Pencil board processing:
The logs are split, cut and sawed into wood blocks, and then cut into pencil boards with a cutting machine after hydrothermal treatment. The plate is 184mm long, 73mm wide and 4.8 ~ 5.2 mm thick. After heating (60 ~ 120℃) and drying at high temperature (130 ~ 200℃), the pencil board becomes soft and easy to roll.
2. lead core processing graphite lead cores are prepared from graphite and clay according to a certain proportion, mixed by a kneader and a three-roller machine, extruded by a core press with a certain size (for example, the lead core diameter of HB ~ 3h is 1.80 ~ 2. 10 mm), dried and heated to dry (50 ~ 150℃). The processing of colored lead core is similar to that of graphite lead core, but it does not need sintering.
3. There are two processing methods of lead core: one is to mix clay, talcum powder, adhesive, pigment, grease and wax evenly, and then make it through molding and drying, which is called mixing method; The other is to mix porcelain clay, talcum powder, pigment and adhesive evenly and then squeeze them into lead core, or put the dried lead core into an oil core container to make it fully absorb oil at a certain temperature, which is called oil immersion method.
4. Processing of the pencil rod: the pencil board is planed into a groove board with a thickness of 4. 1 ~ 4.2 mm and a core groove corresponding to the diameter of the lead core, then the lead core and the pencil board are bonded together with an adhesive, heated (50 ~ 120℃) and dried 1 ~ 8 hours in a clamping state, and then processed into a certain length by a planer.
5. Appearance decoration: paint and print white pencils, cut lights, print trademarks, install glue heads, caps, etc. Make it a finished pencil with certain specifications, appearance color and pattern.
Extended data:
1. Is pencil lead poisonous?
Actually, pencil lead is not poisonous. Lead is toxic. The main raw materials for making pencil lead are graphite and clay, so pencil lead is nontoxic.
The main components of pencil refill are graphite and clay. Graphite is a scaly solid with metallic luster, in which there are carbon-carbon chemical bonds and van der Waals force is between layers. Carbon-carbon chemical bonds are very stable, so they are difficult to break. This is why diamonds and graphite are made of carbon, but their physical properties and prices are quite different. Nothing in the human body can break the carbon-carbon chemical bond, so it is certain that pencil lead is safe (unless it is inside).
2. Is the pencil rod toxic to metals?
The appearance of the pencil rod can be covered with mold or pencil paint, which can protect the pen holder on the one hand and improve the appearance on the other, but the pigment will contain trace heavy metals, and a small amount of contact will not affect it, but it is still inappropriate to bite the pen holder into your mouth.
References:
Pencil-Baidu Encyclopedia