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Miscellaneous machine tools, gear cutting machines and equipment
News Release from: Costruzioni Meccaniche Caorle | Subject: Model CL132-5000 end-working machine
Edited by the Manufacturingtalk Editorial
Team on 01 September 2003
End-working machine takes on cylinder
variety
an end-working machine has been specifically designed in order to respond to the machining needs of an important French manufacturer of a variety of hydraulic cylinders.
The demand for the use of bars and tubes in various business industries has increased, with regards to high volume applications or for quality niche market products These two quite varied business fields require different types of products and specific production and working processes
This article was originally published on Manufacturingtalk on 22 Mar 2002 at 8.00am (UK)
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The end-machining is for a variety of different types of hydraulic cylinders, which is principally chamfering on both ends, the required installation of the machine is in a machining cell, where at the beginning of the line is located a saw to cut the cylinder bodies and at the end of it there is a lapping machine for the internal finishing of the cylinders.
After these operations the cylinders are moved to the welding phases, one side is closed by welding the bottom part and on the other end is welded the closing-flange, which drives the cylinder-rod in its movement.
"Conceived and designed to reply to a specific need." says Alberto Caorle, Managing Director of the company, "the CL132-5000 is structured with four NC axis and two machining units, but it was customized with regards to the main structure (it has a diameter range from 40 mm to 200mm maximum and a minimum machining length of 300mm and a maximum of 5000mm), with regards to the tooling and also of the automation, in order to respond to the needs of executing the end-machining with reference to the internal diameters, on different dimensions of hydraulic cylinder of their production, by means of a flexible solution, with high productivity level and a reliable one ¯.
The steel bed of CL132-5000 is an electro-welded and normalized structure made of a thick section heavy-duty steel plate, strategically reinforced for obtaining a maximum stiffness and rigidity.
The considerable length (approx.
8000mm) required a specific designing aimed to achieve the maximum rigidity for the whole length.
On the steel bed are positioned the two longitudinal "T" shaped guideways made of hardened and ground steel (the "T" is 100mm wide) and above them slide the cast iron longitudinal saddles units (Z1 and Z2 axis).
The left-side saddle unit only has a "working stroke" of about 200mm whereas right-side unit has a remarkably longer stroke as it covers the whole work-piece length of 5000 mm.
It was necessary to chose two considerably different ranges of stroke (please note: the standard concept of the classic end-working machines the two independent machining units are free to move towards the centre line of the machine) in order to set "zero" reference of the machine in respect to the same references of previous machining (saw process) and for the following process (lapping).
On top of the two longitudinal saddle units are mounted the saddles for the transversal movement (X1 and X2 axis); each one of the two transversal saddles has a work-piece centering unit and a maching unit.
The displacement of the above referenced saddles is driven and positioned by precision ball-screws and AC Brushless servo motors Siemens.
Customization for a higher added value - the two opposed centering units have been specifically designed in order to ensure perfect centering of the two extreme ends of the cylinders in respect to their internal diameter (this accurate centering is necessary to ensure that, after the lapping process the rod of the piston, once assembled in the cylinder, is able to move with a perfect barycentric movement).and they consist of two self-centering hydraulically actuated three-jaws chucks.
The two opposed machine spindle units permit the end machining of the cylinders by means of profile shaped tooling mounted on the ISO50 machining spindles (equipped with hydraulic rapid tool unclamping), the motor power of each spindle is kW 15.
The machining is performed dry without coolant to avoid any coolant contact with the surface of the workpiece because of the lapping process, which follows and which uses a special oil which cannot get contaminated with coolant.
The tooling used is customized for this type of machining.
The spindle cartridges are lubricated by permanent grease.
Because of the dry-machining process it was necessary to design a more powerful centralized lubrication system for the moving parts of the machine, which is carried out by metering higher quantities of oil with regards to the standard system.
On the two longitudinal saddles are positioned the self-centering jaws used for clamping the workpiece cylinders.
A specific study was necessary for the design of the clamping units.
The solution we have reached consists of a couple of independent self-centering jaws with "floating vices", which are an integral part of the overall design study with regards to the workpiece positioning and machining cycle of the cylinders within the machining cell and achieving in this way the best global result in terms of flexibility, precision and productivity.
The clamping strength of the "floating vices" can be adjusted with regards to the characteristics of the different types of cylinders, assuring in this way a proportionate clamping power for each range of workpieces and also suitable with the requirement of avoiding any deformation on the external side of the workpieces.
The workpiece cylinder is pre-clamped on the inside diameter at each end by the two opposed centering spindles, after which the external vice jaws clamp the outside diameter at each end in the correct position and then the centering spindles release the workpiece.
By means of the transversal movement the two opposed ISO50 spindles move into position for machining at each end of the cylinder.
The required machining (facing, internal chamfering, external chamfering and a short neck turning operation, one end only) is carry out by means of the movement along the "Z" axis and by using a tool-holder (with pre-set tooling) mounted on the ISO50 spindle.
The type of machining required causes a "problematic" type of chip, which is particularly long and curly and they may bunch up intertwine with each other and also wrap around the tooling and the workpiece.
We have solved this problem by using a pulsating machining programme, which allows a controlled cutting chip which can easily be handled.
In the absence of a coolant system (because of the dry machining), a blowing air system provides the complete cleaning of the working areas and moving chips to the evacuation chutes and the two opposed chip conveyors, one at each side of the machine.
CL132-5000 is equipped with a loading/unloading system integrated with the machine.
The loading device receives on double front arms the workpiece (cylinder) which has come from the saw system and, by a pair of rear arms unloads the machined cylinder, which it unloads on to an inclined table: the cylinder is now available for the further lapping machining phase.
Loading and unloading operations are simultaneously executed by means of the hydraulically system, which is electronically controlled.
The operating software for the complete automation was developed by Caorle.
The best compromise for productivity and versatility -"The CL132-5000," says Alberto Caorle " is a fast and versatile machine.
Thanks to the easy setting it is indicated not only for high volume productivity but also for the machining of a single workpiece and, moreover, with regards to the poor availability of trained personnel, it can be managed by a not so skilled operator." It is really important to underline the fact that, thanks to the important integration of the electronic and software aspects of the machining systems, and to the accurate studying of the tooling, the cycle times and the setting times are really low.
The handling (loading and unloading), the positioning on the jaws, centering and clamping of a 5000mm length pipe with diameter of 200mm, all these operations are carried out in aprox.
25 sec., with a placing repeatability of the workpieces within a couple of millimetres; the machining phase is aprox.
20 ö 30 sec., with a repeatability within 0,02 - 0,05 sec.; therefore the cycle time, floor to floor, for the end-machining of a cylinder body of the above stated dimensions is aprox.
1 minute.
The only handling of the workpiece, when the machining is carried out by using a lathe with a rest, needs more than 1 minute.
In order to achieve these results an important role has been plaid when designing the jaws, one of the most critical problem we have faced.
The target (and the main difficulty) was to obtain a sufficient range of "sensible movements" able to adjust the positioning of the jaws (without excessively forcing on the clamping position) on the contact clamping area but also keeping at the same time a sufficient rigidity in order to allow a proper clamping of the workpieces.
With regards to the previous stated target we had to develop a solution which had to take into consideration a perfect well balanced weight, in fact a structure too heavy could have caused a damping factor so high to be an obstruction to the achievement of the requirements in terms of precision, and this considering the strength needed to move the vices only for a hundredth of a millimetre.
An under dimensioning of the systems used for moving the jaws could have limited the frictions, but the so obtained system would not have been rigid enough to obtain the required results.
"The solution we achieved," explained Caorle, "brought us to realize customized equipment, which is constituted by a self-centering part and a floating part.
The first one carries out clamping in an automatic mode, and it is moved by two saddles displaced by means of a trapezoidal opposed step screw actuated by an hydraulic motor.
The two prismatic floating vices with two grades of "freedom" (a rotating one and the other one along the vertical axis) make perfect the operation of clamping, so that at the closing time of the vices the "V" shape of the prism is able to take position on two contact points in a self-adapting mode.
Once this position has been reached the vice is blocked by means of specific hydraulic clamping devices".
A fast set up time - "With regards to the change of the production program," continues Caorle, "the only operations to be done for the new set up of the machine are the following: load of the working program; execution of the longitudinal pre-alignment (automatically done by the NC unit) of the cylinder on the loading arm (the loading arm is able to "recognize" by itself the differences in diameter of the various type of cylinders in order to place them on the working axis position without having to execute pre-setting or further set up); the translation of the cylinder towards the working area; the penetration of the centering spindles into the cylinder: one spindle keeps itself stable in a position indicated by the NC in order to set the "zero" position of the workpiece meanwhile the other one, by means of a system of torque control, pushes the cylinder with a calibrated strength towards a proper position in order to correctly share the stock metal to be removed on both sides.
When the clamping of the cylinder has been done we are ready for the machining phase.
In order to reduce the set up time, my advise is to equip the machine with specific tooling for the whole machining processes and, in case of high quantities of production of a variety of different tubes, my advise it to invest some money in an adequate quantity of tooling, in order to get available the different types of tool-holder plateau ready to be installed each time is needed.
When necessary, the only substitution of the three jaws of the self-centering spindles, because of a change of production, can be executed in a really fast time, by means of simply unscrewing of a screw.
In some specific case it is useful to prepare the specific spindle jaws in order to further lower the cycle time".
CL132-5000 is equipped with a control panel with keyboard and customized NC unit for an easier and friendly programming.
Thanks to the parameterised programming (the machining programs can also be prepared off the machine), the operator has only to indicate the machining dimensions and the cutting parameters.
It is possible to learn the machining time, to program lot sizes of workpieces, to plan stops for the change of tooling and so on.
The safety protections are customized in order to be able to place the machine inside the machining automatic cell: partial covers protect from the swarf/chips coming form the machining area and photocell barriers protect for the whole length area of the machine.
In order to obtain easy and ergonomic access to the commands, all the manual commands for the displacement of the machining units, clamping and set up and the foot-pedals used for the hydraulic clamping of the spindles are doubled (that is, one for each machining unit).
Customized solutions for industrialization needs - "Our company," concludes Caorle.
"has been constantly growing thanks to the strategy of manufacturing small series of machines, but with high level of customisation.
Starting from the middle of the '60s, (when we began to manufacturer the end-working machines after a business period as a mechanic-work supplier for third parties), Caorle has always bet on creativity and with the aim to fulfil all customer's requirements, by using each time the available technology.
The process of development of our machines begins with the manual working cycles, then it goes through the realization of the first hydraulically actuated automations, it continues with the further design of the simultaneous machining of both ends by means of hydraulic movement (loading and unloading operations included), sequences managed by the PLC, machines equipped with the new generation of PLC supervisor for an easy and friendly programming and NC unit for the displacement operations, machines with multi-working heads, with two of four axis supervised by the NC unit.
At the beginning of the new millennium, because of the requirements for a further versatility, for a reduced cycle time and with the advantage of using standard tooling, Caorle has stepped forward by bringing the technology of a machining centre to the End Working Machine, obtaining in this way also machines with 6 NC axis and equipped with only one spindle each side working together with a tool changer.
In order to increase the production flexibility, we have also taken part to projects of "automatic machining lines" where the End Working Machines is loaded/unloaded by anthropomorphic robots or solution with portal robots.
Our company is now able to study, design and manufacture specific machines, equipment, and automations, optimizing the working cycle and executing complex operations on bars, forges and tubes.
Our mission is to continue the manufacturing of niche machines, always with the aim of supplying high quality products and with the target of replying to the customer's needs and with a production of modular machines conceived to be easily customized but with a lower impact on the total value of the machine.
It is because of the type of machine we produce that our main markets are the most industrialized ones: we export in Europe and in the USA, where is also located a branch conceived for that specific market.
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