Gripple is the award-winning manufacturer of a novel wire joining and tensioning device that bears its name. Since the launch of the original product in 1988, over 500 new products and variants are now being sold across 75 countries. In order to meet this level of demand, some three years ago the company invested in its first fully automated assembly cell from machine builder, SP Technology. Since then, SP has supplied further machines to the Sheffield based manufacturer, the latest providing a highly flexible method of assembling the four main components of an industrial wire hanger.
The machine produces three product variants, each of which has unique dimensional characteristics for both pin and wire components. This presented a number of challenges for SP’s design team, not least being the handling and manipulation of the wire and the demanding final assembly tolerances.
To provide the required flexibility and to maintain machine cycle time, dual wire feeding and coiling stations are used. The coiled wire is located in the machine nest, before being picked up by an ABB robot. The robot delicately ‘threads’ the 2.0mm diameter wire through a 2.5mm diameter hole, whereupon it is hydraulically crimped to the main body of the part. A subsequent pull test ensures that the crimping operation has been successful before further component parts are presented and added to the assembly.
The final machine operation requires a pin to be assembled to a precise depth and SP developed a novel solution to this problem using a combination of vision inspection system and servo operated press. As the pins are presented for assembly, the vision system establishes a datum by measuring each individual pin before insertion commences. The servo press then inserts the pin to the precise depth, using measurement data provided by the vision system.
High speed indexing ring
A major consideration for machine builders and end users alike, is the machine’s footprint. It is important to strike a balance between making the machine as compact as possible, and enabling easy access for operators and maintenance personnel. Weiss helped SP solve this dilema with its TR series precision indexing ring. The indexing ring concept has been widely adopted by machine builders because there are practical benefits to be gained by making use of the space within the ring’s inner circumference.
Weiss’ TR series indexing ring not only helps to solve footprint and access issues, it also becomes the heart of the machine, transferring the components and sub-assemblies quickly and accurately between the various assembly and process stations.
In the case of Gripple’s latest machine, the robot is located inside the ring, not only making use of this valuable space but also allowing easy access to the machine assembly fixtures from the perimeter of the machine. Other automation elements such as component transfer units are also mounted on the inside of the ring.
This machine uses a twelve-position TR indexing ring to provide a high speed index with extremely smooth acceleration and deceleration, ensuring that parts can be indexed safely and securely between the various assembly stations.
Weiss can supply a range of rotary and linear indexing systems, plus fully programmable pick and place units. The company is one of several key automation partners of SP Technology, and actively assists in the development of bespoke machines for a wide range of production and process applications.