3.2 Hollow Carbide Tips - GB2534370A:
Key Excerpt:
"The cutting elements of the present invention overcome the problems associated with the expense involved in producing and using button bits for a drill, more specifically button bits for a DTH drill. By manufacturing a button bit having a hollow, the amount of material used to produce the button bit is reduced; this significantly reduces costs, while surprisingly still maintaining the overall structure and function of the button bit."