## 2 Materials and Methods
### Manufacturing Technology Project
#### 2.1.4 Design of a Low-Cost Bending Tool  
As a result of the low number of pieces required for the cutting blade, it was not appropriate to choose the standard progressive forming technology due to the high production costs. As the most economically advantageous solution, the utilisation of a screw press with manual control to its working zone a simple forming tool (bending tool) will be fastened consisting of the lower part of the bending tool 1, the upper part of the bending tool 2, the guide pillars 3 and the clamping shank 4 (see Figure 7). The upper part of the bending tool 2 is also the clamp plate, where the top is the tapped hole M20 to secure the clamping shank 4 for the press ram. The lower part of bending  
Figure 7: Design of the bending tool for the production of the cutting blades of the oscillating cutter (1—the lower part of bending tool, 2—the upper part of the bending tool, 3—the guide pillars, 4—clamping shank, 5—two locating pins, 6—auxiliary stop). tool 1 is simultaneously a foundation plate that will be clamped using the clamps to the press table. Both working parts of the bending tool move relative to each other exactly due to the guide pillars 3 (dowel pin hardened 10 \(\times\) 70--A--St according to [31] from chrome-vanadium tool steel, hardness (60 \(\pm\) 2) HRC, fine ground--tolerance h6, without surface treatment) with push-fit of H7/h6 without lubrication (Figure 7). The lower part of bending tool 1 was to be completed by two locating pins 5 (cylindrical pin of unhardened steel 3 \(\times\) 12 according to [32]) to establish and consolidate the blank using positioning holes around the circumference of the part of the cutting blade holder and the auxiliary stop 6 (cylindrical pin hardened 4 \(\times\) 20--A--St according to [31] of chrome-vanadium tool steel, hardness (60 \(\pm\) 2) HRC, fine ground--tolerance m6, without surface treatment) to prevent change of the blank position before landing of the upper part of bending tool 2. Due to an auxiliary stop 6, the blank inserted into the forming tool is held in a horizontal position so that it does not fall by its weight before the upper part of the bending tool 2. The geometry of the active parts of the bending tool was designed for bending with embossing, so the upper part of the bending tool 2 and the lower part of the bending tool 1 have an angle corresponding to the requested bend angle. This option is used only when bending on presses, in contrast to plain bending without embossing, when the tool parts have a universal shape and the upper part of the bending tool has a lower angle than the lower part of the bending tool, which has an angle corresponding to the requested bend angle. For the production of the upper part of bending tool 2 and the lower part of bending tool 1, steel 19,312 (alternatively, steel 19,573 can be used) was chosen. The clamp shank 4 for the press ram was made of steel 11,600. The mentioned materials were chosen according to their standard use for the manufacture of tool parts. The roughness of the work surfaces of the bending tool was designed at \(R_{\mathrm{a}}\) = 3.2 \(\upmu\)m. The blank for the production of the upper part of bending tool 2 has dimensions of (45 \(\times\) 50 \(-\) 155) mm, and the blank for the production of the lower part of bending tool 1 has dimensions of (45 \(\times\) 50 \(-\) 160) mm. The separate parts of the bending tool were machined on the five-axis milling machine. Because the main objective was to achieve a low cost of the forming tool for the small number of pieces of cutting blades specified, the heat treatment of the working parts of the tool was not proposed. Grinding of the tool parts after hardening was also eliminated. Guide pillars 3 and auxiliary stop 6 were designed as standardised cylindrical hardened pins, and two locating pins 5 were designed as standardised cylindrical pins from unhardened steel, so there was no need to produce any of them.