The manufacturing of springs is a metalworking process consists of several stages. And one of these stages involve the use of a spring grinding machine to grind the springs. When a spring (usually a coil of stainless steel) is made, it is first placed onto a designated former, and is then bent into the desired shape by the former. Then, the top and bottom of the spring is ground flat.
There are three basic types of grinding machines used to grind springs: crash grinders, crush grinders, and end grinders:
● Crash Grinders: This unit allows springs to pass through between the rotating disc grinding wheels on a rotating table. The grinding wheels are positioned a certain distance apart from one another. The entrance guides compress the springs slightly when the springs enter the wheels.
● Crush Grinders: This unit looks very similar to crash grinders, but works a little differently. The grinding wheels are positioned flat and parallel respectively to each other. The grinder also has a rotary carrier in which the springs are placed and passed between the wheels multiple times as the top wheel is fed down.
● End Grinders: This unit is mostly used when only a single end of the spring is required to be ground, or when the spring is too big to fit into a conventional spring grinding machine. These machines are normally equipped with horizontal spindles. The springs are held in a way that they rotate across the face of the grinder.
To grind springs with optimum precision, the grinding machine must be proper set up. The grinding heads of the unit must be aligned properly. For a unit with vertical spindle, the bottom head is usually aligned first, and the head is aligned to the rotary fixture on of the feed wheel. Generally, a straight edge is clamped to the rotary fixture and the feed wheel is removed from the fixture. The lower head is then raised so that the head can be positioned parallel to the straight edge. The measurements can be taken at any location by rotating the wheel collar, and the measurements should all be identical. Then, the lower head is aligned to the upper head, and the wheel collar of the lower hand is also aligned to that of the upper heard. This can be achieved by using a dial indicator that is held on the lower wheel collar. Both head should be aligned to the rotary feed wheel exactly when the above steps are completed. Now you can proceed to grinding the springs with the heads being appropriately configured.
A spring grinding machine is composed of an abrasive wheel, a work holding device known as a chuck with cylinder powered basis. And a reciprocating or rotary table is also fundamental. The chuck item will hold the material in place while it is being worked on. It can do this one of two ways: Ferro-magnetic pieces are held in place by a magnetic chuck, while non Ferro-magnetic and non-metallic pieces are held in place by vacuum or mechanical means. These are the basic components. To grind springs, the spring grinding machines have to have other corresponding fixtures for the formed spring items. With the firm fixture, springs can be ground flat and processed well.
When selecting a grinding wheel, you need to understand both the components and the relevant variables. For instance, speed is one of the key variables that determine the grinding result. To start with the basics, know that the grinding wheel is essentially composed of bond and abrasive grain. The first thing you should consider is the hardness and size of the grain, which defines the type of abrasive in the wheel. The grains come in a variety of sizes (i.e. grit) denoted by a number. The larger the number, the smaller the grit size, and vice versa.
With abrasive grain covered, we now touch base on bond. Bond is basically a glue that holds the grain in place. You’ll typically be choosing from two of the most common types of bond called resin and oxychloride, both of which have their own benefits and disadvantages. Resin is a stronger type bond that is typically used for the manufacture of abrasive discs, and is characterized by the relatively short curing time. Oxychloride bond is typically made with added strength. One key advantage of the oxychloride bond over resin is its superior tolerance to high temperature. This is especially desirable to the spring grinding process in which coolant is usually not present.
Following the above, knowing how to control and manage the heated spring grinding process is very important. When grinding springs at high temperatures, the material tends to become weakened and is more inclined to corrode. This can also result in a loss of magnetism in materials where this is applicable. The grinding wheel is not limited to a cylindrical shape. The shape can be different and can have a myriad of options that are useful in delivering different geometries to the object. The straight wheels can be dressed by the operator to produce custom geometries.
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