Improvement of the Method for Fixing a Punch in the Punch Holder

The punching process allows large quantities of parts to be produced at very low cost. This paper studies how the technique used for fixing a punch can be improved in order to increase productivity before punch fracture, which results in large numbers of parts failing to be produced, thus creating a significant shortfall. In this context, the study deals with an industrial case, specifically the manufacturing (metal sheeting and metal forming) of a connector made of stainless steel. A broken tool is first analyzed in order to identify the source of the premature breakage. Then, the tool and the process are modeled using finite element analysis (FEA) to act as a reference. Then, the improvements in the geometry and fixing method, intended to increase the tool lifespan, are assessed and modeled using FEA. Finally, the modified profile with only one central hole proves to be very efficient.

Impact of a Punching Process on the SyRM Iron Loss: SPICE Model as an Effective Tool for Iron Loss Modeling

Many technologies for cutting the magnetic laminations, from which electric motors cores are built, change material properties, among which are magnetizability and iron loss, thus affecting the motor parameters such as motor efficiency. This problem is particularly important for low-power motors, in which the dimensions of the magnetic circuit elements are relatively small. The correct estimation of the motor efficiency is important as early as at its design stage. This is possible when the correct material characteristics are used. This knowledge and analytical model enabling fast estimation of material properties (depending on the actual size) are necessary for engineers, who design electrical motors by analyzing many solution variants in a short time. The author proposes an analytical model of changing material properties, implemented in SPICE software. Its effectiveness was compared with measurement results while being a competitive solution in relation to other analytical models. The proposed SPICE model allowed evaluating material properties for lamination of any width. In the end, the knowledge concerning the material properties was used to calculate the iron loss in the stator of the SyRM motor, showing the need to use the material characteristics calculated for the specified width of the core piece.

Optical inline monitoring of the burnish surface in the punching process

Punching is a wide-spread production process, applied when massive amounts of the ever-same cheap parts are needed. The punching process is sensitive to a multitude of parameters. Unfortunately, the precise dependencies are often unknown. A prerequisite for optimal, reproducible and transparent process alignment is the knowledge of how exactly parameters influence the quality of a punching part, which in turn requires a quantitative description of the quality of a part. We developed an optical inline monitoring system, which consists of a combined imaging and triangulation sensor as well as subsequent image processing. We show that it is possible to capture images of the cutting surface for every part within production. We automatically derive quality parameters using the example of the burnish height from 2D images. In addition, the 3D parameters are calculated and verified from the triangulation images. As an application, we show that the status of tool wear can be inferred by monitoring the burnish height, with immediate consequences for predictive maintenance. Although limited by slow images processing in our prototype, we conclude that connecting machine and process parameters with quality metrics in real time for every single part enables data-driven process modelling and ultimately the implementation of intelligent punching machines.

A Coupled Eulerian-Lagrangian Simulation and Tool Optimization for Belt Punching Process with a Single Cutting Edge

The objective of this paper is to analyze the belt punching process with the use of a single cutting edge and discuss the influence of geometrical features of the piercing punch on the perforation force. Two basic shapes of the piercing punch with a single cutting edge were tested: tools with the blade pointing inside or pointing outside. The analytical models of the stress distribution in the shearing cross sections were derived for both punches. The presented model, along with the series of empirical tests and Coupled Eulerian-Lagrangian simulation, was used for finding the effective geometry of the piercing punch with a single cutting edge for the belt perforation. The geometrical parameters taken into consideration for the tool optimization were the following: angle of the blade, thickness of the wall and diameter of the piercing punch cutting edge. The obtained results show that changing these parameters has a significant influence on the perforation force necessary to execute the machining process and affects the quality of the holes in the perforated belts. The most important geometrical features of the hollow sharpened punch are the angle and the direction of the blade, which change the force distribution and, as a result, the mechanics of the process.

Analytical Model of an Induction Motor Taking into Account the Punching Process Influence on the Material Properties’ Change of Lamination

The technologies of cutting the cores of electric machines change the magnetic properties and the loss of the electrical sheets used, affecting the machine’s parameters, mainly power losses and efficiency. This is particularly important in the case of induction motors, which are a significant consumer of electricity. Therefore, the problem of increasing their efficiency is important from the point of view of environmental impact. The article presents a method of approximating a material’s magnetic properties based on the results of measurements carried out with specimens of various widths. The presented method allows for an approximate representation of the changes in the structure of the material caused by the cutting technology. It is used in the analytical method for calculating motor parameters, and gives results that are in good agreement with the measurement. This method can determine the operating parameters of electrical machines of various sizes and rated powers.