What is a twist drill

Twist drill is a tool for drilling round holes of workpieces by rotating cutting relative to a fixed axis. It is named for its spiral-shaped chip holding groove, which resembles a twist. Spiral grooves have 2, 3, or more grooves, but 2 grooves are the most common. Twist drills can be clamped on hand or electric hand-held drilling tools or drill presses, milling machines, lathes and even machining centers. The drill material is usually high-speed tool steel or carbide.

How to use twist drill

1, the twist drill should be packed in a special packaging box to avoid vibration collision with each other.

2, the diameter of the drill should be measured with a non-contact measuring instrument (such as a tool microscope, etc.) to avoid cutting edge contact with the mechanical measuring instrument and be hurt.

3, when in use, remove the drill from the packaging box should be installed in the spring clamp of the spindle or automatically replace the drill tool library.

4, often check the concentricity of the spindle and the spring collet and the clamping force of the spring collet, the concentricity is not good, resulting in small diameter drill break and large aperture, etc., the clamping force is not good, resulting in the actual speed and the set speed is not consistent, and the collet and the twist drill slip.

5, the depth positioning of the CNC machine tool using the positioning ring must be accurate when it is installed, such as the length of the drill installed on the spindle without the use of the positioning ring should be adjusted to be consistent, and the multi-spindle drilling machine should pay more attention to this point, so that the drilling depth of each spindle should be consistent. If the inconsistency may cause the drill bit to drill into the table or fail to drill through the board resulting in scrap.

6, can use 40 times stereo microscope to check the drill cutting edge wear.

7, always check the spindle press foot. The contact surface of the press foot should be horizontal and perpendicular to the spindle, and cannot be shaken to prevent broken drilling and deviation holes in the drilling.

8. The clamping length of the fixed handle twist drill bit on the spring clamp head is 4-5 times the diameter of the drill handle to clamp firmly.

9. The substrate lamination, including the upper and lower plates, should be positioned firmly and flat in the one-hole and one-slot positioning system on the drilling machine's workbench. When using the adhesive tape, prevent the drill bit from sticking chips on the tape, which may cause chip removal difficulties and drill breakage.

10, the suction effect of the drilling machine is better, the suction wind can reduce the temperature of the drill, while taking away the dust to reduce the friction generated by high temperature.

11, timely regrinding can increase the use of twist drill and regrinding times, extend the life of the drill, reduce production costs and expenses.

How to grind a twist drill

"Less grinding" is first of all "not grinding", get the drill in a hurry that is grinding, must be blind grinding. Only put in a good position before grinding, in order to lay a solid foundation for the next step of "grinding", this step is very important.

Here use four phrases to guide the grinding process, the effect is better.

Formula one: "The cutting edge is balanced against the wheel."

This is the first step in the relative position of the drill and the grinding wheel, and often students rely on the grinding wheel without leveling the cutting edge. I'm sure it won't grind well. The "cutting edge" here is the main cutting edge, and the "leveling" means that the main cutting edge of the grinding part is in a horizontal position. "Wheel face" means the surface of the grinding wheel. "Lean" means to get closer together slowly. The drill should not touch the grinding wheel at this time.

Formula two: "Drill shaft oblique release front Angle."

Here refers to the position relationship between the drill shaft line and the grinding wheel surface. "Front Angle" is half of the top Angle of 118°±2o, about 60° This position is very important, directly affecting the size of the bit top Angle and the shape of the main cutting edge and the cross edge bevel. To remind students to remember a commonly used 30°, 60°, 90° triangle plate 60° Angle, students easy to master. Formula 1 and Formula 2 both refer to the relative position of the drill before grinding, the two should be taken into account, do not ignore the bevel Angle in order to straighten out the cutting edge, or ignore the bevel edge in order to straighten out the oblique axis. In practice, these mistakes are often made. At this point, the drill is ready to contact the grinding wheel with the correct position.

Formula three: "Sharpen the back from the edge to the back."

This refers to the slow grinding from the edge of the bit along the entire back tool face. This facilitates heat dissipation and sharpening. On the basis of stable consolidation formula 1 and 2, at this time the drill can gently contact the grinding wheel, a small amount of grinding, grinding to observe the uniformity of the spark, to adjust the pressure in time, and pay attention to the cooling of the drill. When you start grinding again after cooling, you must continue to place the position of formula 1 and 2, which is often difficult to master when you first learn, and often can't help changing the correctness of its position.

Number four: "Swing your tail up and down."

This action is also very important in the grinding process of the drill, and often students turn the "up and down swing" into "up and down rotation" when grinding, so that the other main edge of the drill is destroyed. At the same time, the tail of the drill can not be high above the horizontal center line of the grinding wheel, otherwise the cutting edge will be blunted and can not be cut.

Twist drill maintenance method

1. When the twist drill is in use, first insert the bolt joint of the transverse component into the directional slot of the movable connection nut of the drill bar, tighten the connection nut in the counterclockwise direction, and then insert it into the soil in the predetermined drilling area with hand pressure. Each rotation of about 200~250 mm to lift the drill hole up (if too deep lifting will be very laborious and inconvenient), pick off the drill spiral soil, this soil is the distance from the lot of the soil sample.

2, the reciprocating work to 1 meter, it is necessary to continue to drill deep, should be clockwise to loosen the bit part of the connection part of the nut to remove the transverse handle, the additional second drill rod part of the bolt head part of the connection into the drill part of the active connection clockwise to tighten the connection nut, and then the horizontal parts and drill rod better than to continue to work, three, four, five sections of the same until the work is completed.

3, twist drill pipe is made of Pu wall seamless steel pipe, so it is not suitable for use in hard soil areas.

4, after each use should be washed, dry, coated with anti-rust grease, to prevent rust.