Tube upsetters are used to hot forge the ends of tubes. This increases the wall thickness to provide the machining stock and strength necessary for joining the tubes together. The configuration of the tube end may be classified as EXTERNAL UPSET, INTERNAL UPSET, or INTERNAL-EXTERNAL UPSET.
The dimensions of the upset ends for oil country tubes are specified by API, Hydril, or others. Depending upon the type of upset, in one operation the wall thickness may be increased by a maximum of 50% for EXTERNAL or INTERNAL-EXTERNAL UPSETS, and by a maximum of 100% for INTERNAL UPSETS. Based upon these limits, some of the API upsets can be forged in one operation, but most API upsets require two operations. Most Hydril upsets require more than two forging operations.
Ajax tube upsetters are designed to accommodate tooling for two operations - the practical limit for a single heat. For those tube ends that require more than two forging operations, the first two operations are completed for the production lot, then the tooling is changed in the tube upsetter and the tubes are processed for the third and, if necessary, fourth operations.
Forging of tubes generates tremendous forces across the dies. The forces are substantially more severe than those generally resulting from the forging of solid bar stock, as greater die area is used to back up the forging operation. This forge area on tube upsets is normally about 3 to 10 times greater when compared to conventional forging machines. The forces required to prevent the dies from opening during the forging operations impose high loads to the toggles and the machine frame. Ajax tube upsetters are designed and constructed to withstand these forces and to provide reliable performance and minimal downtime.
In tube upsetting, the heading tool is long enough that the leading end is past the heated portion of the tube prior to the start of upsetting. The result is that a relatively long punch must be retracted from the tube after upsetting. This necessitates a long headerslide stroke, and provisions to grip the tube in the dies during a large portion of the headerslide stroke. Compared to conventional forging machines, Ajax tube upsetters have substantially longer headerslide stroke, stock gather and hold-on.
The available die length on Ajax tube upsetters is considerably longer than that on a standard forging machine. This provides for the increased grip length required when forging tubes- 4 to 6 times the tube diameter as compared to 3 to 4 times the solid stock diameter for conventional forging machines. The result is a more reliable grip.
Ajax has helped industry produce the highest quality forgings for more than a century, and our machines are the result of years of problem solving and innovative engineering. We invite you to review the special features which have helped make Ajax the leader in modern forging machines.