I -.., CYLINDRICAL PRODUCTION GRINDING MACHINE
The 21 U fnd 21 P series of grinding machines were designed specifically for grinding workpieces that require longer center distances than was formerly available on the 2U and 2P machines. The 21 U is a universal production machine featuring a swivelling wheel head slide mounted on a large swivel base, allowing for the most suitable infeed angle to be used for grinding both faces and diameters simultaneously. The 21 Pis a production type machine with wheelhead slide fixed at right angles to the table ways. The heavy duty wheelhead and spindle, support a 30" diameter wheel up to 8 3 / /' wide. The bed is of extremely rigid construction, strengthened by 3 heavy longitudinal walls extensively ribbed together to form an inflexible base providing rigid and accurate support to the table and wheel head...
I _.;< THE WHEELHEAD is a self-contained unit with its own automatic lubricating system. The nitrided grinding spindle is rigidly held in multisurface bearings of our own design. These bearings provide smooth, vibration-free rotation and the spindle cannot float regardless of the load applied. Thrust is taken by special ball thrust-bearings designed to absorb the high pressure generated when angular plunge grinding or when face grinding with the side of the wheel. THE UNIVERSAL WORKHEAD is a very rigid unit equipped with a swivel base and a combination live and dead spindle. Since the workhead swivels, taper work can easily be performed. The workhead spindle is symmetrical with an internal taper in each end. The workhead can, on request, be equipped with double sided spindle drive making it suitable for use on the left or on the right side of the table, even when grinding with dead spindle. The drive is transmitted through V-belts from a mechanical speed variator giving a high torque at all speeds. THE DEAD SPINDLE WORKHEAD If the machine is to be used exclusively for grinding between centers, then this workhead is the most suitable. Its rugged spindle is symmetrical with an internal taper in each end. If both straight and angular infeed grinding operations have to be performed, double sided spindle drive can be supplied as an extra equipment, making the conversion of the workhead from left to right hand operation a very quick and easy matter. For increased stability, this workhead has no swivel base, but is clamped directly to the table... THE ~HUCKING WORKHEAD is specially designed for chucking work. A heavy rotating spindle is fitted and the spindle nose is built according to ASA-A1-8". No separate chuck mounting flange is required, the chuck being mounted directly onto the spindle nose. This workhead can be swivelled 90 degrees. Its rigidity combined with the heavy spindle having an incorporated chuck flange and widely spaced special roller bearings, provides a great load carrying capacity without loss of accuracy. THE TAILSTOCK is also heavily built and its barrel is located in adjustable bushings. The possibility of setting the barrel clearance to a strict minimum provides better stiffness and eliminates troublesome deflections. The pressure on the denters can be adjusted depending on the weight of the workpieces. As extra equipment, the tailstock can be supplied with pedal operated hydraulic barrel retraction. The retraction is automatically locked when the grinding wheel is in the advanced position. 3
The previously described basic machines model 21 U-A and 21 P-A can be equipped with various additional units. Their designations are modified according to the units supplied, by the use of the letters B, CorD instead of A. The equipment included with the various models is specified in its respective descriptions. INTERNAL GRINDING ATTACHMENT The machines, of which the basic model is designed for external cylindrical grinding, are in this version equipped with an internal grinding attachment. This hinged attachment is placed on top of the wheelhead and therefore does not interfere when the machine is used for external grinding work. The attachment is also equipped with its own spindle drive motor as well as with a separate feed making it easy to grind parts, both externally and internally in one set-up. Also included with the models 21 U-B are an internal grinding spindle, a chuck, a 3-point steady rest, a dressing device and the coolant piping and nozzle required for internal grinding. technical Spindle holder bore diameter........ inch 3 DATA Clamping length of spindle................ inch 6 1 h lnfeed length.......................... inch 4 Min. di.stance between. exterhal and internal grinding spindles... inch 10 1! GAUGE SIZING The basic machine is in this version equipped with an automatic gauge sizing system. This system consists of an electro-hydraulic infeed unit, an air-electric or electronic control unit and a grinding gauge. The electro-hydraulic infeed unit provides the following automatic functions: 1. Changing of infeed from coarse to fine feed 2. Stopping of infeed 3. Adjustable spark-out time 4. Retraction of wheelhead rapid traverse and infeed. The control unit includes an amplifier and an indicator, which constantly registrers the workpiece size measuring by the gauge. Two adjustable electrical contacts are provided, the first contact being used as a pre-size limit for changing from coarse to fine feed while the second contact or on-size limit retracts the wheelhead when the part has reached final size. Signal lights on the control unit indicate the outgoing signals. GAUGE HEAD The previously described hinged caliper gaug e included as standard with the C models can, on request, be replaced by an automatic slip on gauge head. This gauge head is table mounted and actuated by the hydraulic system of the machine. J 1 The grinding gauge is a hinged type caliper gauge which slips on the workpiece being ground. The caliper gauge has one fixed and one moving measuring point. The, moving point follows the diameter reduction of the workpiece and its movement is transferred to the measuring unit. From the measuring unit, the signals are transmitted to the indicator unit, where they are amplified, shown on a large dial and converted to electrical signals for control of the machine. The electro-hydraulic infeed unit is provided with its own electrical contacts so that automatic infeed grinding can also be carried out without the gauge sizing equipment. In this case,.final size of the workpiece is given by a positive stop. 4
1I. I Profile depth = 1'12" Profile cam Direction of diamond infeed r Direction of wheel head infeed ------~ Grinding allowance =.010" PROFILE DRESSING DEVICE The previously described machines models 21 U-C and 21 P-C are.. in the D ve rsion, equipped with a hydraulic profile dressing ~ev1ce for form dressing the grinding wheel. The main dress Ing sl1de, mounted over the grinding wheel, is equipped with p~eloaded and hardened roller tracks. Its movement is parallel w1th the gnnd mg wheel spindle. This slide carries a tracer slide mounted at an angle of 30 degrees on the 21 P machine and vertically on the 21 U machine, both move in hardened and preload ed ball tracks. The tracer slide contains the vertically mounted diamond feed barrel with the diamond holder in its lower end, the infeed mechanism and the follower. During the movement of the main slide the tracer slide follows the profile template and reproduces its form into th-e grinding wheel. The dressing cycle is automatic and changeover from rapid traverse to dressing feed is controlled by an interchangeable speed cam. The maximum dressing width covered by the standard dresser is 6". During the rapid return of the dresser slide the diamond and follower are automatically retract_ed from the grinding wheel and template. The dressing cycle 1s push-button operated and for stepless adjustment of the dressing speed, a knob is provided on th e dresser control panel. The 21 U profile dresser can be used for both straight and angular infeed grinding. For angular infeed grinding the angle on the profile cam must correspond with the infeed angle. The maximum profile depth is 1 1 h ". The 21 P profile dressing device is used for straight infeed grinding and due to its angular tracer slide, both diameters and faces can be dressed. The maximum profile depth covered by the standard dresser is 1". Profile templates and speed cams for specific grinding operations are quoted on request as extra equipment. Tracer slide movement Profile depth 1" -,- - ~-...rf~----- - =---_] Profile template Main slide movement 5
The conception of our basic design is such as to permit easy adaptation of further equipment for more automated operation of the machines. This is possible due to the special design of the infeed system, the hydraulic unit and the electrical equipment previously described under models 21 U-C and 21 P-C. AXIAL POSITIONING DEVICE When grinding with profiled grinding wheels it is, as a rule, essential that the parts are correctly located in relation to the grinding wheel. In order to compensate for variations in the depth of the centerholes and in the length of the parts, an axial position ing device must be used. This positioning device is fixed to the bed of the machine and its gauging finger can be set to contact the workpiece on the most suitable face. With this equipment, the position of the workpi ece is shown on a dial indicator and therefore precise axial positioning becomes a fast and easy matter for the operator to perform. The axial positioning device can be fully automated to provide correct location of the components without intervention of the operator. The automatic positioning device can be equipped with an automatic table clamp which locks the table when the workpiece is correctly positioned... ~I [t=j< Q y SPARK INDICATOR This unit consists of a photo-electric cell and an amplifier. The photo-electric cell is mounted in such a way as to register the sparks generated by the grinding wheel contacting the work'piece. Machines equipped with this unit are provided with an adjustable fast feed engaged from the end position of the rapid advance until the wheel contacts the workpiece. If the grinding allowance on the parts cannot be held fairly constant, an important time 'saving is obtained with this equipment. EFFECT RELAY A highly sensitive electrical relay device, capable of measuring and racting to minute amperage variations of the wheelhead spindle meter, can be supplied instead of spark-indicator. Th is device is adjustable for varying load conditions when grinding ferrous or nonferrous materials and justifies itself for variations of the free running amperage. When the grinding wheel contacts the workpiece the relay automatically and instantaneously switches from a fast to a normal rate of feed. This device is designed with a second or back-up safety circuit. 6
Numerous auxiliary functions synchronized with the other machine movements can be obtained. Manual operations can be reduced to loading and unloading of the workpieces. A grinding cycle of an automated machine equipped with Gauge Head, Spark Indicator and Axial Positioning Device will operates as follows: AUTOMATIC DRESSER CONTROL The profile dresser previously described under model D can be equipped with an automatic control unit. The required number of workpieces to be ground between dressings can be preset on a counter unit, which automatically starts the dresser when the correct number of parts have been completed. The number of diamond passes required per dressing operation can also be preset and the diamond feed is automatic. AUTOMATIC COMPENSATION As the grinding wheel diameter decreases due to repeated dressing, the infeed becomes longer and compensation must be made by advancing the wtieelhead with the infeed handwheel. This compensation can be carried out automatically by a compensating unit, which receives an impulse every time the wheel is dressed and advances the wheelhead by an amount equal to the diamond feed. 7
ces. A d Technical data 21 u 21 p ~ : I CAPACITY Center distance = max. grinding length.......... inch Swing......................... inch Max. grinding diameter with new wheel............. inch Min: grinding diameter with worn wheel... inch Max. workpiece weight between centers.................... lbs Max. workpiece weight in steadies......................... lbs Max. table swivel.................................. degrees 120-160 18-22 18-22 5 800 3000 4-3 120-160 18-22 18-22 3 800 ' 3000 4-3 WHEELHEAD Wheelhead slide swivelling clock-wise/counter clock-wise..._.................................. degrees Max. grinding wheel with standard wheelguard............ inch Max. width of multiple wheel set-up...................... inch Wheelhead motor, standard.............................. HP max........................ HP 45/90 24X3 X 12 8 10 25 30 X6X12 83/. 15 25 IN FEED Rapid traverse, as requested............................ inch 2 or 3 Max. grinding allowance for plunge or traverse grinding inch/dia.110 lnfeed steps for traverse grinding, infinitely variable.... inch/dia.00012-.004 lnfeed rate for plunge grinding, infinitely variable... inch/sec.00004-.012 Manual infeed length.................................. inch 5 Manual inching feed.................................... inch.0001 3.110.00012-.004.00004-.012 10.0001 WORKHEAD Swivelling................................... degrees Work center.......................................... No Spindle hole.......................................... inch Speed range, infinitely variable.......................... RPM Drive motor.......................................... HP 360 5 MTc' 1 1 h J 30-330 2 TAILSTOCK Work center.......................................... No Barrel retraction........................................ inch 5 MT 2 5 MT 2 TABLE MOVEMENT. Tabel speed, hydraulic, infinitely variable............ inch/min Min. hydraulic table movement......................... inch Reversing accuracy..................................... inch Dwell at one or both reversing points.................... sec Manual table drive................................ inch/rev 0-235.080.0004 0-8.417 0-235.080.0004 0-8.417 WEIGHT Weight of machine basic model. Excl. equipment and water tank. Grinding length 120 inch...................... approx. lbs Grinding length 160 inch....... approx. lbs Weight of standard equipment and water tank..... approx. lbs 24,200 27,500 900 25,400 28,800 900 DELIVERY,, By sea shipment th!3 machines are preferably delivered in container wh!*l possible. By land., transport delivery by car direct from manufacturer to customer is usually to prefer. Other f transport ways can of course be used. Since our machines are subject to constant improvements, specifications and illustrations _ shown in this catalogue can be changed without notice.
.,.. EZJEZJ A-A INFEED MECHANISM An important design feature of JOHANSSON Cylindrical Grinding Machines is the infeed mechanism of the wheelhead. The infeed mechanism permits fast manual grinding operations to very close tolerances without any additional equ!pment. It is also the basic system for a highly automated machme. The infeed mechanism is divided into three different systems, each operating separately from the others. The t~re~ systems are handfeed, hydraulic rapid advance and hydraulic mfeed. The manual feed is actuated from a hand-wheel at the front of the machine and drives a feed screw which is built into the wheelhead slide. The handwheel rotation is transmitted to the feed screw nut, which moves the wheelhead forward or backwards. actuates a ballscrew, wh ich in turn transmits the feed motion to the wheelhead directly and without intermediate parts. Machines equipped with an automatic grinding cycle and automatic gauge sizing will have an additional hydraulic control unit operating with two solenoid valves. The first solenoid valve is for switching the feed cycle from coarse to fine feed and the second solenoid valve stops the feed and retracts the wheelhead in rapid feed automatically. Both the coarse feed and the fine feed are individually adjustable as far as stroke and speeds are concerned. The hydraulic rapid advance is performed by a hydraulic cylinder with the piston fastened to the feed screw and the cylinder to the upper part of the wheelhead slide. The cylinder has a constant stroke and it is not influenced by the handfeed or the hydraulic feed. The hydraulic feed (grinding feed) is performed by a s~parate hydraulic cylinder, built directly into the wheelhead slide and with the stroke to be preset according to the actual stock removal of the workpiece. The setting is obtained by moving the back end stop for the piston stroke and the forward end stop is fixed and it can theref~>re be us~d as ~ positive ~top, when grinding without automatic measunng dev1ce. The p1ston 1 ' -.. ' '!
IE THE HYDRAULIC SYSTEM of the machine is supplied by a variable delivery type pump, which insures a minimum of heat generation. The hydraulic valves are of our own well proven design and they are grouped in two valve blocks, one each for the table and wheelhead controls. The pump as well as the filter, pressure gauge, and oil tank form a compact isolated unit outside the machine. THE LUBRICATING SYSTEM is equipped with a central multi-piston pump for the lubrication of all slideways. In order to obtain an even flow of oil to all lubricating points, each one is supplied by its own separate feed piston. THE TABLE is hydraulically operated, its speed is infinitely variable and reversing accuracy is.0004". Table dwell infinitely variable from 0-8 sec. can be selected at the right or at both table reversing points. The swivel table is equipped with a graduated scale and a dial indicator attachment for accurate angular adjustment. THE WHEELHEAD INFEED is composed of 3 independent movements, which are manual feed, hydraulic rapid approach, and hydraulic infeed. The max. stock allowance on diameter is.110". The hydraulic infeed can also be used as a pickfeed when traverse grinding. The increments are infinitely variable from.00012"-.004". THE ELECTRICAL EQUIPMENT is located in a separate cabinet, in which all switch gears are easily accessible. All electric motors have double protection. The complete electrical installation is connected to the power line through a main switch used for disconnecting the machine. THE COOLANT SYSTEM is, in its standard version, composed of a separate 56 gallon tank mounted on rollers. For clarifying the coolant, the tank is provided with a number of baffle plates and settling compartments. The coolant nozzle is adapted to the width of the grinding wheel, other nozzles can be supplied on request.