Basic theoretical knowledge of woodworking

Basic knowledge theory: woodworking construction technology and standards. The carpentry part depicts the five senses of the house. If the facial features are not correct, there is no beauty. For woodworking construction, we should pay attention to the following points:

1. Materials must be genuine, not shoddy, and be constructed in strict accordance with the budget and drawings.

2. All newly-made brick walls and wooden ornaments made on bathroom walls, such as wardrobes and carved walls, must be painted with moisture-proof paint twice on the surfaces of brick walls and plywood respectively before the next procedure can be carried out.

3. Make wooden ornaments on the original wall, such as door covers, window covers and footstones.

Saw blade basic knowledge release: 2009-11-2216: 21| Author: Ling Xiao | Source: Woodworking Tool Community Portal Carbide saw blade is the most commonly used tool for wood products processing, and the quality of carbide saw blade is closely related to the quality of processed products. Correct and reasonable selection of cemented carbide saw blade is of great significance for improving product quality, shortening processing cycle and reducing processing cost.

Carbide saw blade contains many parameters, such as the type of alloy cutter head, matrix material, diameter, number of teeth, thickness, tooth profile, angle, aperture, etc. These parameters determine the machining ability and cutting performance of the saw blade. When selecting the saw blade, we should correctly select the saw blade according to the type, thickness, sawing speed, sawing direction, feeding speed and sawing width of the sawing material.

(a) Selection of cemented carbide type

Commonly used cemented carbide types are tungsten cobalt (code YG) and tungsten titanium (code YT). Tungsten-cobalt cemented carbide is widely used in wood processing industry because of its good impact resistance. The commonly used model in wood processing is YG8-YG 15, and the number after YG indicates the percentage of cobalt content. With the increase of cobalt content, the impact toughness and bending strength of the alloy increase, but the hardness and wear resistance decrease, so it should be selected according to the actual situation.

(2) Selection of matrix

1.65Mn spring steel has good elasticity and plasticity, economical material, good heat treatment hardenability, low heating temperature and easy deformation, and can be used for cutting saw blades with low requirements.

2. Carbon tool steel has high carbon content and high thermal conductivity, but the hardness and wear resistance drop sharply at 200℃-250℃, and the heat treatment deformation is large, the hardenability is poor, and it is easy to crack when tempered for a long time. Manufacturing economical tool materials, such as T8A, T 10A, T 12A, etc.

3. Compared with carbon tool steel, alloy tool steel has better heat resistance, wear resistance and handling performance, and the heat deformation resistance temperature is 300℃-400℃, which is suitable for manufacturing high-grade alloy circular saw blades.

4. High-speed tool steel has good hardenability, strong hardness and rigidity, low thermal deformation resistance, belongs to ultra-high strength steel, has stable thermoplasticity, and is suitable for manufacturing advanced ultra-thin saw blades.

(3) Selection of diameter

The diameter of the saw blade is related to the sawing equipment used and the thickness of the sawing workpiece. The diameter of saw blade is small, and the cutting speed is relatively low; The diameter of saw blade is large, which has high requirements for saw blade and sawing equipment and high sawing efficiency. Choose the outer diameter of the saw blade according to different circular saw models.

The diameters of standard parts are110mm (4 inches),150mm (6 inches),180mm (7 inches), 200mm (8 inches), 230mm (9 inches) and 250mm (/. 450 mm (18 inch), 500 mm (20 inch), etc. , and the bottom slot saw blade of precision plate saw is mostly designed as 120 mm.

(4) Selection of the number of teeth

Generally speaking, the more teeth, the more cutting edges per unit time, and the better cutting performance. However, if there are more teeth, there will be more cemented carbide and the price of saw blades will be higher. However, if the teeth are too dense, the amount of chips between the teeth will be smaller, which will easily cause the saw blade to heat up. In addition, if there are too many serrations, if the feed is not properly matched, the cutting amount per tooth is very small, which will aggravate the friction between the cutting edge and the workpiece and affect the service life of the cutting edge. Generally, the tooth pitch is 15-25mm, and the reasonable number of teeth should be selected according to the sawing material.

(5) Selection of thickness

Thickness of saw blade Theoretically, we hope that the thinner the saw blade, the better. Sawing seam is actually a kind of consumption. The material of alloy saw blade matrix and the process of manufacturing saw blade determine the thickness of saw blade. If the thickness is too thin, the saw blade will easily shake when working, which will affect the cutting effect. When selecting the thickness of the saw blade, the working stability of the saw blade and the sawing material should be considered. Some special-purpose materials require a specific thickness and should be used according to the equipment requirements, such as slotted saw blades and scribed saw blades.

(6) Selection of tooth profile

Commonly used tooth profiles include left and right teeth (staggered teeth), flat teeth, stepped flat teeth (high and low teeth), inverted trapezoidal teeth (inverted conical teeth), dovetail teeth (hump teeth), and rare industrial-grade three left and one right, left and right flat teeth, etc.

1. The left and right teeth are widely used, with fast cutting speed and relatively simple grinding. Suitable for cutting and crosscutting all kinds of soft and hard solid wood profiles, density boards, multi-layer boards, particleboard and so on. The left and right teeth with anti-rebound protection teeth are dovetail teeth, which are suitable for longitudinal cutting of various plates with tree joints; The left and right tooth saw blades with negative rake angle are usually used for sawing veneers because of their sharp teeth and good sawing quality.

2. The flat tooth saw is rough, the cutting speed is slow, and the grinding is the simplest. Mainly used for sawing ordinary wood, with low cost, mostly used for aluminum saw blades with smaller diameter to reduce adhesion during cutting, or used for grooving saw blades to keep the groove bottom flat.

3. Stepped flat teeth are the combination of trapezoidal teeth and flat teeth, which are complicated to repair and grind, and can reduce the phenomenon of veneer cracking when sawing, and are suitable for sawing all kinds of single and double veneer artificial boards and fire boards. In order to prevent adhesion, the teeth of aluminum saw blades are mostly stepped flat teeth.

4. Inverted trapezoidal teeth are often used in the bottom slot saw blade of the panel saw. When sawing wood-based panels with double veneers, the slot saw adjusts the thickness to complete the slotting of the bottom surface, and then the main saw completes the sawing of the panels to prevent the edge from collapsing.

To sum up, the left and right teeth should be selected for sawing solid wood, particleboard and medium density fiberboard, which can cut off the wood fiber structure sharply and make the incision smooth; In order to keep the groove bottom flat, flat teeth or left and right flat combined teeth are used; Step flat teeth are generally used for sawing veneer and fireproof board. Because of the high cutting rate, the alloy saw blade used for computer cutting saw is relatively large in diameter and thickness, about 350-450mm in diameter and 4.0-4.8mm in thickness, and most of them use trapezoidal flat teeth to reduce edge collapse and saw marks.

(7) Selection of sawtooth angle

The angle parameters of serrated part are complex and professional, and the correct selection of saw blade angle parameters is the key to determine the sawing quality. The most important angle parameters are rake angle, rake angle and wedge angle.

The rake angle mainly affects the force consumed by sawdust. The larger the rake angle, the better the sharpness of sawtooth cutting, the lighter it is to saw and the more labor-saving it is to push. Generally, when the processed material is soft, choose a larger rake angle, otherwise choose a smaller rake angle.

The angle of the sawtooth is the position of the sawtooth when cutting. Sawtooth angle affects cutting performance. The rake angle γ, rake angle α and wedge angle β have the greatest influence on cutting. The rake angle γ is the cutting angle of the sawtooth. The larger the rake angle, the faster the cutting speed. The rake angle is generally between 10 ~ 15℃. The back angle is the included angle between the sawtooth and the machined surface, and its function is to prevent the sawtooth from rubbing against the machined surface. The greater the back angle, the smaller the friction and the smoother the processed products. The back angle of general cemented carbide saw blade is 65438 05℃. The wedge angle is derived from the front angle and the back angle. However, the wedge angle should not be too small, which has a certain effect on maintaining the strength, heat dissipation and durability of the teeth. The sum of rake angle γ, rake angle α and wedge angle β is equal to 90℃.

(8) Selection of aperture

Aperture is a relatively simple parameter, which is mainly selected according to the requirements of equipment. However, in order to maintain the stability of the saw blade, it is better to choose equipment with larger aperture for the saw blade over 250 mm. At present, the diameters of standard parts designed in China are mostly 20MM (120MM and below), 25.4MM (120-230MM) and 30 (above 250 mm). Some imported equipment also has 15.875MM holes. The mechanical aperture of multi-blade saws is complicated, and many of them are equipped with keyways to ensure stability. No matter the size of the aperture, it can be modified by lathe or wire cutting machine. Lathe can turn washer into large aperture, and wire cutting machine can enlarge the aperture to meet the requirements of equipment.

A series of parameters, such as the type of alloy bit, material of matrix, diameter, number of teeth, thickness, tooth profile, angle and aperture, are combined into a whole cemented carbide saw blade. Only by reasonable choice of collocation can we give full play to its advantages.

Second, the correct use of alloy saw blade back to the directory

(1) Basic requirements:

1. Select the appropriate saw blade according to the design requirements of the equipment.

2. The equipment should have safety protection devices, such as protective cover, power-off braking and overload protection.

3. Have professional operators to install and use, and wear work clothes, protective glasses, earmuffs, etc.

4. The operator can't wear gloves, long hair should be placed in the working cap, and pay attention to the tie and cuffs to prevent danger.

5. Stay away from fire sources and humid environment.

(2) Installation requirements:

1, the equipment is in good condition, the spindle is free from deformation and radial runout, the installation and fixation are firm, and there is no vibration.

2. Check whether the saw blade is damaged, whether the tooth profile is complete, whether the saw plate is smooth and bright, and whether there are other abnormal phenomena to ensure safe use.

3. When assembling, ensure that the arrow direction of the saw blade is consistent with the rotating direction of the main shaft of the equipment.

4. When installing the saw blade, keep the shaft, chuck and flange clean, and the inner diameter of the flange is consistent with the inner diameter of the saw blade, so as to ensure that the flange is closely combined with the saw blade, install the locating pin and tighten the nut. The size of the flange should be appropriate, and the outer diameter should not be less than 1/3 of the saw blade diameter.

5. Before starting the equipment, under the condition of ensuring safety, operate the equipment by one person, inching and idling, and check whether the equipment rotates correctly and whether there is vibration. After the saw blade is installed, it idles for a few minutes without slipping, swinging and jumping, and it works normally.

(3) Use requirements:

1. When working, the workpiece should be fixed and the profile should be positioned in the cutting direction to avoid abnormal cutting. Don't apply lateral pressure or curve cutting, and the feed should be stable, so as to avoid the impact contact between the saw blade and the workpiece, causing the saw blade to be damaged or the workpiece to fly out, resulting in an accident.

2. When abnormal sound and vibration, rough cutting surface or peculiar smell are found in the work, the operation must be stopped immediately, checked in time, and troubleshooting should be carried out to avoid accidents.

3. When starting cutting and stopping cutting, the feed speed should not be too fast to avoid broken teeth.

4. If cutting aluminum alloy or other metals, use special cooling lubricant to prevent the saw blade from overheating, causing damage to toothpaste and affecting the cutting quality.

5. Ensure that the equipment chip removal tank and slag suction device are unblocked, and prevent slag from piling up into blocks, which will affect production and safety.

6, dry cutting, please do not cut continuously for a long time, so as not to affect the service life and cutting effect of the saw blade; When cutting wet film, water should be added for cutting to avoid leakage.

(4) saw blade maintenance:

1. If the saw blade is not used immediately, it should be laid flat or hung by the inner hole. Other articles or feet shall not be stacked on the flat saw blade, and attention shall be paid to moistureproof and anticorrosion.

2. When the saw blade is no longer sharp and the cutting surface is rough, it must be reground in time. Polishing can't change the original angle and destroy the dynamic balance.

3. The internal diameter correction and positioning hole processing of the saw blade must be carried out by the manufacturer. If it is not handled properly, it will affect the use effect of the product and may be dangerous. In principle, reaming should not exceed the original aperture by 20mm, so as not to affect the stress balance.

4. Selection of alloy grinding wheel.

1) resin bonded diamond grinding wheel has weak bonding strength, so it has good self-sharpening, high grinding efficiency, low grinding force and low grinding temperature. Its disadvantages are poor wear resistance and large abrasive loss, and it is not suitable for heavy load grinding.

2) Ceramic bonded diamond grinding wheel is superior to resin bonded diamond grinding wheel in wear resistance and bonding ability, and has the advantages of sharp cutting, high grinding efficiency, small thermal expansion, easy control of precision, rough grinding surface and high cost.

3) Metal bonded diamond grinding wheel has high bonding strength, good wear resistance, small wear, long service life and low grinding cost, and can bear a large load, but its sharpness is poor and it is easy to jam.

4) Abrasive particle size has certain influence on grinding wheel blockage and cutting ability. Compared with fine sand particles, the cutting edge wear of coarse sand particles increases with the increase of penetration depth, and the grinding wheel is easy to block.

5) The hardness of grinding wheel has a great influence on the blockage. High hardness grinding wheel has high thermal conductivity, which is not conducive to surface heat dissipation, but is beneficial to improve machining accuracy and durability.

6) The choice of grinding wheel concentration is an important characteristic, which has a great influence on grinding efficiency and machining cost. If the concentration is too low, the efficiency will be affected. On the contrary, abrasive particles will fall off easily, but the best concentration range of binder is also the best.