The joint part is the weakest link of the abrasive belt under the action of external force. In the production process, the joint of abrasive belt is the key point of technological work, because it is directly related to the use of abrasive belt. Two indexes are mainly used for the evaluation of joint quality, namely strength and thickness. The joint form determines the structural form of abrasive belt. Here are some structural forms of abrasive belt.
1. Joint-less abrasive belt
Joint-less abrasive belt is made by cylinder cloth as matrix. It needs a series of processes such as raw cloth treatment, gluing, sand planting and curing.
This kind of abrasive belt is an early product. Due to the limitation of cylinder cloth matrix, production equipment and process, it can not meet the requirements of specifications in the current market, especially the wide abrasive belt. The low production efficiency and the complex process caused that it has been eliminated in the modern abrasive belt production and replaced by the abrasive belt with joint.
2. Joint abrasive belt
Abrasive belts with joints are divided into two categories: lap joints and butt joints. In the past, the lap joints are very common in the market, while they have been replaced by butt joints now. More than 75% of abrasive belts are butted in Europe and America.
(1) Lap abrasive belt
Two joints of a abrasive belt are ground into inclined edges coated with joint glue according to the determined width requirements. Then they are overlapped and pressed. Generally, large joint angle is adopted for wide abrasive belt to facilitate joint operation.
(2) Butt abrasive belt
Two joint edges are butted together with the gasket material pressed into the sand surface or cloth base surface. Before joining, grind the front (sand surface) or back (cloth surface or paper surface) of two joint edges. The grinding thickness is equivalent to the thickness of the gasket material to ensure that the joint thickness is equivalent to the rest part. When required by users, the thickness of the joint can be thinner than the rest part (negative allowance).
3. Embedding abrasive belt
The embedding abrasive belt is a form of the butt abrasive belt. They are very similar in form. The difference lies in the different materials and forms of gasket materials. Embedding method is suitable for abrasive belts with extremely thick base materials.
4. Single joint and multiple joint abrasive belt
Single joint abrasive belt: It is suitable for the situation that the width of abrasive belt does not exceed the width of abrasive cloth (paper). The above methods are applicable.
Multiple joint abrasive belt: It is suitable for the situation that the width of abrasive belt exceeds the width of abrasive cloth (paper). Multiple joint abrasive belt is a belt with two or more joints on one abrasive belt.
5. Spiral joint abrasive belt
It has the same function as multiple joint abrasive belt, which is connecting narrow abrasive belts (cloth and paper) into abrasive belts several times wider. This kind of abrasive belt is with high strength, small elongation and good grinding performance because of its double-layer structure.