Hydraulic chuck - lathe .. how it works

     Hydraulic chuck with three jaws clamped on the material (or expands inside the material) giving some workpiece mounting with adjustable clamping force. The adjustability is important because of the nature of the workpiece, cutting or technology. Hydraulic control improves the production process by being able to open and close the jaws from the program (eg. M68 and M69). This gives you the ability to automate processing with automatic barfeeder (eg. long rods).
   
     The principle is quite simple and the most complex element is a hydraulic cylinder with rotary connector. The cylinder is at the end of the spindle shaft on the opposite side of the chuck. Inside the shaft is a drowtube - connecting piston of cylinder with moving parts in the holder, that the cam transfer the force to the chuck jaws.

All photographs and texts on this site are my own and I reserve the exclusive right to the use and publication.

Geometric measurements - milling machine spindle BT40

     Spindle measurements - checking condition and accuracy. The measurement procedure requires proper equipment to provide meaningful results.
 
      Measurements of runout using a testbar BT40:

     In order to avoid overlapping of testbar runout and spindle runout measurements must be taken at least four angular positions relative to the spindle stem (rotate 90 degrees testbar in taper of spindle).
 
      Measurements runout on the taper and the contact surface with the use of ink:

     Force measurement tools holder:

     It is also important balancing of the rotor, such an operation can be carried out in its own bearings of the spindle (without disassembly directly at the machine) for radial vibration measurement and compensation. I will try to describe the procedure in the following entries.

     All photographs and texts on this site are my own and I reserve the exclusive right to the use and publication.

Amateur milling machine.. Components

Linear Guideway
 
     The realization of the motion along the axis of the machine allow the guides that restrict freedom of movement in all directions except one, which runs along the axis. This solution may be plain, as is the case in conventional machine tools, or by using the linear guide of the rolling elements.
Browsing through the available offers in terms of their applicability to the construction of the plotter selected several solutions of linear guides and are shown below:
 
-Low Profile - the best solution (used in the professional machines) but also the most expensive.

- Shafts Precision with linear bearings in closed cabinets - a solution that many opportunities (used in professional machines, but not as part of implementing the major movements of the work) at an affordable price.

- Precision shafts supported with linear bearings in housings open - a solution similar to the previous but for greater rigidity same track.

 

 

Screws

     Propeller is a very important element of the drive, as responsible for the implementation of feed motion. A very good solution is to screw with ball screw. The efficiency of their operation is significantly higher than the efficiency of the sliding bolt. When designing the drive ball screw should be borne in mind that the screw is not self-locking due to the high efficiency. The drives should be used vertical slide inhibitory circuits, which in the absence of voltage collapse prevent uncontrolled carriage machine. The disadvantage of this type of screw is mainly price, up to 15 times greater than in the case of trapezoidal threads.

 
-Ball screw

-Trapezoidal screw

Drive motors and couplings

     Axis feed drives in modern CNC machines are operated by electric motors or servo motors equipped with a feedback system. The controller sends a signal to the motor while the defeated feedback on the way back to the controller to verify the correct execution of movement. This solution is very accurate and reliable, but also expensive. The amateur machines are being used stepper motors. Characterized by a high frequency step up to 16 kHz, while maintaining high accuracy angular displacements. Depending on the construction of the engine of this type, each rotation of the shaft needs to be sent from the controller the appropriate number of pulses (steps). With the increase in the number of steps per revolution increases the accuracy of the positioning. This solution is cheap, gives you the opportunity to work with great accuracy, but its disadvantage is the possibility of losing steps by engines.

-Servomotor with Inverter

-Stepmotor

-Couplings

 Photos components are only an example taken them from public sources online.

CNC for amateurs, build your own machine!

          Cutting as a manufacturing technique is the basis of production capacity in mechanical engineering. Numerically controlled machines give a lot of rapid, reproducible and fully controlled manufacturing. In commercial professional machines are used, but even in a home environment, it is possible to realize computer-supported production process. To get to know about and understand the aspects associated with the CNC should take up the challenge of building your own machine.
          Going through the construction process, from initial concept selection to specific projects and their implementation can gather a lot of knowledge of CNC, with having fun.
          
          My project:

           And its implementation:

          Browsing on the market offers plotters can meet a large discrepancy rates between devices with similar geometrical parameters. This is due to differences in the components used. Selected elements that determine the price, such as linear guides, screws or drive motors provide the basis for ensuring technological capabilities. Knowing the needs arising from the planned destination machine we are able to appropriately chosen components. In the next post I will present a comparison of facilitating the choice of components.

             All photographs and texts on this site are my own and I reserve the exclusive right to the use and publication.