Milling machine to achieve the complex processing technology
This article describes the potential of functional integration for small and medium batch processing at a milling center. This kind of machining center can expand the laser welding technology, hardening processing and cutting processing or change the structure and other functions. The use of this process allows small tooling of individual tool steel casting tools and highly demanding titanium alloy or Cr-Co (chromium-cobalt) steel medical implant parts. The laser technology process and the partial processing of the workpiece are realized by a robot integrated on the machine tool. In this way, all the composite machining processes can be realized in a single clamping process by means of mechanical equipment. Based on milling machine with moving table The composite machine tool is based on a milling center with a mobile table structure type and is equipped with two rotary tables, a 6-axis robot arm and two laser processing units (a laser light source for continuous welding and high-efficiency welding and hardening. And a pulsed laser light source for energy). Since the welding and hardening process does not require the high precision of the machine tool, a space-saving 6-axis robot arm can be integrated on the equipment, which can improve the overall equipment utilization efficiency. The interface between the processing unit and the energy chain cannot be split, so the entire media must be transported through a hose that is constantly located on the processing unit. The hose is also used to unload the fiber. In addition to fiber optics, there are two wire lead-in systems, cooling water supply systems, process gas lines and signal cables. The hose is connected vertically to the machining unit via a swivel arm above the machine. The introduction arm on the one hand is responsible for ensuring the vertical orientation of the hose in the work area, on the other hand ensuring the specific orientation of the fiber optic and wire transmission systems. The mechanical interaction between the induction arm, the equipment frame, and the robot can be minimized by structural dynamic adjustment. Sliding door setting is easier to operate at the top For laser hardening, welding and cutting technology, the equipment uses a high-quality laser beam - 2.4kW fiber laser. The combination of these technologies, while taking advantage of process flow, also hides the potential dangers that threaten operators. A laser protection cover with the current state of the art and with probe monitoring ensures the safety of the operator (Figure 1). The front end of the device is the robot's protection work area, so no additional protective measures are required. Through the push-pull movable door of the laser isolation cover ceiling, the work area can be easily accessed to achieve the loading operation of the overhead crane. By using a high-efficiency fiber laser, it is possible to integrate multiple laser processing processes into a modular, interchangeable processing unit for the first time on the basis of a combined beam deflection system (laser scanner). The composite scheme is based on beam guidance and beam focusing using a 2D scanning system (Figure 2). The use of a beam deflection system with a polyhedral angled optics enables flexible machining of the surface of the workpiece being machined near the area of ​​the forward beam scanning. An approximately orthogonal beam tilt is achieved on the surface of the workpiece to be machined. In this regard, the intensity distribution that varies within the beam propagation range can be purposefully used to achieve different processing techniques and processing ranges. The focal intensity greater than 1 MW/mm2 is located above the material cutting axis and is used for local evaporation. In this way, single pulse drilling below 100 μm can be achieved in the millisecond range. In the direction of forward propagation, the intensity peak gradually decreases, and the laser beam on the processing surface is dispersed, whereby the focus of the workpiece surface becomes larger. In this discrete working area of ​​the beam, laser welding and laser hardened machining can be realized. In the case of continuous laser processing (cw mode) and power density <1 kW/mm2, most of the heat is introduced into the workpiece. This heat can be used for the hard-phase treatment of the phase transformation in the edge region. In this case, the surface of the workpiece is The degree of hardening can be locally increased (martensite hardening). In laser welding, this heat can be used to melt the auxiliary wire that guides the focus, and the metal layer connected to the parent metal is formed through the bath. On metal parts that are heavily loaded, this metal layer becomes a wear-resistant protective layer, or is used for structural update of parts in the case of controlled metal production (CMB). Using a 2D scanning system, adjustable track widths and flexible machining trajectories can be achieved in both applications. In the hardening process, the focus is scanned using a few hundred Hz laser and an adjustable width within 20 mm, and the robot can simultaneously focus the parts, thereby generating a machining trajectory. During the relative motion between the robot and the workpiece, the scan width can be set to match the width of the trajectory, so that a flexible hardened contour can be generated. In addition to the flexible processing trajectory, a uniform temperature distribution can be ensured by scanning the focus on the workpiece, which has a crucial influence on the result of the process. During welding, laser focus scanning can be used to influence the specific temperature distribution on the surface of the bath, whereby the surface stress can be locally adjusted and the width of the coating track can be adjusted within a certain range. Focal spot determines coating width For the implementation of the system technology, a vertical distribution (scattering direction) wire feeding system with a 2D scanning system (Fig. 3) is integrated in the compound modular laser robot cell, and the energy chain is vertically connected. Switching between the welding and hardening process or the cutting process requires activation or elimination of the wire introduction function and the opening or closing of the wire introduction nozzle inside and outside the flow range. Through the corresponding gyration energy of the wire inlet nozzle, the automatic conversion of the flow can be achieved, and the unfavorable trajectory profile during laser hardening and laser cutting can be reduced. In addition, in order to achieve a specific design structure after cutting, the composite machining unit uses a medium and low-power short-pulse laser device in combination with a 3D efficient beam deflection system. It is thus possible to generate a specific pulse operating structure (pw model) with a pulse peak power of less than 1 GW/mm2. Discrete structures in the 20 μm range cannot be realized by robots, but also require the machine to reach a certain accuracy. Therefore, the structure replacement system is changed to the machine tool in a modular manner through the interface of the spindle tool holder. An important factor in the successful use of composite devices is the design tool that provides the best support when users specify the use of traditional devices to complete a more complex process chain (Figure 4). When designing for machining in a complex machining center, the trajectory design is performed either for milling or laser machining on a CAM system. Here we need to expand the commercial CAM system and add corresponding modules to show the laser work flow. The trajectory design of the laser process is based on machining strategies for 5-axis and 6-axis milling ranges. The generated trajectory has process parameters to control the laser power. The design work is done cross-cuttingly, and the system generates various suggestions for the user based on the obtained process knowledge. From the generated data, the address memory is used for both device control (NC) and robot control (RC) to automatically generate runnable programs. For security reasons, each subprogram must be verified on the device via a simulation model before execution. Virtual control is used here to accurately simulate the actual control time. In combination with a dynamic model, various interference situations can be identified in advance. In the development of such complex equipment systems and the use of lower-cost standard components, a major challenge is the synchronization and the linkage of control components that communicate with each other using industry-standard Profibus (Figure 5). Composite machining center improves competitiveness For high-paying countries to maintain their ability to compete globally, an important condition is to achieve good economics in the processing of small and medium-sized parts. The complex machining center integrates modern equipment, laser systems, and modern process and control technologies, all of which provide critical conditions for economical and flexible machining. In the framework of the “High-paying State Integrated Production Technology†key project sponsored by the German Research Foundation (DFG), people have studied all of the above aspects and proposed the major requirements for equipment systems for processing complex products in medium and small batches; Taking the above-mentioned equipment system as an example, we explored the interrelationships in the system and the new, more competitive production chain adopted by this high-paying country in Germany. weihaimaideqi , https://www.weihaimaideqi.com
Figure 1 The front of the machine has a protective work area for robots. The operator's safety is ensured by a laser protective cover with sensor monitoring 
Fig. 2 The compound machining center adopts a 2D scanning system. This system can control laser guidance and focusing. Laser beam welding and laser quenching processing can be realized by discrete processing of the laser beam.
Divergent lasers for quenching 
Figure 3 The robot grabs the laser processing unit and guides the unit. The hot wire transport system and the 2D scanning system are connected to the laser processing unit. 
Fig. 4 The integrated design chain for laser machining and milling is absolutely necessary for the success of the hybrid technology solution. For milling and laser machining, the trajectory design is performed on the CAM system. 
Fig. 5 The complex machining center adopts the standard component of relatively low cost, it faces one important challenge is the synchronization problem of the control element, for this center uses the industry standard type Profibus