Highly automated spring end grinding machine

September 2017 — Developed in Germany, built by the Chinese subsidiary company: Wafios’ “G 450” is intended to cover wide customer circles and the most frequent tasks around the grinding of spring ends. A bulky option package serves special requirements.

The “G 450” is a single-plate spring end grinding machine for grinding both compression spring ends simultaneously using the crush-grinding or down-feed grinding technique. Its design combines proven technology with innovation: While the team of developers at Wafios draw inspiration from successful solutions from “G6” range, already on the market, it also pursued entirely new directions during the development process.

The machine’s basic version comes with eight axes – six servo-axes and two frequency-controlled drives – that are used for driving and down-feeding the upper and lower grinding wheel, driving the loading plate, the horizontal and vertical axes of the dressing unit, and driving the protective shield. It also features a high-performance cooling and dust extraction concept as well as a rigid dressing unit with two axes. Thanks to its protective devices, the G 450 meets the requirements for CE conformity, particularly when it comes to the harsher conditions associated with the type-C standard for grinding machines.

The infinitely adjustable rotating speed of the grinding wheels, which ranges between 35m/s and 50m/s, and the 7.5kW frequency-controlled three-phase motors for driving the two grinding spindles, enable the G 450 to achieve best levels of production output. The robust machine design for grinding springs and for dressing grinding wheels ensures that quality remains consistently good. The extraction channel has been positioned tangentially to the grinding wheel and thus improves the extraction of grinding wheel dust.

Other features of the basic version are laser sensors for automatic grinding wheel positioning, ensuring wear compensation, plus a spring length measuring device for in-process monitoring. The rigid design of the dressing slide ensures that a consistently high level of dressing quality is maintained throughout the entire stroke.

Even dressing at an angle is possible thanks to the control concept based on 2 servo-axes. The software package required for this is available to order as a separate option. In most cases, grinding wheels used in a dressing process are positioned so that they are parallel to one another (known as the down-feed grinding technique). However, this can result in springs in the outermost row of the loading plate being ground to a shorter length than springs that are positioned further toward the inside. Reason for this is the shorter grinding path that the springs on the inside of the loading plate experience. In other words: a smaller radius.  Positioning either one grinding wheel or both at an angle, so that the distance between the grinding wheels at the central point is 1mm to 3mm larger, solves this problem as the lower contact pressure exerted during grinding compensates for the longer path that the outer springs experience.

The extraction and ventilation concept, with an extraction channel installed in the perfect position, is a crucial part of what makes the machine's availability so good. It is positioned as far as possible toward the front, directly behind the dressing system, and tangentially to the grinding wheel in order to prevent deposits in the grinding room as far as possible. The design of the grinding room itself features optimized flow characteristics and ensures that the extraction volume is kept even at all times. Two fans generate an air shower for actively cooling the grinding room during the grinding process, making it possible to take advantage of maximum speeds while at the same time reducing.

Highly resistant to wear, the grinding table plates can be turned around in the entry and exit area and can thus be used on both sides. They have a significant role to play in cutting downtimes and operating costs. The pneumatically driven ejection flap enables the springs to fall down through the grinding table.

A special lift-out device makes it easier and safer to change the grinding wheels in an ergonomic way, while the optional balancing device helps the machine to perform its functions reliably by making it possible to minimize any imbalance in the flange-mounted grinding wheels as a preparatory measure.

Available as an option, the particulate deflector reduces and prevents deposits in the grinding room thanks to a special alloy that is applied to the G 450’s extraction channel lining. This feature also provides advantages due to the alloy components preventing the build-up of deposits, and the ability of the extraction system to remove dust from the grinding room. This means that no tools are required for removing deposits, machine availability is increased, and there is no need for frequent cleaning.

The machine is controlled using a 21.5" multitouch screen, and comes installed with the WPS 3.2 Easy Way control program. Featuring clearly presented screen masks, this control system is easy to use thanks to its intuitive operator guidance concept. It provides the operator with support during every stage of the grinding process – covering not only the spring input data, but also programming and monitoring of grinding cycles as well as grinding path control and sparking time. It also provides the electronic control elements for the down-feed grinding technique.

With the addition of the automatic loading unit, available as an option, the G 450 becomes a highly automated piece of equipment. This solution uses two buffer lines with three rows in each case to accommodate the loading plate, creating maximum availability. The associated handling robot simplifies the set-up process and ensures that operation is able to continue reliably. If the automatic loading unit is installed, there is also the option of equipping the machinery with a camera system for the reversing device on request, making it possible to align conical springs. The sorting unit is also available as an option.

Also available as an option, the automatic central grease lubrication system consistently increases availability by ensuring that lubrication is accurately and continuously maintained. Adding a teleservice connection also provides a rapid solution for keeping downtimes caused by machine problems to a minimum. 

Typical applications for the G 450 involve grinding valve and clutch springs in the automotive industry, but it can also be used in areas of mechanical engineering such as industrial and press springs (die springs). There are plans to unveil a version featuring two loading plates in the near future – allowing maximum production rates to reach as much as 5,000 to 6,000 springs per hour, depending on the spring geometry.

Wafios AG
Silberburgstrasse 5
72764 Reutlingen/Germany
Phone: +49 7121 146-0

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Partner Links
  • IWMA – International Wire & Machinery Association
  • ESF – European Spring Federation
  • ICFG – International Cold Forging Group