Veteran clampers summarize drilling steps and ways to improve drilling accuracy!

First, the basic concept of drilling

In general, drilling refers to the use of a drill bit in the product indicates that the processing of holes in a processing mode. Generally speaking, when the drilling machine drills holes in the product, the drill bit should synchronize the completion of two movements:

① primary motion, that is, the rotary motion of the drill bit around the axis (cutting motion);

(ii) Secondary motion, i.e., the linear motion of the drill bit along the axis towards the workpiece (feeding motion).

When drilling, because of the shortcomings in the structure of the drill bit, it will leave traces of the product processed, affecting the quality of the workpiece processing, and the machining accuracy is generally below the IT10 level, the surface roughness of Ra12.5μm or so, belonging to the roughing category.

Second, the operation process of drilling

Scribing

Before drilling, the first to understand the requirements of the drawing, in accordance with the basic standard requirements for drilling, the use of tools to draw the center line of the hole position, the center line must be clear and accurate, and the finer the better, after drawing the line to be measured with vernier calipers or steel plate ruler.

Drawing checking square or checking circle

After drawing the line and checking the pass, should draw the hole center line for the symmetrical center of the checking square or checking circle, as a test drilling check line, in order to drill holes to check and correct the orientation of the drilled holes.

Proof punching

Draw out the corresponding checking square or checking circle should be carefully punched sample punching. First hit a small point, measured in different directions of the cross center line several times, to see whether the punch is indeed hit in the cross center line of the intersection, and then the sample punching force to hit the right, round, large, in order to accurately centering the knife.

Clamping

Use a rag to wipe clean the machine table, fixture surface, workpiece datum, and then clamp the workpiece, according to the requirements of the clamping level, secure, and easy to query and measure at any time. Need to pay attention to the workpiece clamping method, in order to prevent deformation of the workpiece due to clamping. Do not want to engage in the bottom of the work, want to get rid of the status quo, want to learn UG programming, you can find the point of the crown of education teachers to learn CNC numerical control technology.

Trial drilling

Formal drilling must be test drilling before: the cross blade of the drill bit aligned with the center of the hole kind of punch eye drilling a shallow pit, and then visually check whether the shallow pit orientation is correct, but also need to keep correcting the deviation, so that the shallow pit and the check circle coaxial. If the violation is small, you can start drilling together with the force of the workpiece to the opposite direction of the violation of the push to arrive at the gradual calibration.

Drilling

Machine drilling is generally based on manual feeding operation, when the test drilling position accuracy requirements, you can drill. Manual feeding, feeding force should not make the drill bit bending phenomenon, to avoid the hole axis skewed.

Third, the method of higher drilling accuracy

Sharpening the drill bit is the beginning of everything.

Before drilling, you should choose the appropriate drill bit for sharpening. Sharpening the drill bit in addition to keep the top angle, back angle, cross cutting edge beveling angle is accurate, the length of the two main cutting edge is flat and symmetrical with the center line of the drill bit, the two main back cutter surface smooth, in order to facilitate the centering and reduce the roughness of the hole wall, but also should be cross cutting edge and the main cutting edge to do the appropriate repair and grinding.

Accurate demarcation is the foundation

Accurate demarcation with a height ruler, the first should be kept standard accuracy, demarcation of the line so that the angle of the needle and the workpiece demarcation plane constitutes an angle of 40 ~ 60 degrees (along the direction of demarcation), so that the lines drawn out clear and uniform.

To pay attention to the choice of scribing reference surface, the reference surface should be processed accurately, to ensure its own flatness and perpendicularity with the neighboring surfaces. After the hole crosshairs are drawn, in order to ensure that the drilling is easy to find the right, the use of the center punch in the crosshairs to punch out the center point (requiring the punch point to be small, the orientation should be accurate).

Correct clamping is the key

Usually, on the diameter of less than 6mm holes, if the precision is not high, the workpiece can be clamped in hand vise for drilling; on the 6 ~ 10mm holes, if the workpiece rules are fair, can be clamped in flat jaws, but should make the surface of the workpiece perpendicular to the spindle of the drilling machine. When drilling larger diameter holes, the vise must be fixed with a bolt pressure plate; for larger workpieces and drilling diameter of 10mm or more, the use of pressure plate clamping method for drilling.

Accurate finding is the key

Workpiece clamping end, do not rush to drop drill, should be the first to find the right.

There are static correction and dynamic correction. The so-called static correction, that is, in the drilling machine before the launch of the correction, so that the drilling machine spindle centerline and the workpiece cross line intersection point of the right, this method on the safety of beginners and convenient, more easy to grasp, but due to the failure to take into account, for example, the spindle of the drilling machine swing and other uncertainty factors, drilling accuracy is low. Dynamic alignment is to align the drill press after it is launched, and some uncertain elements are taken into account in the alignment, so the accuracy is relatively high.

Careful testing can not be missing

Inspection can accurately and timely find out the accuracy of the hole, in order to adopt the necessary measures to compensate.