Innovation, Technology & Skill Combine for a Gripping Solution

Design Challenges

Gripple is a fast growing award winning company involved in the design, manufacture and worldwide sales of their wire joining and tensioning devices. To meet the growing demand for this unique product, Gripple invested in their first fully automated assembly machine from SP Technology in 2005. The success of this project has ensured an ongoing working relationship between the two companies, with SP now supplying further machines, based upon WEISS indexing technology, to the Sheffield based manufacturer.

This latest machine for Gripple provides a highly flexible solution to the assembly of the 4 main components which together make an industrial wire hanger. The machine produces 3 product variants, each of which has unique dimensional characteristics for the pin and wire components. This presented a number of unusual design challenges to SP, not least the handling and manipulation of the wire and the demanding final assembly tolerances on the part. 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 into a 2.5mm diameter hole, prior to the wire being 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 intricate final assembly operation requires a pin to be assembled to a precise depth and SP developed an innovative solution to this problem using a combination of a vision inspection system and a servo operated press. As the pins are presented for assembly, the vision system is used to establish a datum by measuring each individual pin before the pin insertion operation takes place. The servo press is then used to assemble the pin to the precise depth by using the measurement data provided by the vision system.

Precise – high speed indexing at the heart of the machine

A major consideration for machine builders and end users alike, is a machine’s footprint. It is essential to strike a balance between the need to have the machine as compact as possible, whilst enabling easy access for operators and maintenance personnel. WEISS were able to make a positive contribution to solving this dilema using the TR series precision indexing ring. WEISS pioneered the indexing ring concept, which was quickly adopted by machine builders, as they realised the practical benefits of being able to make use of the space available on the inside of the ring. The 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 this instance the robot is located inside of the ring, making use of this valuable space and 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 12 position TR model 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 machine stations.

WEISS manufacture a complete range of rotary and linear indexing systems, plus fully programmable pick and place units, which can be applied to a wide range of automation applications. WEISS are one of an impressive list of professional partners and automation experts used by SP Technology, to assist in the development of innovative bespoke turnkey solutions for a wide range of production and process applications.