Importance of the hottest bit edge band

  • Detail

The importance of bit edge band

the edge band is not the most critical part of the bit, but it is an important factor affecting the drilling process. Any senior tool expert will tell you that there are no unimportant geometric characteristics, and each characteristic will affect the performance of the drill bit. Generally, people do not pay much attention to the geometric characteristics of the edge band on the cylindrical surface of the drill bit, and mistakenly believe that the edge band has little impact on the drilling quality. In fact, each geometric characteristic of the drill bit will affect the success or failure of drilling. The blade band is at the outermost part of the drill bit, forming the outer diameter of the drill bit (see Figure 1) and always in contact with the machined surface of the hole. Due to the existence of the blade belt, the gap is formed, which helps to control the friction and the heat generated by the friction. In addition, the gap can also make the coolant flow into the bit edge, further reducing the heat generation. The blade belt also makes China the largest country in the world in terms of plastic consumption, output and export of plastic products and production and sales of plastic machinery, which is conducive to drilling stability, increasing the strength of drill bits and preventing drill bit adhesion. In addition to these main functions, the size, surface finish and number of cutting edges also affect the quality of drilling and processing time

Fig. 1 the edge band forms the outside diameter of the drill bit. The gap generated by the blade belt can make the coolant flow into the bit edge

the influence of the blade belt size on the hole processing quality

1) when the blade belt height is different, a large jump will be formed, resulting in a large size of the processed hole

2) if the edge band is too wide, the resulting large friction will also lead to the large size of the machined hole; If the edge band is too narrow, the drill bit will be unstable and easy to swing during machining

both of the above conditions will reduce the service life of the drill bit. If the width difference of the blade belt is too large, the radial force is unbalanced during drilling. At this time, due to the inherent "inertia" of the tool, the drilling will be carried out in the direction of low resistance, that is, the radial force is small and the blade belt is narrow

3) the change of the geometric dimension of the blade belt will also affect the drilling. If the taper of the edge band is too large or the width of the edge band from the drill tip to the handle changes too much, the pressure and contact area in drilling will change, so that the cutting force and friction force on the drill bit are uneven, resulting in unstable drilling and machining holes into flares or ellipses

the influence of the surface quality of the blade belt on the hole processing quality

if the blade belt of the drill bit has not been well ground and forms a cylindrical blade belt, the user should repair the blade belt, otherwise, the hole wall will be scratched, pulled or scratched during drilling, resulting in poor surface finish

the number of cutting edges affects the machining quality of holes

the number of cutting edges affects the surface finish, straightness and roundness of machined holes. The more spiral grooves and blade belts, the more contact points, the more stable the hole processing. The common double groove drill has two symmetrically distributed contact points or support points. The tool of this structure is unstable and easy to swing during machining (see Figure 2). It is proved by profilometer that the surface finish is improved rapidly by adding a contact point or bearing surface

Fig. 2 the two contact points of the common double groove drill are symmetrically distributed, which is easy to swing during processing.

the three groove drill forms an odd number of edge bands and contact points, and the drill with three edge bands has a particularly strong anti swing ability. (see Figure 3)

Figure 3 three groove drill bit reduces the swing of the drill bit in the machining hole figure 4 four edge belt drill bit has four contact points

"g" drill bit may be the best choice. This is a double groove four edge band bit, also known as DB bit (crowding bit). Guide edge of "g" type drill 3) control function of ring stiffness testing machine: behind the belt are two strip of extruding edge, which are used to extrude the hole wall surface (since the manufacturing of this kind of drill requires high technology, the manufacturer should be carefully selected). The contact point of the four edge belt drill is twice as much as that of the ordinary double groove two edge belt drill. The extra two contact points can make the drilling more stable. This form is like putting the reconstruction BYD supply chain into a square axis in a round hole. The square contact point can also make the drill evenly stressed, as shown in Figure 4

Fig. 5 the universal tensile testing machine for machining holes with DB drill adopts microcomputer closed-loop control. The diameter accuracy reaches 0.013mm, and the roughness reaches 32rms

many users cancel the reaming process after using DB drill, reducing the processing time. Some users are not satisfied that machining a hole requires so many processes: drilling a central hole → drilling with an ordinary double slot drill → reaming. His first thought was to optimize the geometry of the drill point, but he failed to achieve a satisfactory surface finish. Then, the special tool drilling reaming compound tool is considered for machining. Finally, the expert suggested him to use DB drill bit. After tests, the two extruding blade belts of DB drill bit can make the machined hole have ideal surface finish without reaming, and achieve satisfactory machining time. (end)

Copyright © 2011 JIN SHI