DMG MORI, a manufacturer of machine tools, has developed a new automatic turning machine with multiple spindles that represents a technological revolution in producing turned and milled parts in both boring and bar machining.
After only two years of development, the company designed MultiSprint, which are multi-spindle automatic lathes that offer unlimited possibilities with enhanced efficiency and fast, precise, and diverse production processes. Key components to the series are readychain harnessed energy supply systems from igus, the Germany-based manufacturer of motion plastics. The machine is the first to combine a multi-spindle automatic lathe with SwissType technology, and with a Y-axis on each spindle position.
The Multisprint series combines the efficiency of a production turning machine with the precision of a turning machine and the complexity of a universal turning machine. The units make complicated turned and milled parts in the areas of bar machining without re-tooling the system.
“Customers are thrilled and immediately understand the concept of the new machine,” said Mikro Passerini, Technical Director at DMG MORI’s Italian location Gildemeister Italian S.p.A. “They especially like the ease of maintenance that the igus energy supply system enables.”
Changing requirements for turning machines
Customer requirements for modern turning machines have changed due to market dynamics and globalization. Machine tool makers now demand shortened processing and tooling times, reduced effort for process development and integration, and an ability to handle the increasing degree of complexity.
The new MultiSprint includes, for example, nozzles for fluid power equipment, implants for dentistry and shafts for motor vehicle manufacturing, which are just three of the complex components that can be made on high-tech machines. The result is a manufacturing solution for scalable requirements from initial series production to the high-volume production of complex workpieces.
The combination of three types of machine technology enables the customer to engage in completely new forms of production, setting new standards in productivity and efficiency. The customer enjoys maximum flexibility for the mass production of components with a diameter of up to 50 mm.
Harnessed energy supply system
The igus readychain, 2 m wide and weighing 750 kg, powers the machine. Among the first challenges for engineers was ensuring that the energy chain system fit into the housing of the machine.
The system includes eight energy chains, 64 electric cables and 73 hoses. The construction has a 1.8 m-high body for rotation. Six linear energy chains for driving the spindles protrude from the body like arms. Lifting the unit, which requires the assistance of two cranes, and connecting the readychain to the spindle drum requires about two hours.
During product development, technicians and engineers worked for nearly five months to design and assemble the machine, test it and send it on its travels. It was finally unveiled at EMO in Hannover, Germany, where it was presented as a revolution in mechanical engineering.
Heavy drum turns with extreme precision and maximum speed
The heart of the machine is the spindle drum with six spindles for simultaneous machining of several workpieces. The main spindles in the drum can travel up to 180 mm.
The drum moves the workpieces to the tools quickly and precisely. It only takes 0.65 sec for one of the six spindles to travel to the next position. For spindles to return to the starting position after machining has been completed in the six stations, the drum must turn 300° in reverse.
Despite weighing more than three metric tons, the drum completes the rotation in just one second. The rods are pushed out of the loader through the drum to get into position for machining.
6 energy chain systems from igus
The drum in the MultiSprint rotates in a range of 300° and consists of two rotation systems. The outer system includes hoses with a bend radius of 160 mm.
Twelve encoder cables and 12 servo cables from igus are guided on the inner circle. For each of the six linear chains in the drum, there are two encoder cables and two servo cables. One of the servo cables supplies the energy for the linear movements of the main spindles in the drum and one drives the spindle motor. They can move at a speed of 0.66 m/s and with a maximum acceleration of 10 m/s2.
The six energy chain systems can be plugged in individually due to distribution boards and are easy to maintain or modify. That feature was also one of the main requirements of the mechanical engineers designed the product.
In addition, the chains and cables of the readychain needed a relatively small installation space. It is important to ensure that the working space for the mechanic components behind the drum be as large as possible.
In summer of 2016, DMG MORI invited bids for the project, and ultimately chose to collaborate with igus.
“We have a lot of confidence in the many years of experience that igus has in the development of custom-made energy supply systems,” Passerini said. “As well as in the company’s extensive, high-quality testing facilities.”
The first meetings took place in January 2017, and two igus engineers visited Italy for a week. DMG MORI and igus engineers shared ideas and solutions regarding the design and suitable cables and hoses for supplying the drum with energy, data and fluid were chosen.
More than 800,000 test cycles
Engineers at igus had three months to develop the system. During development, a lot of value was placed on the modularity of the individual components. The linear chain systems can be plugged in and the sheet-metal parts designed by igus, for attachment to the machine, are made of several parts. This facilitates handling of the readychain on the customer’s premises and makes harnessing in the igus factory easier.
The igus specialists needed a little more than two days to complete final assembly of the chains with the harnessed cables and hoses. For fast production, it proved helpful that 95% of the readychain consists of parts directly made or procured by igus.
Assembly is also supported by the readychain rack, which is a metal frame with four different functions. It is an assembly tool for the connection of components at igus and makes the entire construction stable. The rack fits onto the load bed of a small truck. On the customer’s premises, the rack enables easy plug-and-play connection of the fully harnessed energy chain to the machine.
“Before delivery, the entire system was intensively tested for weeks on end,” said Lukas Czaja, Head of Industry Management Machine tools at igus. A specially developed test stand simulates the movements of the multi-spindle automatic turning machine. In testing in a realistic environment used, the readychain has already completed more than 800,000 cycles without any problems.
While a complex problem, DMG MORI found the right answers in working with igus. “The readychain solution from igus was the breakthrough for us,” Passerini said.