|Bending - Course: Technique of Working Sheet Metals, Pipes and Sections. Methodical Guide for Instructors|
To ensure a trouble-free course of instructions, exercises, and vocational practice, it is necessary to prepare the training well, with the following measures to be taken:
2.1. Planning the Training in Bending Techniques
Proceeding from the total hour volume, the times for the individual training sections of this vocational unit should be planned in a differentiated manner.
It is recommended to draw up a time schedule for the subsequent training sections:
- for introducing the techniques in the form of instruction
- for necessary demonstrations
- for instructions to prepare the practical exercises
- for executing the practical exercises
- for recapitulation and controls.
While the hours are being scheduled, the following additional factors are to be taken into consideration:
- the trainees' educational level
- the training conditions
- the trainees' future employment
- the degree of difficulty of the training section.
The focus of each training section is always the acquaintance of practical skills and abilities by exercises, which will take the most comprehensive period of time.
2.2. Preparing the Instructions on Labour Safety
Before the practical exercises begin, the trainees are briefly instructed on the adequate handling of working means and given recommendations for an accident-free work. In general, those regulations are valid which are to be observed for manual techniques in hammering and straightening.
Especially, the following key points should be observed:
- Use only proper hammers - the hammer shaft must be tightly wedged with the hammer head.
- Select the correct striking plate with regard to the form of bending - a hard and inflexible surface is required.
- Workpieces to be campled have to be tightly fixed in the clamping fixture so that they are not torn away by the striking impact
- Always strike against the fixed vise jaw so that the vise screw will not be damaged.
- Mind your hands and head when working on presses.
- Work with welding torches must not be performed until the instructor has given the necessary instructions.
- Always observe fire protection - place ready water for fire fighting, do not work close to inflammable materials.
- Only bend sheet metals and sections over 8 to 10 mm thickness and pipes of more than ½" in a heated state.
- Use only dry sand as filler for hot bending of pipes to avoid steam formation.
Knowing about these hints is to be confirmed by the trainees' signing in the control book.
2.3. Providing the Teaching Aids
- The "Trainees' Handbook of Lessons - Bending" is to be distributed among the trainees according to their number.
- Illustrations contained in the Trainees' Handbook of Lessons and having a high indicative value should be used as visual aids (e.g. on flip charts, blackboards etc.)
- Workpieces showing well and badly performed bendings may be provided as visual objects.
- Particular tools and appliances not yet known to the trainees should also be used as visual illustrations, the same applies to brochures and photos of bending machines.
- If transparencies on bending are available, they should, in any case, be included in the instruction.
2.4. Providing the Working Means
- The "Instruction Examples for Practical Vocational Training - Bending" as theoretical basis for the practical exercises to be performed should be distributed according to the number of trainees.
- The basic material required for the exercises should be prepared and provided with the help of the specification of materials given in the "Instruction Examples ....." in sufficient quantity.
- The workshop should be checked whether or not it is completely equipped with tools, appliances, machines, measuring and testing means as well as auxiliary means as to the exercises planned.
- Recommended basic outfit:
· Steel rule, steel square, vernier caliper
· Steel scriber, centre punch
· Smooth files, band hack saw, hand-lever shear
· Machinists' hammer, light metal hammer, special hammers for sheet metal working
· Straightening plate, surface plate, vise
· Various intermediate plates and bending mandrels
· Drills and counterbores
· Hand screw press, bending devices, folding bench, rolling device
· Welding torch, dry sand
- Machines to be employed for bending have to be checked as to their serviceability with regard to labour safety before starting the exercises.
- For necessary drilling and counterboring operations, a table-type or column-type drilling machine with appurtenant clamping fixtures is required.
- Check serviceability of this machine prior to the practical exercises with regard to labour safety.