected with damp and warping.

2. Flatness inspection

Make sure that the warpage of the plate is ≤0.2mm/m before processing. The large warpage directly leads to the inconsistency of Z-axis depth, the half-cutting is not thorough, the whole cutting is continuous, and the thickness accuracy of the die pad is invalid.

3. Vacuum adsorption fixation

-Partition vacuum adsorption table must be used and sealed well; When the local plate is breathable, it can be sealed with the backing film to prevent the plate from shaking and shifting during the cutting process, which will cause knife lines, edge collapse and size drift.

It is forbidden to process the plate locally suspended, and the cutting vibration in the suspended position will tear the fiber of the plate.

4. Plate spacer: The table top is paved with a thin backing plate to avoid damaging the equipment table top during cutting.

Second, the tool selection and clamping

1. Tool type

Tungsten steel three-edge straight cutter/spiral milling cutter with chip breaking groove is preferred, which has good chip removal, smooth upper and lower cuts and reduces fiber pulling and edge collapse; Single-edged knives are not recommended, which are prone to chip sticking and high fever.

-Conventional contour cutting: φ 46 mm three-edge cutting knife; Small diameter cemented carbide milling cutter is selected for small inner hole and narrow groove.

-The tool must be sharp, and the blunt tool will rub and heat up, resulting in burning, blackening and burr, which will greatly shorten the service life of the tool.

2. Clamping specifications

-Clean the chuck and the handle, with the handle extending into the chuck ≥18mm, and the tool suspension should be as short as possible to reduce jitter; Chuck wear should be replaced in time to prevent the eccentric vibration of the cutter and ripple knife marks.

-After tool change, try to cut, and check the size and incision quality.

Three, processing parameters and cutting technology (core, burning plate, layered)

1. Cut in layers, and it is forbidden to cut deeply.

The thickness of fiberboard is 3‑18mm, it is forbidden to cut the full depth of Z axis at one time, and it must be cut in layers; The thick plate is cut in 24 layers, which reduces the cutting load of single tool, is beneficial to chip removal, and reduces the friction and heat burning and plate cracking.

> plastic-absorbing die often has half-cutting (line pressing) and full-cutting, and the Z-axis depth accuracy requirement is ≤ 0.02 mm; Check the tool alignment before machining to prevent the depth from being too cut or not cut through.

2. Speed feed matching

Spindle with high rotation speed and reasonable feed, avoiding slow feed at low speed (long friction time, easy burning and blackening); Turn on corner deceleration at corner position to prevent corner edge collapse.

3. Give priority to downstream milling to reduce fiber tearing and make the incision smoother; Reverse milling is easy to pull the fiber, resulting in fuzzing and delamination.

4. Treatment of small holes and narrow grooves: pre-drilling and reaming are preferred for small holes to reduce edge collapse caused by cutter extrusion; Slight R compensation is added to the drawings at sharp corners to reduce the probability of edge collapse.

Four, dust removal and heat dissipation (fiberboard processing high frequency fault point)

1. The dust removal system must be fully opened: processing will produce a lot of fine fiber dust; The dust outlet is aimed at the cutting position, and the sawdust is taken away in time. The accumulation of sawdust will accumulate heat and burn the board, and at the same time wear the tool.

2. The air cooling system of the main shaft of the equipment remains normal; Cutting fluid is generally not used to process fiberboard, and wet method will cause the board to absorb water, expand and delaminate.

3. Regularly clean the fiber dust in the table top and adsorption holes, so as to avoid blocking the adsorption holes, resulting in weak adsorption of plates.

Five, equipment operation and special requirements of knife die process

1. Accuracy check

The plastic suction die is very sensitive to the size, and the X/Y repeated positioning accuracy (within ±0.01mm) should be checked before processing. After machining the first piece, it is necessary to re-measure the contour and depth with calipers. The dimensional deviation will directly lead to the overflow and material shortage of subsequent punching products.

2. Bridge location, slotting and avoidance processing

The bridge position of the sandwich knife die and the groove of the knife bar should be vertical, and the slope should not be too large; The gap between the groove width and the cutter bar is controlled reasonably. If the gap is too large, the cutter bar shakes, and if it is too small, it is difficult to install the cutter.

3. Corner, dense cavity: dense small holes and sharp corners, reducing the amount of cutting with a single knife and preventing edge collapse and corner loss.

Six, post-processing and quality inspection

1. After the processing is completed, use an air gun to clean the residual fiber debris in the gap of the plate; Check the incision for delamination, black burn marks and edge collapse; Slight burr can be lightly repaired with fine sandpaper, and seriously burned and layered, it will be scrapped directly.

2. After the fiberboard is processed, avoid being piled up in the open air to get wet. After being wet, the thickness of the board will expand, and the assembly accuracy of the die will be invalid.

VII. Safety and Daily Maintenance

1. Operators wear dust masks and goggles, and fiber dust is irritating to respiratory tract.

2. Regularly clean the fiber dust of the lead screw, guide rail and limit switch. The dust entering the guide rail will accelerate the wear and affect the equipment accuracy.

3. Check the tool for wear regularly. Once the incision appears burr and blackening, repair or replace the tool in time.