Operation Manual For Valve Repairing Grinder VRM-PM800B

VRM-PM800 VALVE REPAIRING GRINDER (Version 1.0)

RETOP Valve Repair Co., Ltd.June 2014

RETOP VALVE REPAIR CO., LTD. Zigong Sichuan, China T 86-813-2208857 WITEAM COMMERCIAL [email protected] www.re-top.net " 1

OPERATION MANUAL

Patented Product, Counterfeiting Not Allowed!

FOREWORD

You are welcome to buy valve repairing grinders from us and become our customer. In this manual, operation instructions to the VRM-PM800B Model Valve Repairing Grinder shall be provided. Valve repairing grinder is specially designed for repairing of various valves, and it is developed based on the principle of dynamic balance. Its main function is grinding after build-up welding for the damaged valve parts. The grinder will be driven by variable frequency motor. It features with infinitely variable speeds, constant power, constant torque, planetary grinding head, as well as coordination of revolution and rotation, thus, strong grinding capability can be provided to make the grinding surface up to mirror finish level. VRM-PM800B Model Valve Repairing Grinder is the second generation product, improved from the VRM-PM800 model valve repairing grinder. The grinder had obtained the National Invention Patent of China; it is not only beyond the conventional valve repairing modes through universal machine tools, but also different to the mechanical equipment for valve manufacturing, the chucking tools and the process flow. The grinder is one kind of special equipment to grind the build-up welding section on valve sealing faces, which uses stainless steel and cemented carbide welding materials.


Contents

1 Features and Performance Parameters of the Grinder 4 1.1 Grinder Features 4

2 Installation of Wedge block Components 5 2.1 Introduction to the Wedge block Components 6 2.2 Installation of Wedge blocks 6 2.3 The Function and Installation of the Guiding Plate 6 2.4 The Usage of the Guiding Ruler 7

3. Build-up Welding of the Sealing Surface 8 4 Installation of Grinding Disc Extension Rod 9 5 Installation and Connection of Grinding Disc 10 6 Elevation Height Adjusting 11

7 Selection of Hoisting Assembly 12 7.1 Motorized and Manual Forklift 12 7.2 Fixed Hoisting Assembly 12 7.3 Traveling Block 12 7.4 Placement of Valve on the Repairing Table 12

8 Installation of Grinding Disc 14 9 Regulation of Grinding Precision 15

10 Grinding Procedures 16 10.1 Feeding for Preliminary Test (Grinding Wheel) 16 10.2 Power-on for Grinding 16

11 Grinding Materials and Grinding Wheels 17 11.1 Selection of Grinding Materials 17 11.2 Selection of Opening, Specification and Hardness 17

12 Cooling of Work Pieces 18 12.1 Formula of Cooling Fluid (for reference only) 18 12.2 Type of Cooling 18

13 Wedge Disc Manufacturing and Assembly 19 14 Electrical Installation 20

14.1 Overview 20 14.2 Electric Circuit Diagram 20

15 Matters Need Attention 21


1 Features and Performance Parameters of the Grinder 1.1 Grinder Features VRM-PM800B Model Valve Repairing Grinder is a special machine tool for valve repairing, which is designed, developed and manufactured by RETOP Valve Repair Co., Ltd. and obtained the National Innovation Patent of China. VRM-PM800B is improved from the first generation product VRM-PM800 model grinder; the new model has a good performance and its various performance indicators reached international level. In addition to its high price performance ratio, it owns some innovative functions that other similar products do not have; it is a good alternative to other valve repairing products. VRM-PM800B has a compact and reasonable overall layout, and its high rotation speed, high precision and high rigidity could provide high efficiency and reliability for user’s operation.

The grinder is mainly consists of two columns and a repairing table. The repairing table is made of high-tensile steel, which could greatly improve the bending resistance, torsional rigidity performance of the grinder during its operation; meanwhile, the stability of the grinder could be enhanced by making two times of ageing treatment to the repairing table. The highly rigid and highly stable repairing table provides a strong guarantee for the high precision operation of the overall grinder.

The grinder is equipped with an independent spindle unit which is configured with high-precision special bearing. Special purpose bearing grease shall be applied to lubricate the bearing. The entire spindle unit has little thermal deformation, good thermal stability and good precision retaining ability and it is maintenance free. Meanwhile, the entire spindle unit has a good rigidity and an ideal mounting and dismounting performance. The spindle is driven through high power AC variable frequency motor, therefore, the spindle unit could perform rough grinding and fine grinding to the valve sealing surfaces in an high-precision, high-rigidity, high rotation speed and efficient manner.

The grinder is provided with column sleeves which are driven by the electric motor to save both time and labor; meanwhile, the column sleeves are provided with limiting devices to avoid faulty operation and provide safety assurance for users in operation.

As the feeding system of the grinder is completely driven by the variable frequency motor through direct connection, it has a good rigidity, dynamic performance and it has no noise. Because one rotation (360°) of the hand wheel represents 0.1mm feed in the feeding system, the operating precision is improved greatly to make the grinder realizing precision movement and positioning. High-duty grinding could be made to the sealing surfaces after build-up welding or spraying with stainless steel or cement carbide materials to reach a roughness of 0.8; high speed precision grinding could be made to the sealing surface only by replacing the wheelhead and adjusting the rotary speed, reaching a curvature tolerance of 100%, radial curvature tolerance of 100% and a surface roughness of 0.6.



Main Technical Specifications and Parameters (Unit: mm)

Dual ColumnsH OD WT

2265 188 25

Column SleeveL OD ID

300 240 188

Beam L 530 W 240 H 300

Beam Enclosure L 330 W 340 H 360

Repairing TableL W Face Plate Thickness 50

1400 1200 Machine Leg Height 200

Combined Wedge BlockL W For valve body &

wedge disc processing900 90

Grinding Disc Extension Rod

L OD Structure Morse taper grade 4450, 600 70 – 75 Taper and Flange Type

Main Transmission SpindleL OD Rotary Speed

668 50 – 90 0–3000 r/min

Spindle SleeveL OD Travel

414 150 60

Center DistanceColumn to Spindle Center Repairing Range Plain Grinding Precision Sealing Surface

of the Valve Body to Be Grinded700 DN200 – DN800 0.01mm-0.03mm

Grinding Disc SpecificationDN200–DN250 DN300–DN350 DN400–DN450 DN500–DN550

DN600–DN650 DN700 DN750 DN800

Pain Grinding Tool, Chamfer Grinding Tools,

Grinding Wheel Rack

DN200–350 DN400–800

L 60, W42, TK 20 L 70, W 45, TK 23

Grinding WheelDN200–350 DN400–800

BW50×25×13A46LB35 BW75×32×20A46LB35

Hand Feed Wheel For feeding and retracting, one rotation of the hand wheel (360°) represents a feed of 0.1mm

Stopper Used to control the elevation range and spindle locker, so as to ensure personnel and equipment safety

Spindle Locker Used to replace the grinding disc extension rod, grinding disc and grinding wheel rack when the spindle is in stationary state

Wire Control Switch Manual wire control to facilitate the grinding operation and the replacement and fine adjustment of the grinding disc, grinding wheel, and grinding disc extension rod

Speed Regulator Used to control rotation of the grinder spindle, so as to regulate the grinding speed

Speed Motor Variable frequency motor model: YVP112M-50-A, motor power 4KW, 380V

Frequency Converter Model: HD30-4T5P5G/7P5P

Elevation Motor Model: Y90S-4, motor power 1.5KW, 380V

Elevation Mode Gear reduction, elevation speed 1120mm/min

Elevation Range Elevation range 1400mm, operating height 1300mm

Operating Height 2300mm

2 Installation of Wedge block Components

2.1 Introduction to the Wedge block Components There are 24 threaded holes on the repairing table to install two pieces of 5° wedge blocks (Fig. 2-1) which their installation positions can be adjusted by setting different hole spacing to repair and machine valves with various sizes (DN200-DN800) on the repairing table. The wedge blocks are used to bring the original slant sealing surface to a horizontal plane to facilitate machining operation. There are two very important accessories supporting the use of wedge blocks, i.e. guiding ruler and guiding plate, both of which determines the fitness accuracy and the percent of contact area when the grinded and machined valve sealing surface and the wedge disc are assembled and guarantee zero leakage of the machined valves.

2.2 Installation of Wedge blocks As each wedge block has two ends (i.e. larger end and smaller end) that the larger end is thicker and the smaller end is thinner, wedge blocks should be installed properly as specified below. Firstly, determine the appropriate threaded hole spacing on the repairing table to install the valve to be repaired based on its size, then, place the smaller ends of the two wedge blocks towards the columns and align them to the mounting holes of the repairing table and fasten them slightly with 4 nos of M16 hexagon socket head cap screws, and then measure, adjust the opening sizes of the two wedge blocks before tightening them up. Please note: the opening sizes of the two larger ends and that between the two smaller ends of the two wedge blocks must be equal.

2.3 The Function and Installation of the Guiding Plate Machining operation is not allowed if the valve body is placed on the wedge block randomly, or otherwise, there would be certain angle between the grinded sealing surface and the wedge disc when assembling them, which will further lead to sealing failure. The guiding plate is a device to avoid such angles. It is one piece of rectangle steel plate after fine grinding; and it is a carrier tool of the wedge


Fig. 2-1 Structure of Wedge Block

block and will be used together with the guiding ruler. The operating spacing of two wedge blocks is determined based on the valve size: the operating spacing of the wedge blocks should be appropriately increased along with increase of the valve sizes; however, the boss and the concaved shoulder of the double flanges should be placed on the two wedge blocks. It is very easy to install the wedge blocks: as there are threaded holes on the larger end of the wedge block, firstly install the wedge block and then fix the guiding plate; that is OK.

2.4 The Usage of the Guiding Ruler The guiding ruler is arc-shaped and the widths of both ends are equal, and the horizons of both ends are same. It will be used together with the guiding plate to adjust the depth of parallelism between the valve’s sealing surface and the wedge block and thus to control and/or eliminate the angle between them. You must be careful to make such adjustment accurately.


3. Build-up Welding of the Sealing Surface The efficiency of valve sealing surface grinding operation largely depends on the quality of build-up welding, and higher quality of build-up welding of the sealing surface represents higher grinding efficiency. Main factors guaranteeing good build-up welding quality are as below:

1) Polish and flush the scale layers on the sealing ring (or surface) with abrasive cloth, clear water or grind off the parts severely corroded with the polishing machine before welding so as to avoid pores on the surface to be grinded after build-up welding.

2) Spot welding or repair welding to the sealing surface are not allowed when conducting deep level repairs to the old valves, and 360° full circle build-up welding must be made so as to generate a new sealing surface and prolong the service life of the valves.

3) The welding beads on the sealing surface conducted build-up welding should be even and with same width, and the surface of the welding beads should be smooth. The height of the build-up welding layer on the valve’s sealing surface is generally 3-4mm, and its width should be 2-3mm greater than that of the sealing surface of the old valves; the widths of stop valve’s valve flap and the gate valve’s wedge disc after build-up welding treatment should be greater than 3mm. Hemming (360°) build-up welding to the wedge disc and the flap must be made and repair welding must be mad to the pits, gaps appeared after turning or grinding processes, so as to guarantee their roundness and assembling width (actual size). The thickness of the build-up welding layer of the wedge disc should be determined by the opening parameters of the sealing surface of the valve body, which refers to the distance between the left and right sealing surfaces (sealing rings) of the valve body. There are still bigger end (valve port side of the middle flange) and smaller end (bottom section of the valve cavity). Before build-up welding of the wedge disc, it should accurately measure the distance between the two ends of the sealing surface and determine the thickness of build-up welding layer based on the measured parameters, which should be no less than 2.5mm so as to guarantee enough allowance for machining.


4 Installation of Grinding Disc Extension Rod The lengths of the valve body are different for different sized (DN) valves. The operating height for grinding process refers to the vertical length of the valve body placed on the wedge blocks. The extension rods are the connecting link between the main transmission spindle and the grinding disc; the lengths of the two kinds of extension rods are different, and their structures are also slightly different. It will be determined by the valve conditions that which kind of extension rods should be used, i.e. use the flange type extension rod (650mm) for large valves (DN400-DN800), taper type extension rod (450mm) for small valves (DN200-DN350). Both ends of the flange type extension rod are provided with flange plates; the mortise joint will be connected with the tenon joint of the transmission spindle’s flange plate through threaded connection, while the tenon joint will be connected with the mortise joint of the grinding disc through threaded connection. Do not damage the mortise & tenon joints when making connections.


5 Installation and Connection of Grinding Disc Re-Top Valve Repairing Grinder could repair a wide range of valves with various specifications, which covers 13 kinds of specifications from DN200 to DN800, and we also customized 12 pieces of grinding discs specifically for valve repairing. Taper type extension rod should be connected to the grinding discs for DN200-DN350 valves; as there are threaded holes on the external taper end, the taper type extension rod should be tightened by M14 bolts and nuts. Flange type extension rod should be connected to the flange type grinding discs for DN400-DN800 valves.


6 Elevation Height Adjusting As the grinding disc suitable for DN200-DN350 valves is installed on the extension rod in advance, the grinding disc cannot reach the valve chamber if the height of the location of the grinding disc is lower than the height of the valve; therefore, it must adjust the height of the main set to operate properly. The adjusting procedures are: switch on the power and operate the hand controller to elevate the main set 150-250mm above the valve, then, place the valve on to the wedge blocks. For DN400-DN800 valves, it may first place the grinding disc and the extension rod into the valve chamber if it is impossible to move the grinding disc in the valve chamber when the main set is elevated to its height limit, then, lift the valve and place it on to the wedge blocks and make the connection between the extension rod and the flange plate of the transmission spindle and the connection between the extension rod and the grinding disc; as the extension rod and large grinding disc are heavy, auxiliary tools and equipment are required for the connection.


7 Selection of Hoisting Assembly

Hoisting assembly is essential for this grinder to repair valves, and the selection of proper type of hoisting assembly relates to the progress and efficiency of valve repairing, as well as safety in production. Therefore, it should be treated seriously and there are three types of hoisting assemblies selectable:

7.1 Motorized and Manual Forklift Firstly, motorized forklift is preferred for wider sites and spacious environments, which is featured with high power, flexible movements, stable operation, large loading capacity, higher hoisting height and is suitable in particular for the repairing, hoisting and handling of large size valves with a weight over 3 tons. Then, 3-ton manual forklift can be used for a loose repairing environment. All in all, forklift is a necessity for valve repairing operations.

7.2 Fixed Hoisting Assembly Fixed hoisting assembly is one kind of stationary hoisting assembly designed specially for hoisting of valves to be grinded and machined, which will be installed by the side of the grinder and cannot be used to handle valves like the forklift. As the large size valves are large and heavy, and the weight of DN400-DN800 valves can reach 1-2 tons, and the weight of high pressure valves above PN6.4 (MPa) is even higher, hence the load capacity of the hoisting assembly should be designed above 3 tons. In order to facilitate valve handling, grinding of both sides of the sealing surface, the fixed hoisting assembly should be capable of rotating by 360°. Although both chain blocks and electric blocks can be used, we recommend it is better to use electric blocks if the height of the workshop is enough. From a point of view of professional valve repairing, fixed hoisting assembly is ideal.

7.3 Traveling Block Traveling block has a large lifting capacity and wide operational range, and it can move freely horizontally and longitudinally. However, it is not specific and fixed for professional valve repairing, and it has a low efficiency on adjusting the inclination of valves under repair. The reason is that the travelling block is shared by all workers in the same workshop and the possibility in waiting is inevitable, which will affect the valve repairing progress and work efficiency. Furthermore, traveling block should be installed at a higher place and it is liable to cause swing during hoisting operation due to the longer wire cables, which would easily lead to friction between valve body and grinder body and hinder the positioning of the valves to be repaired.

7.4 Placement of Valve on the Repairing Table Erect the valve and hold the double flange end down and the other end up. Place the valve onto the wedge block with the hoisting assembly (keep the middle flange in same direction with the big end of the wedge block). Conduct preliminary adjustment for center-to-center and line-to-line alignment, i.e. align the flow orifice of the valve to the center of the grinding disc and slightly lower the grinding disc till it is enough to install the grinding disc. However, you should carefully observe the descent height of the grinding disc to avoid deformation or damage to the grinding disc due to the impact with the seal ring. As the valve body is inclined for some degree on the wedge block and there is certain angle between it and the grinder’s spindle, hence, the grinding disc cannot be put into the valve chamber in on try, or


otherwise it will collide with the valve wall. Therefore, it should handle and adjust the valve body for two time before get it in a proper location.


8 Installation of Grinding Disc Install the grinding head when the grinding disc and the valve orifice preliminarily aligned center to center, meanwhile, adjust the position of valve body so as to preliminarily adjust the grinding surface of the build-up welding layer of the valve.

The steps are as below:

1) Firstly install a grinding head on the grinding disc at a position enough to cover the build-up welding surface by the grinding wheel. After installing the grinding head, manually rotate the grinding disc slowly for one turn around the sealing ring and carefully check whether the grinding head covered the entire grinding ring. It must be correctly adjust the width covered by the grinding head on the grinding disc and properly record the positioning parameter well-tuned (screw fixation location).

2) Install the second and third grinding heads as per the parameters set for the first one. When repairing large size valves, it can use six ∅50×25×13 grinding wheels or 3 ∅75×32×20 grinding wheels.

3) Collision or friction between the extension block where grinding wheels to be installed and the valve guide rib are strictly forbidden and avoided, and a least 5mm interval should be provided. Friction between the upper end of the extension block and the sealing surface at the upper section of the valve body is not allowed, so as to ensure the smooth operation of the grinding head. Screws to secure the extension block must be tightened to avoid flyout when the grinding head runs in high velocity.

4) The installation method of the chamfering grinding head is same to that of plane grinding head, but you need to align it with prudence to ensure the internal and external roundness of the sealing ring after chamfering operation.


9 Regulation of Grinding Precision Grinding precision refers to the sealing precision in general for assembling of the grinded valve sealing surface and the wedge disc after machining out the plane by placing it on the wedge block. The center line of the valve sealing surface and the center line of the wedge block must be coincident to make the precision of the wedge disc and valve sealing surface up to standard to meet the requirements of zero leakage sealing performance, or otherwise, there would be angles or broken line on the seal belt. In short, valves placed on the wedge block must be aligned center to center and line to line, no deviation and offset is allowed. Method to control the precision: firstly hold the lower end of the guiding ruler close to the guiding plate and take it as the basic reference and hold the upper end of the guiding ruler on close to the plane covering the two screw holes at the bottom of the middle flange, then, adjustment should be made if there is clearance at the left or right side, which indicates the valve is not aligned properly on the wedge block. Specifically, you should hammer the backside of the middle flange with clearance or use other means to hold it close to the middle flange and eliminate the clearance, make it match perfectly. When everything is done, fix the valve on the wedge block with the bolted pressing plate.


10 Grinding Procedures Velocity + grinding wheels are the key elements for the grinding function, and the amount of feed of grinding operation is much smaller than that of turning operation. Grinding operations for the work pieces made by common type grinding machines are based on turning, milling operations, which are to increase the precision of the work pieces, while the grinding operations made by Re-Top’s valve repairing grinder are for the valve sealing surface with stainless or cement carbide build-up welding layers, totally by grinding and no extra processing from preliminary grinding to fine grinding. It is where our grinder is uniquely different to other brands. The design philosophy, structure, grinding functions and operations of the grinder differs to others.

The operation method of this grinder is as below:

10.1 Feeding for Preliminary Test (Grinding Wheel) Unprocessed build-up welding surface is uneven, and the salient points on it will be grinded off one by one through intermittent grinding operation. As big impact force to the grinding wheel will be generated if feeding too fast during preliminary grinding period and then cause damages and cracks to the grinding wheel easily, hence, trying of the appropriate amount of feeding step by step is necessary. The specific practices are: rotate the hand wheel on the grinder body with right hand in counter-clockwise direction (indicated by the arrow), meanwhile, rotate the spindle flange plate or grinding disc extension rod with left hand, so as to learn and get hold of the contacting conditions of the work pieces. The grinding wheel would contact the grinding surface if heard slight swishing sound in the valve chamber, then, you can stop rotating the hand wheel and retract to wait for power-on.

10.2 Power-on for Grinding Power on the grinder, lock the columns, and regulate the speed governor (potentiometer). Feed steadily with constant velocity when the revolution of the spindle reached 1000/Min, and increase the velocity gradually along with the velocity consumption of the grinding wheel, and then you can feed with constant velocity when it reaches 1200/Min-1500/Min. You can retract and power off the grinder when the sealing surface is bright and smooth, and the weld marks disappeared and it width reached a proper level. Next, replace the grinding head with a chamfering grinding head to conduct internal and external chamfering grinding and change into the previous grinding head to conduct positioned grinding with constant velocity when chamfering grinding is completed. Conduct fine grinding with constant grinding until the completely disappear of friction sound as a result of grinding operation when the handle rotated below the hand wheel and stopped rotation.


11 Grinding Materials and Grinding Wheels 11.1 Selection of Grinding Materials There are so many of welding materials for the valve sealing ring, such as stainless steel, cement carbide, cobalt-based, tungsten carbide etc., which has different functions with respect to their acid resistance, alkali resistance, heat resistance, corrosion resistance and wear resistance, and different hardness. Thus, it is necessary to select appropriate grinding materials specific to the properties and hardness of the welding materials, for example, monocrystalline fused alumina, fused alumina zirconia and pink fused alumina grinding wheels can be selected for 304, 316 stainless steel. For another example, green silicon carbide grinding wheel should be used for cobalt-based and tungsten carbide welding materials with a hardness over HRC50. The grain size of the grinding materials for the grinding wheels should be 46#.

11.2 Selection of Opening, Specification and Hardness 1) Flaring cup grinding wheels are suitable for plane grinding, particularly for intermittent grinding of uneven work pieces;

2) Small size grinding wheels are suitable for valves with a smaller cavity and their specifications are BW50×25×13 and BW75×32×20, and the specification for chamfering plat grinding wheel is BW100×60×20.

3) Medium soft grinding wheels, marked as L, should be used for welding materials with hardness over HRC50, and soft grinding wheels, marked as K, should be used for welding materials with hardness over HRC50.


12 Cooling of Work Pieces Grinding heat, reflected by the grinding temperature, will be generated in the process of grinding due to internal friction of the sealing weld materials and external friction of the grinding wheel. Grinding heat is not obvious during intermittent grinding operations and the grinding temperature is not too high; however, the width of the sealing face get more and more clear along with the gradual grind-off of the salient points on the build-up welding layers of the sealing ring, and then the grinding temperature will increase accordingly. Particularly, the temperature at the grinding area will usually reach 1000℃ – 1500℃ when intermittent grinding finished and the build-up welding layer flatted, therefore, sufficient cooling must be made.

The function of the cooling fluid is to flush the abrasive dust and abrasive grains to avoid scratches to the grinding surface or blocking of grinding wheels. The cooling fluid also has lubrication effect, which could reduce the friction between the abrasive grains and the surface of the work pieces and improve the surface smoothness of the work pieces.

12.1 Formula of Cooling Fluid (for reference only)

12.2 Type of Cooling 1) Water tank + water suction pump, cooling with circulation water.

2) Provide intermittent artificial cooling with water stored in plastic bottle (cooling fluid prepared).

Soda (soda ash) 1%

Sodium Nitrite 0.25 — 0.5%

Water 98.75 — 98.5%


13 Wedge Disc Manufacturing and Assembly Before turning the wedge discs after build-up welding or spray welding, it should first measure the precise opening size of the big end and small end of the sealing ring of the valve body, in another word, it should preliminarily get the thickness of the big end and small end of the wedge disc and provide a sound basis and reliable parameters.

The methods are as below: 1) Apply build-up welding on one side of the wedge disc and machine out the plane through turning machine with special tools, then, apply build-up welding to the other side and precede the turning process. It should be noted that internal and external full circle build-up welding and repair welding for surface layer should be made to the wedge disc to avoid welding notches or sags.

2) Repeat the turning process for several times coordinating with the valve sealing surface machining process when turning the wedge disc, i.e. adjust and correct its position on the wedge block with the dial gage based on the squeezing mark on the sealing belt of the wedge disc, so as to align with the center of the circle and realize the alignment as shown in Fig. 13-1 and then to eliminate the included angle and guarantee the goodness of fit and contacts between the valve sealing surface and the wedge disc.

3) Fine grinding should also be made to the wedge disc with special grinding tools without removing the repairing clamping fixture when turning of the wedge disc is completed, or alternatively to unload it to conduct lapping.

4) Put the wedge disc into the valve chamber to seal and assembly it and conduct preliminary seal test with city water; and overall valve assembly can be made when there is no overflow of water drops and no moistures.


Fig. 13-1 Alignment of Valve Body and Wedge Disc

14 Electrical Installation

14.1 Overview The power input, power output, rpm display, speed regulation and overload protection, safety protection of the driving shaft motor are controlled by the frequency converter, and only power indicator, power switch, potentiometer, air switch, AC contactor, leakage protection switch are installed on the outside panel.

14.2 Electric Circuit Diagram


15 Matters Need Attention

■ As there is certain angle between the vertical grinding disc extension rod and the valve body slightly inclined on the gradient block and the space between the grinding disc and valve channel is small, it requires handling the valve body for several times to adjust the grinding disc to put it into the valve chamber. In this process, collision or friction between the grinding disc and valve wall are not allowed, or otherwise the precision of the grinder will be affected.

■ Operator should not face the middle flange of the valve during grinding operation to avoid injury as a result of broken grinding wheels.

■ Although the transmission shaft lock could facilitate the installation of the grinding disc and grinding head while the grinder is not running, its use while the grinder is in operation is forbidden.

■ Collision between valve body and the grinder body or flange plate on the transmission shaft are not allowed, regardless which kind of hoisting assembly is used, when installing the valve on the repairing table.

■ Extension block for the grinding head should be placed on the groove for grinding disc and retaining screws should be tightened to avoid personal injury due to flyout of grinding head during operation.

■ Dusts, sands and coolants on the repairing table, columns, gradient blocks and grinding head should be cleaned and maintained with machine oil before going off duty.


Patented Product, Counterfeiting Not Allowed!

Devices & Hardware

Operation Manual For Valve Repairing Grinder VRM-PM800B