CNC machining tool magazine optimization

Maschinenfabrik Reinhausen has optimized the CNC machining tool magazine. Tool preparation, intelligent magazine replacement, and a large amount of graphic information on the CNC have become the focus of innovation.

Figure 1 Maschinenfabrik Reinhausen processes approximately 8 million parts per year on 30 machine tools, using approximately 9,000 different NC programs for this purpose

Maschinenfabrik Reinhausen, together with the Motion Control Business Unit of the Siemens Automation and Drives Group, implemented the existing SAP structure and the Motion-Control-Information system (Motion Control Information System MCIS, see Fig. 2) a few years ago. Smooth flow of information. In order to transfer the NC program to the tool, MCIS DNC (direct digital control) and tool management MCIS TDI (tool data information) are used. Both modules are connected to the user's SAP system. In the second phase that is currently completed, the integration of tool management into the paperless CAM process has been realized. The highlights are: optimization of tool preparation time in the magazine; intelligent offload strategy for reducing unnecessary tool cycles; generating a large amount of information about the tool, improving process safety, and reducing management costs.

9000 parts processed in continuous replacement

Reinhausen processes more than 9,000 parts on more than 30 CNC machines in three shifts and continuous replacements, so that effective NC program management and tool management have a direct impact on production efficiency, especially to four stations. The machine tool of each tool magazine with 120 kinds of tools is optimized for the goal. This machine tool only needs to be adjusted on average in each work class. Each NC program contains about 12 tool changes.

Figure 2 Motion-Control-Information-System (CIS) MCIS TDI from Siemens A&D used by Reinhausen for paperless processes

Tool preparation time

With the continuous improvement of tool technology, the constant acceleration of feed rate, and the continuous acceleration of machine tool acceleration due to the continuous improvement of drive technology, it often happens that the tool processing speed on the spindle is faster than the speed of the tool magazine. The result will be Unexpected waiting time.

The wrong solution is to use the program to encode all the tools in fixed positions, pre-classify them in the correct order, and install them on the magazine. The magazine is based on the need to be filled up for each order, and then it needs to be completely emptied for the reason of magazine storage, but in this case, people will give up the calculation of the number of tools that may significantly reduce the tool cycle. The right way is to leave the frequently used tools in the magazine and simply add the missing tools. With regard to the assumptions of these mutually opposing optimization measures, Reinhausen and Siemens have achieved the following unity in their joint projects:

Reinhausen's post-processing program (MR-PP) calculates the exact tool change time for each tool and uses the device's raw dynamic data. Tools with tool change times below the maximum tool magazine runtime are defined as short-stroke tools. Other tools are considered as long-stroke tools. The ratio is about 30:70. Each short stroke tool and its following tools are grouped together by MR-PP. The configuration is maintained until a long-stroke knife is replaced. Next is a short-stroke tool. The group begins with the next group number, and so on. For each NC program, it is sometimes possible to have more than one group with short-stroke tools (this may result in a waiting time for the magazine) and a long-stroke tool (this magazine will be ready in time).

Tool identification for short strokes

For the pre-adjustment of the tool using the Saturn MVIS II Zoller system, the short-time running group receives the special identification via the MR-PP and in the form of a nominal data file. After tool presetting, Zoller-PP generates the actual data file and delivers the group configuration to the MCIS TDI.

The MCIS TDI codes all long stroke tools and loads them into any free position of the tool magazine.

MCIS TDI encodes all short-stroke tools as fixed bits and loads them side-by-side on the magazine.

The error between "parallel" here can also be within three knives. This ensures that the tool magazine is ready for every tool without waiting time, and that it is also possible to perform a perfect tool quantity demand calculation for unencoded tools in the chain library. In this way, the machining center operator can be supported by a large tool magazine and a host-based intelligent tool change strategy: When the magazine is full, the equipment operator must be on the tool magazine before a new task. Replace it. If there is no computer support, there is a risk that the replaced tool will be needed again in a short period of time. In addition, during the replacement process, people also need to prevent the risk of re-disassembling the knife group for a short time.

Figure 3 Detailed tool graphic directly in control

Calculate tools suitable for unloading

Therefore, Reinhausen's CAM data administrator can provide a function that calculates the most suitable tool for unloading. This calculation is started by a special function in the Sinumerik 840D control system on the device. The host computer executes the following program:

(1) Read the tool magazine with MCIS TDI.

(2) Read the SAP task schedule, that is, through the SAP interface, the host computer can "see" all the tools needed on the device in the following days and delete these tools from the list of tool magazines.

(3) Individually matched tools, such as adjustable and matched precision rotating heads, are also removed from the list.

(4) The remaining tools can be replaced accordingly, and they are categorized according to the last date of use. In addition, short-term runners are only allowed to be replaced as a group.

The resulting list of replacement recommendations is transmitted by the host computer online to the control system via a special function of the MCIS TDI. The operator feedbacks the replacement advice to MCIS TDI, and the optimized replacement process starts automatically.

The intelligent replacement work that has been implemented in previous projects, and the function of acquiring tool database data online has been extended to the smart replacement category. Through the intelligent replacement of MR-CM, the workflow has become "dynamic", and the tool placement work for the tool magazine has been optimized in the shortest possible time.

Higher process safety tool information

As soon as the tool magazine is changed, all other information of the tool is lost, whether manually entered or via the Sinumerik registration tool and Tool-Offset-Active-Files (TOA, Tool Compensation Documentation). Sinumerik's standard tool management is limited to a few basic information. Other information, such as part lists, tool text descriptions, indexing blade identifiers, plating, and push-in lengths, needs to be retained on the device in the form of paper.

MCIS TDI can be used to fill this information gap: The software module can provide a large number of database areas dedicated to each user, through the Zoller system can store the actual data file information required.

Display Pixel Graphics on the Control System

One special feature of MCIS TDI is that it can display Pixel graphics (JPEG, BMP, etc.) on the network path. The tool graphic generated on the front-end system (Figure 3) can be visually displayed on the control system directly through the set path. This type of graphic contains all the geometry and technical information of the tool. In order to automatically generate tool graphics from any tool management system, Reinhausen offers a set of tools that the user can set individually into their specific environment. At the same time, the use of the MCIS TDI for Zoller's actual data transmission has also become easier than simply using Sinumerik's DNC login tool. This is because the Zoller tool presets directly store its actual data in a virtual TDI database of the device. Only through the optimization of MR-CM and MCIS TDI, the tool preparation process for the short-term running knife The waiting time can be shortened by approximately 8 s per tool change. Thanks to the intelligent replacement strategy, the tool cycle time can also be reduced by approximately 10%, while the administrative expenses are also reduced by approximately 20%. The failure rate is lower and the process safety is higher, so the production efficiency also reaches a higher level.