How to set tools on CNC 4-axis machining centers

1. Knife Point

The tool position is a reference point on the tool, and the relative movement of the tool position is the machining path, also known as the programming path.

2. Tool setting and tool setting point

Tool setting is the index control operator in the index control before starting the CNC program, through certain measurement means, so that the tool position point and the point of tool setting coincide. Can be used for tool setting instrument tool, its operation is relatively simple, measurement data is also more accurate. You can also locate a good fixture on the CNC machine and install the parts, the use of measuring blocks, rulers, micrometers, etc., the use of CNC machine tools on the coordinates of the tool. For the operator, determining the tool setting point will be very important and will directly affect the accuracy of the part machining and the accuracy of the program control. In the batch production process, but also to take into account the repetitive accuracy of the tooling point, the operator is necessary to deepen the understanding of CNC equipment, master more tooling skills.

(1) Guidelines for selecting tool setting points

Brief alignment on the machine tool, easy to check during machining, easy to account for during programming, and small tool setting faults.

The point of tool setting can be selected at a point on the part (such as the center of the part's locating hole), or at a point outside the part (such as a fixture or a point on the machine), but it is necessary to have a certain coordinate contact with the part's positioning datum.

Even if the part does not require high accuracy or strict program requirements, the machining accuracy of the selected tool setting part should be higher than the machining accuracy in other directions.

Choose a large contact surface, simple monitoring, machining process stability of the site as a tool setting point.

As far as possible, the tooling point and planning benchmark or process benchmark, to avoid the standard conversion lead to tooling precision or even machining accuracy, increase the CNC program or parts of the difficulty of CNC machining.

In order to advance the machining accuracy of the part, the tool setting point should be selected as far as possible on the part's planning or process benchmark. For example, to hole positioning parts, the center of the hole as a tool point is more appropriate.

The accuracy of the tooling point depends on the accuracy of the CNC equipment, but also depends on the requirements of parts processing, manual check on the accuracy of the tool to advance the quality of CNC machining parts. Especially in batch production to take into account the repetitive accuracy of the tool point, the accuracy of the tool point can be used relative to the coordinates of the machine tool origin value to check.

(2) How to select the tool setting point

For CNC lathes or mill-turn CNC machines, as the center orientation (X0, Y0, A0) has been determined by CNC equipment, the determination of axial orientation can determine the entire machining coordinate system. Therefore, only need to determine the axial (Z0 or relative orientation) of an end face as a tool setting point can be.

On the three-coordinate CNC milling machine or three-coordinate machining center, relative to the CNC lathe or milling and turning machining center messy a lot, according to the requirements of the CNC program, not only need to determine the coordinate system of origin orientation (X0, Y0, Z0), and with the processing coordinate system G54, G55, G56, G57, etc. to determine the relevant, sometimes also depends on the habits of the operator. Tool point can be located on the machined parts, can also be located on the fixture, but it is necessary to have a certain coordinate contact with the parts of the positioning benchmark, Z direction can be briefly decided by a brief detection of the plane of decision, and X, Y direction to determine the needs of specific parts according to the positioning benchmark and select the plane, circle.

On the four-axis or five-axis CNC equipment, increased the fourth, the fifth axis of rotation, with the three-axis CNC equipment to choose a similar point on the tool, because the equipment is more messy, with the intelligence of the CNC system, to provide more methods on the tool, according to the specific CNC equipment and specific processing parts to determine the tool point relative to the machine coordinate system can be briefly set to correlate with each other, such as the coordinates of the tool point (X0, X0, X0, X0, X0, X0, X0, X0, X0, X0). Y0, Z0), the contact with the machining coordinate system can be defined as (X0+Xr, Y0+Yr, Z0+Zr), the machining coordinate system G54, G55, G56, G57, etc., can simply be entered through the control panel or other methods. This method is very lively and skillful, which is very convenient for subsequent CNC machining. In learning UG programming friends can add QQ group: 304214709 to receive learning materials and courses.

Once the programming parameters input error, the machine tool bump, the impact on the accuracy of the machine is life-threatening. So on the high-precision CNC lathe, the bump accident should be eradicated.

(3) The most important causes of knocking occur:

a. Wrong input to the diameter and length of the tool;

b. Input errors to the workpiece standard and other relevant standards, as well as the initial orientation of the workpiece;

c. The machine's workpiece coordinate system is set up incorrectly, or perhaps the machine's zero point is reset during the machining process, and the changes occur, machine bumping mostly occurs during rapid machine movement, when the bumping damage is greatest and should definitely be avoided.

So the operator should pay special attention to the machine in the initial stages of the implementation of the program and the machine in the replacement of the tool at the moment, once the program is modified error, the tool diameter and length of the input error, then it is very briefly bumped.

At the end of the program phase, the NC axis of the back tooling action sequence is wrong, then there may also be a bump.

In order to avoid the above bump, the CNC operator in the operation of the machine, to give full play to the function of the five senses, to investigate the machine with or without abnormal movements, with or without sparks, with or without noise and abnormal noise, with or without sensation, with or without scorching smell. Found anomalies should be immediately intermittent program, to be resolved after the problem of the machine, the machine before continuing to operate.