KEYED JOINTS

Ever wonder how machine element which rotates with shafts, how are they joined? Well, there are many ways, but one of the most effective and easy way is to use a key. A key is a machine element used to connect a rotating machine element to a shaft. The key prevents relative rotation between the two parts and enables torque transmission.A key is used for temporary fastening. For a key to function, the shaft and rotating machine element must have a keyway, also known as a keyseat, which is a slot or pocket the key fits in. The whole system is called a keyed joint.They are used in many components like pulleys, clutches, gears etc. Like, most of machine elements, they are also of many kinds. I will here discuss the simple type of Keyways. You can use your Pro/E's, Solidwork's etc to design them in modelling and apply standard tolerances during drafting. Below is the picture of designing a simple standard key for a shaft.For the bores and for other kinds of keyed joints, you can look for over internet or various design books.

Machining: They are generally machined on shafts by using milling machines. The rotating tool of vertical mill removes metal from the surface of shaft.In the shafts they look like this.

Machining of square keyways in bore of shafts, gear, or pulleys etc is done by machine called slot machine. It uses a tool in the form of bit of HSS material, which can be grinded to desired dimensions to machine desired keyways in the bore. The tool moves up and down and machines the Keyway. Below are the photos of slot machine and its keyway tool.

The large Keyway being made in the bore of large spiral bevel gear of 5 module by slot machine.

RUN OUT ERROR OF GEAR TEETH:-Gear Meteorology and Measurement:

This error is used to know the run out of pitch circle of the gear.It is the error in radial position of the teeth.
Run out error causes various vibrations and noise in the gear mechanism. To completely remove it, the manufactured gear is hardened, and then grinded. Grinding removes this error completely, and hardening prevents it to get oval after gear mesh when used. One example of use of such gears is below in the photos.The gear in the photo is, used in pump for hydraulics. In order for gears to create the sufficient pressure, it should have no run out error.
There are various ways to measure it, such as computerized machines which work with air pressure and give whole reading of gear teeth profile and run out. Most often it is measured by indicating the position of pin inserted in each tooth space around the gear and taking the largest difference. Another way is, generally for fine pitch gears, to roll the gear with master gear on a variable centre distance fixture, which measure and record the change in the centre distance as the measure of teeth or pitch circle run out.
The method that I used here is a simplest one, and the most fastest. I used a screw gauge and measured the run out in each of group of three teeth, I selected the number 'three' for screw gauge to measure the error with MOT formula. The cutting and grinding of teeth was done in the company. The Reading was found to be 34.44 in each of group, and hence the run out was 0.

BRACKET (Sheet Metal)

The following piece I worked on, when a neighboring sheet metal company asked me for making the base drawing of the sheet metal part whose drawing was wrongly made by engineer due to the lack of the knowledge of how piece would be manufactured. He made the drawing of part, but didn't added the flat view, the base view, of the piece in the drawing sheet, which is required to make the piece on which die punches to produce a complete piece. It is a piece used in automobiles. I can not share the drawing of the piece as, I do not own the rights. But, here is the view of piece in Pro/E. Now in Pro/E, I made its parametric model, after which I transferred it to sheet metal file and on sheetmetal application of the software, I  unbent the bends on piece, one by one using various commands (4-3-2-1 on photos).In real life, it will be manufactured by a punch of die on plane sheet, after which other machining would be done.Below are the images on Pro/E and manufactured product.

SPIRAL BEVEL GEARS:- Transmission:

Pair of spiral bevel gears made from the manual milling machine! The pieces were successfully developed under the limited technical resources available in the company. The pieces were found satisfactory by customer, and they ordered more for manufacturing. The process of case hardening was done after the gears were machined. The company can now produce the gear with the teeth range of 10 to 150, and with the module range of 1 to 5.

The Spiral bevel gear of 5 module.