The Accuracy of Forming Rectangular Tenons by End-Pressing without Guiding Tooling

The article presents an analysis of experimental data on the manufacturing accuracy of tenon joint elements in pine workpieces produced by end pressing without using locating-clamping tooling. A specialized punch made of 45 steel was used as a forming tool, its geometric parameters are following: tenon thickness – 2.2 mm, mortise width – 2.0 mm, and height – 10 mm. Pressing was performed on a hydraulic press with a force ranging from 800 to 1100 kgf and a speed of 1.5 to 2 mm/s. The study aimed to experimentally evaluate the forming accuracy of rectangular tenons produced by cold end pressing to determine their compliance with requirements for workpieces intended for subsequent lengthwise splicing. Tenon thicknesses and mortise widths were measured on 18 workpieces. The tenons and mortises were conditionally divided into 2 groups: those located in edge zones closer to the workpiece side edges and those in the central zone. A one-way ANOVA in MS Excel was conducted to assess the influence of element position relative to edges on dimensional deviations. Results showed that mortise width and tenon thickness accuracy corresponded to IT11–12 grades, though edge elements on the right side exhibited deviations up to IT14. The position of mortises relative to workpiece edges had statistically significant effects on accuracy, while this hypothesis was not confirmed for tenons. The achievable accuracy for end-pressed tenon forming was predicted: 95 % of joint elements would comply with JS13 tolerance fields for mortises and js13 – for tenons. To improve forming accuracy, implementing clamping tooling to compensate for skewing and edge tenon springback is recommended, along with workpiece positioning correction using guide elements in the tooling.