Patent Application
20170225280
The present invention relates to a method for producing woodworking spade bits and, more particularly, to a method for producing woodworking tool spade bits to reduce the inventory.
Wood materials generally have special grains, and woodworking spade bits are generally used to proceed with hole drilling operation of the wood materials. With reference to
The diameter of the hole formed by the spade bit 1′ is equal to a width W′ of the main cutting portion 121′. When it is desired to drill holes of different diameters in the wood, a corresponding number of spade bits 1′ of different diameters is required. In manufacture, a plurality of cylindrical rods is subjected to forging and lathing to provide spade bits 1′ having bit portions 121′ with different widths, leading to an increase in the manufacturing costs and inconvenience to inventory.
Furthermore, the shank 1′ and the bit portion 12′ of the spade bit 1′ are made of the same material. The spade bit 1′ is often produced from a low hardness material (such as middle/low carbon steel) to reduce the costs, resulting in a low hardness at the bit portion 12′ which tends to wear after a period of time of use and requires replacement of the whole spade bit 1′. If the whole spade bit 1′ is made from a high hardness material (such as high carbon steel), the costs will be increased significantly, failing to fulfill the economic interest.
U.S. Patent Publication No. 20090269155 discloses a wood flat drill bit and a connecting assembly which are detachably coupled. However, relative axial displacement or loosening is apt to exist between the drill bit and a connecting rod of the connecting assembly after assembly, leading to unstable drilling operation and a large error in the diameter.
An objective of the present invention is to provide a method for producing woodworking tool spade bits to reduce the inventory.
Another objective of the present invention is to provide a method for producing woodworking tool spade bits to prolong the service life of the woodworking spade bits.
A method for producing woodworking spade bits according to the present invention includes:
producing a plurality of shanks from a plurality of cylindrical rods, with each of the plurality of shanks having a first longitudinal axis and including a front end having a front connecting portion, with the first connecting portion including two front inclined sides extending forwards and away from the first longitudinal axis, with the two front inclined sides having a first angle therebetween, with the front connecting portion further including a front welding face extending between front ends of the two front inclined sides, extending perpendicularly to the first longitudinal axis, and having a first width perpendicular to the first longitudinal axis, with each of the plurality of shanks further including a rear end adapted for coupling with an external tool;
producing a plurality of bits from at least one flat board, with each of the plurality of bits having a second longitudinal axis and including a front end having a drilling portion with a second width perpendicular to the second longitudinal axis and larger than the first width, with each of the plurality of bits further including a rear end having a rear connecting portion, with the rear connecting portion including two rear inclined sides extending rearwards towards the second longitudinal axis, with an angle between the two rear inclined sides being equal to the first angle, with the rear connecting portion further including a rear welding face extending between rear ends of the two rear inclined sides, extending perpendicularly to the second longitudinal axis, and having a width perpendicular to the second longitudinal axis and equal to the first width;
welding the front welding face of each of the plurality of shanks and the rear welding face of one of the plurality of bits together, forming a plurality of semi-products of woodworking spade bits;
heat processing and surface treating the plurality of semi-products of woodworking spade bits; and
grinding the plurality of semi-products of woodworking spade bits to obtain a plurality of products of woodworking spade bits.
Each of the plurality of cylindrical rods can be forged and lathed to form one of the plurality of shanks having a first diameter. A rear end of each of the plurality of shanks is a polygon adapted for coupling with the external tool. A front end of each of the plurality of shanks includes a conical portion having increasing diameters away from the rear end and a cylindrical portion in front of the conical portion and having a diameter larger than the first diameter. A front end of the conical portion and the cylindrical portion of each of the plurality of shanks are pressed flat to expand forwards and then subjected to lathing or grinding to form the front connecting portion.
In an example, the at least one flat board includes a flat board having a strength greater than a strength of each of the plurality of cylindrical rods. The flat board is pressed to form the drilling portion and the rear connecting portion and is then subjected to grinding and lathing to make the rear welding face correspond to the front welding face.
In an example, heat processing and surface treating the plurality of semi-products of woodworking spade bits includes a heat treatment for increasing hardness and toughness. The heat treatment includes annealing after welding the front welding face of each of the plurality of shanks and the rear welding face of one of the plurality of bits together. Surfaces of the plurality of shanks and the plurality of bits are further processed by finer surface treatment including sandblasting or vibrational grinding.
In an example, each of the plurality of semi-products of woodworking spade bits is grinded to form two cutting edges on two sides of the drilling portion and to form a pointed guiding portion on a front end of the drilling portion.
The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.
With reference to
With reference to
With reference to
The method further includes a step S4 of heat processing and surface treating the semi-products of woodworking spade bits. In an embodiment, after the front welding face 114 of each shank 1 and the rear welding face 222 of one of the bits 2 are welded together, a heat treatment including anneal is carried out to increase hardness and toughness.
Furthermore, surfaces of the shanks 1 and the bits 2 are processed by finer surface treatment including sandblasting or vibrational grinding.
With reference to
Each shank 1 after step S1 has a fixed shape. The rear coupling portions 22 of the bits 2 after step S2 can have different lengths at the two rear inclined sides 221 (
The bits 2 are made of a material more rigid than the material for the shanks 1 and are, thus, less likely to wear, prolonging the service life. Furthermore, each bit 2 is welded with an associated shank 1 to avoid relative axial displacement during the drilling operation, providing stable operation.
In view of the foregoing, the method according to the present invention increases the production applicability of the woodworking spade bits and reduces the inventory.
Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the scope of the invention. The scope of the invention is limited by the accompanying claims.
