Strengthening and improving process management, comprehensively mastering the production process and ensuring product quality are an important part of the quality management of the plywood manufacturing process. Reasonable improvement of production process can directly affect product quality. While earnestly grasping all the links affecting quality factors, we should pay full attention to the impact of production processes on product quality and ensure the improvement of product quality.
Plywood production is plywood produced from rotary cut veneers. The process includes wood cooking, peeling, sawing, wood centering, wood and veneer cutting, drying, shearing, veneer finishing and grading, gluing, blanking, pre-pressing, hot pressing, sawing Side sanding, classification and other inspection and packaging processes. Each process has strict technical requirements. Whether production according to process requirements has a direct impact on product quality, the following only talk about the rough understanding of the main problems in the production process.
1 rotary cutting
In order not to leave hidden dangers to product quality, it is necessary to strictly control the flow of substandard products into the next process. The veneer cutting requires that the thickness of the veneer is uniform, and the difference between the thickness of the two sides and the middle three points does not exceed ± 0 5 mm, and the surface finish and the tensile strength of the horizontal stripes should meet the requirements. However, due to various factors, the pass rate of each sampling can only reach 70% to 85%. In order to improve product quality, the relevant processes should be rationally adjusted, as shown in Table 1. Through the above reasonable adjustment of the process
Table 1 Causes and improvement methods of common defects in veneer cutting process
Defect name generation cause improvement method
The thickness of the veneer exceeds the error specification (the outer ring is thick and the inner ring is thin)
1 The height of the knife is too high.
2 The back angle is too large, which has a “cut-in†effect on the wood segment.
3 The auxiliary slide is not tilted properly.
4 The main slide wears a saddle shape.
1 Adjust the knife height so that it is between -0 5 and +0 5mm.
2 Observe whether the width of the bright part of the blade and the wood section is between 3 and 4 mm, and the adjusted angle is slightly reduced.
3 Forward-tilt auxiliary slide to reduce the inclination of the auxiliary slide.
4 Repair and restore the machine's main slide level.
The board has a tight edge
1 The pressure rib of the pressure gauge is not straight, or the blade is not straight, which makes the veneer difficult to flatten.
2 The middle press of the pressure gauge is too large, and the wooden section is slightly bent by the force, resulting in a tight edge.
3 The knife is blunt, and the wooden section produces a tight edge due to friction.
4 For soft materials, the long axis is too tight, resulting in a loose outer edge of the outer ring and a tight edge on the inner ring.
5 The board began to level, but then the loose side appeared.
6 The oil knife produces a tight edge.
1 Re-replace the pressure gauge or rotary knife, the grinding should be straight, the knife and the pressure gauge should be installed straight, and the anti-bending roller and the middle edge of the blade should be adjusted to 0 1mm.
2 Slightly reduce the degree of press in the middle of the pressure gauge.
3 Zoom in slightly on the back corner or change the knife.
4 Reduce the card cutter slightly.
5 The pressing rate at both ends of the pressure gauge is too small.
6 Start turning and turn the back corner slightly larger.
Board burr
1 The outer circumference of the wooden section is adhered to sediment, bruises, and the blade has a small breach or a curling edge.
2 The knife is not sharp and the oil knife is not enough.
3 The pressure gauge is not installed correctly and the press is not enough.
4 The wood section is not soft enough.
1 Oil knife, severe tool change.
2 Fine oil knife (timely tool change).
3 Adjust the position of the pressure gauge.
4 Increase the cooking time of the wood section.
Board hair
1 Rotary cut softwood trees are blunt, the edges are not sharp, and the oil knives are not enough.
2 Softwood segments are softened excessively.
1 Rotary cutting sharpness, when the grinding angle of the rotary knife is greater than 20°, the grinding angle is reduced to below 19°3 0′, and the oil knife is fine.
2 Reduce the cooking temperature, reduce the time, cool the wood section, balance the inside and outside, and then rotate. The smoothness of the veneer is poor, and the back crack is large (the veneer is soft)
1 The pressure gauge h0 on the cutting edge is not correct, h0 is high, and it is not over-pressed.
2 The hardwood and extra-hardwood species are not soft enough to be cooked and softened.
3 The knife door is too large and exceeds the thickness of the board.
4 The knife is not sharpened or the oil knife is not enough.
5 The pressure ribs are severely worn and cannot be pressed.
1 Lower h0 to equal 1 / 4 ~ 1 / 3 of the knife door.
2 Extend the cooking time of the wood section so that the wood core reaches 45 °C or above.
3 Adjust the small knife door so that the thickness of the veneer is specified.
4 change the knife, work oil knife.
5 Replace the pressure gauge and the new pressure gauge edge should be rounded.
The ridged knife door on the surface of the veneer is blocked by debris.
Eliminate the improvement of the knife door debris, so that the quality of the unscrewing veneer is greatly improved.
Plywood production is plywood produced from rotary cut veneers. The process includes wood cooking, peeling, sawing, wood centering, wood and veneer cutting, drying, shearing, veneer finishing and grading, gluing, blanking, pre-pressing, hot pressing, sawing Side sanding, classification and other inspection and packaging processes. Each process has strict technical requirements. Whether production according to process requirements has a direct impact on product quality, the following only talk about the rough understanding of the main problems in the production process.
1 rotary cutting
In order not to leave hidden dangers to product quality, it is necessary to strictly control the flow of substandard products into the next process. The veneer cutting requires that the thickness of the veneer is uniform, and the difference between the thickness of the two sides and the middle three points does not exceed ± 0 5 mm, and the surface finish and the tensile strength of the horizontal stripes should meet the requirements. However, due to various factors, the pass rate of each sampling can only reach 70% to 85%. In order to improve product quality, the relevant processes should be rationally adjusted, as shown in Table 1. Through the above reasonable adjustment of the process
Table 1 Causes and improvement methods of common defects in veneer cutting process
Defect name generation cause improvement method
The thickness of the veneer exceeds the error specification (the outer ring is thick and the inner ring is thin)
1 The height of the knife is too high.
2 The back angle is too large, which has a “cut-in†effect on the wood segment.
3 The auxiliary slide is not tilted properly.
4 The main slide wears a saddle shape.
1 Adjust the knife height so that it is between -0 5 and +0 5mm.
2 Observe whether the width of the bright part of the blade and the wood section is between 3 and 4 mm, and the adjusted angle is slightly reduced.
3 Forward-tilt auxiliary slide to reduce the inclination of the auxiliary slide.
4 Repair and restore the machine's main slide level.
The board has a tight edge
1 The pressure rib of the pressure gauge is not straight, or the blade is not straight, which makes the veneer difficult to flatten.
2 The middle press of the pressure gauge is too large, and the wooden section is slightly bent by the force, resulting in a tight edge.
3 The knife is blunt, and the wooden section produces a tight edge due to friction.
4 For soft materials, the long axis is too tight, resulting in a loose outer edge of the outer ring and a tight edge on the inner ring.
5 The board began to level, but then the loose side appeared.
6 The oil knife produces a tight edge.
1 Re-replace the pressure gauge or rotary knife, the grinding should be straight, the knife and the pressure gauge should be installed straight, and the anti-bending roller and the middle edge of the blade should be adjusted to 0 1mm.
2 Slightly reduce the degree of press in the middle of the pressure gauge.
3 Zoom in slightly on the back corner or change the knife.
4 Reduce the card cutter slightly.
5 The pressing rate at both ends of the pressure gauge is too small.
6 Start turning and turn the back corner slightly larger.
Board burr
1 The outer circumference of the wooden section is adhered to sediment, bruises, and the blade has a small breach or a curling edge.
2 The knife is not sharp and the oil knife is not enough.
3 The pressure gauge is not installed correctly and the press is not enough.
4 The wood section is not soft enough.
1 Oil knife, severe tool change.
2 Fine oil knife (timely tool change).
3 Adjust the position of the pressure gauge.
4 Increase the cooking time of the wood section.
Board hair
1 Rotary cut softwood trees are blunt, the edges are not sharp, and the oil knives are not enough.
2 Softwood segments are softened excessively.
1 Rotary cutting sharpness, when the grinding angle of the rotary knife is greater than 20°, the grinding angle is reduced to below 19°3 0′, and the oil knife is fine.
2 Reduce the cooking temperature, reduce the time, cool the wood section, balance the inside and outside, and then rotate. The smoothness of the veneer is poor, and the back crack is large (the veneer is soft)
1 The pressure gauge h0 on the cutting edge is not correct, h0 is high, and it is not over-pressed.
2 The hardwood and extra-hardwood species are not soft enough to be cooked and softened.
3 The knife door is too large and exceeds the thickness of the board.
4 The knife is not sharpened or the oil knife is not enough.
5 The pressure ribs are severely worn and cannot be pressed.
1 Lower h0 to equal 1 / 4 ~ 1 / 3 of the knife door.
2 Extend the cooking time of the wood section so that the wood core reaches 45 °C or above.
3 Adjust the small knife door so that the thickness of the veneer is specified.
4 change the knife, work oil knife.
5 Replace the pressure gauge and the new pressure gauge edge should be rounded.
The ridged knife door on the surface of the veneer is blocked by debris.
Eliminate the improvement of the knife door debris, so that the quality of the unscrewing veneer is greatly improved.
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