The essence of the invention: the grinding tool is placed on the largest diameter of the part in such a way that the plane of its rotation is parallel to its diametral plane. The tool is moved along the generatrix of the motion condition of the plane of its rotation along the diameter perpendicular to it, and the axis of rotation - normal to the specified diameter. After the tool reaches the center of the product, the direction of rotation of the tool and the movement of the rotation axis are changed to the opposite. In this case, the angle p between the direction of feed along the generatrix and the plane of rotation of the tool is chosen according to the given formula. 1 salary, 4 ill.
UNION OF SOVIET
SOCIALIST
REPUBLIC- ((9) ((() (i)z V 24 V 5/16
STATE PATENT
USSR DEPARTMENT (USSR STATE PATENT) /
(21) 4876246/08 (22) 07.25.90 (46) 15;12.92. Bull. M 46 (71) All-Union Scientific Research and Design and Technological Institute of Chemical Engineering (72) E.I0. Feldman and R.N. Friedman (56) Copyright certificate of the USSR " " " No. 1399085, class B 24 B 19/02, 1986.
M 742111, class. V 24 V 5/16, 1975. (54) METHOD FOR GRINDING CONCAVES
CURVED SURFACES (57) The essence of the invention: the grinding tool is placed on the greatest
2 the diameter of the part in this way. that the plane of its rotation is parallel to its diametrical plane.. The tool is moved along the generatrix from the condition of movement of the plane of its rotation along the diameter perpendicular to it, and the axis of rotation is normal to the specified diameter.
After the tool reaches the center of the product, the direction of rotation of the tool and the movement of the rotation axis are changed to the opposite. When the angle (P) between the direction of feed along the generatrix and the plane of rotation of the tool is chosen according to the given formula. 1 z.p.f-ly, 4 il.
The invention relates to abrasive processing of large curved surfaces, for example elliptical bottoms, cones, used in various agricultural sectors.
Currently, large-sized curved bodies of revolution. mentioned above are sanded using a copyless stitching method. When grinding in this way, the abrasive tool cogs the shaped profile of the product without special tracking systems and copying devices, while the wheel is moved in the plane of its rotation along the forming part, with a certain feed per revolution of the product (stitch feed). Copying a curved profile occurs through a combination of vertical and horizontal forced movement of the grinding head and rotation of the latter on the suspension axis; . This method is widely known t1), However, the abrasive tool is moved along the generatrix of the shaped profile of the product along two coordinates - either with a perpendicular direction to the velocity vector of the part and the tool, or with a collinear one (i.e., processing is carried out by part of the end or periphery of the cutting surface of the tool).
Since the abrasive wheel does not have a continuous cutting edge, marks of varying depths, parallel to each other and to the forming parts, will be applied to the surface being processed. During subsequent passes with constant technological conditions, part of the abrasive grains will fall into already cut grooves, therefore, the efficiency of the process is reduced. and to remove a given allowance it is necessary to make additional passes. This leads to an unjustifiably increased consumption of abrasive material.
Re-adjustment of technological modes for each pass increases machine processing time.
As a prototype, a method is adopted, the essence of which boils down to the following; an abrasive tool mounted on a hinged grinding head is pressed against the workpiece, keeping the angle of inclination to the vertical constant, equal to 45°, and the grinding head is moved in the plane of rotation of the tool, along a curved generatrix from line to line from the center to the periphery (or vice versa) bodies of rotation, reversing the tool.
The grinding head moves only in the plane of rotation of the tool, and the ratio of these components is kept equal
Sx/Sy = t9 f °
It is known that BC = 2 /Y, = B2 + 4 dt, VD =
50 where B is the height of the tool;
d – tool diameter:
t is the grinding depth.
Consequently, the line width will increase by
The optimal angle p will be equal to. coinciding with the plane of the generatrix along which the tool moves.
This method provides mechanized grinding of large bottoms, 5 But in roughing operations this process is quite labor-intensive.
The purpose of the invention is to increase the productivity and quality of grinding large curved
10 surfaces.
Figure 1 shows a diagram of the formation of a line when the plane of rotation of the tool is perpendicular to the direction of feed H, Fig. 2 shows a diagram of the formation of a line
15 when the feed direction is at an angle other than direct to the plane of rotation of the tool; Fig.3 shows a diagram of the movement of the tool along the generatrix of the bottom; Fig.4 is a side view, 20 When a line is formed with a feed direction perpendicular to the plane of rotation, the latter removes a layer of metal with a depth t, and the contact surface is a part of the cylindrical surface AB-SD (Fig.1). In this case, the width of the line is equal to the chord BC = AD. This cylindrical surface c. combination with the surface of the part gives a rectangle ABCD, in which AC = WD. If you rotate the abrasive tool at an angle so that the plane of its rotation with the direction of feed makes an angle p. 90О, then the cylindrical contact surface of the tool with the ABCD part will also unfold
35 per angle (Fig. 2) and the width of the line will be determined by the length of the diagonal VD of the rectangle ABCD. In this case, during processing, the feed per line is maintained as the sum of its components
Ags sew quality of the processed surface and p = ags c - -. reduce consumption of abrasive material.
At this angle of rotation, the diagonal is 8D. Figure 4 shows the feed pattern Sx Sy, perpendicular to the feed direction along Sz. the combination of which allows the abrasive line, and the width of the line is maximum. By allowing the tool to move along a given path, the number of lines on the specified (0-0-0 Fig. 3) trajectory decreases. product and machine time for processing. The formula of the invention leads to increased productivity. 1. Method of grinding concave curves process. linear surfaces at which they were grinding. Based on this, the internal grinding tool is rotated and large-sized curved ones are moved along the generatrix of surfaces, for example elliptical bottoms, of the part that is being rotated, but it is advisable to do it by alternating in that, in order to increase the tool movement along the O-generator, productivity and improve quality
About, located at an angle to the processing plane 15, the grinding tool rotates the tool, from the periphery, the days are placed on the largest diameter of the part towards the center, and after the tool exits in such a way that the plane of its rotation is parallel to the center of the product, the direction of feed and rotates - to its diametrical plane, the movement of the tool is changed to the opposite direction of the tool along the generatrix. 8 as a result, the risks 20 are carried out from the condition of movement and are flat formed when the tool passes its rotation along perpendicular to the ment along the generatrix 0-0 and the rotation of the product diameter to it, and the axis of rotation is normal to the angle a changes the angle to 90°, but the specified diameter, at the same time, according to Therefore, when the tool will work reaching the center of the product with the tool, along the forming 0-0 microrelief of the processed - 25 change the direction of rotation of the instrumented surface will represent a co-ment and movement of the axis of rotation on the opposite mesh in the form of a cross in the opposite direction . the location of the marks, which leads to an increase in - 2. The method according to claim 1, characterized by increased productivity and improvement in that the angle between the feed direction of the quality of the machined surface, as well as 30 along the generatrix and the plane of rotation, excluding the operation of editing the tool, is selected according to the conditions: ment and idle passes. - g, V. Sx
Using the example of a cam shaft, it becomes clear that in production conditions it is also necessary to process parts with curved surfaces. Unlike cylindrical grinding, in which the workpiece is processed to a perfectly cylindrical shape, when grinding curved surfaces, a given non-cylindrical shape is maintained, the surface of which is brought to the required quality during the grinding process.
Shaft-type parts include, for example, cam shafts, disc cams and pump shafts. Different production tasks place different demands on machine design. However, even for highly specialized machining tasks, such as the grinding of passenger car cam shafts, different machine concepts can be used to meet market requirements. Thus, for processing curved surfaces, it is impossible to do without machines of a modular concept and appropriate technology. The customer may require a machine with multiple grinding spindles for pre- and finish grinding, or a machine with two supports for simultaneous machining of the inner and outer diameters or for synchronous centerless grinding.
Grinding technology using CBN grinding wheels for grinding curved surfaces
The use of CBN is an advanced technology for grinding curved surfaces. In the future, cutting speed will be increased to improve machining productivity. To machine parts that have low grinding allowances and low dimensional stability, such as assembled cam shafts, it is necessary to develop grinding systems that transfer much less grinding forces to the part. Gradually tightening and changing market requirements will also drive innovation in the field of curved surface grinding in the future.
To meet the different requirements for grinding machines and machining processes, EMAG has developed a range of technology modules and machines that are optimally adapted to the respective production conditions (see below).
Application examples
A typical example of grinding curved surfaces is the machining of cam shafts. In a completed complex project with manual loading, for example, four double jaws can be ground. The most difficult technical task regarding grinding is rough machining with an allowance of up to 3 mm and finishing machining with only one grinding wheel. Opposite machining requirements can be met using a vitrified bonded CBN grinding wheel.
Another example is the complete machining of truck camshafts: twelve control cams, six pump drive cams, seven bearing journals, the main journal and the taper and shoulder ends are machined in one setup. Since internal stresses may arise when processing hardened shafts, and grinding the cams can lead to radial runout of the bearing journals, processing the part according to the drawing in one step is impossible. To achieve the required quality in the best possible way often processing in one installation.
Sanding wood by hand, although it requires more labor, in return provides a number of important advantages: less aggressive processing, better control over the process and high quality surface treatments in hard to reach places– in corners, on smooth curves and other reliefs of any complexity.
Manual technology is indispensable for interlayer sanding of finishing coatings, as it ensures the most delicate work and eliminates the risk of rubbing off the applied finish. When using the same abrasive, hand sanding guarantees a better quality surface than sanding with a sander, grinder or drill.
About grinding pads and making them yourself
Sanding blocks (grinding pads) are an indispensable assistant in a carpenter's arsenal. These simple devices ensure uniform contact of sandpaper with the surface being treated, increasing the speed and quality of the work performed. Using such pads, you will significantly improve the quality of grinding, extend the life of the abrasive, and avoid irreparable defects in the form of depressions and rounded ends.
To acquire such a grinding tool there is no need to spend extra money. It will not be difficult to make it yourself from dense foam or wooden scraps. Check out some easy sanding block projects in our gallery.
With this sanding block, which you can easily make from scraps of wood you have lying around, you won't have to waste time changing sandpaper. Wedge clamps are a simple and functional alternative to traditional clamps. A simple corner block will prevent accidental rounding of edges when sanding the ends. To sand smooth curves, use curved blocks made from scrap wood or foam. For grinding grooves or wooden products with a round cross-section, for example, balusters, use an additional soft backing. Don’t rush to throw away the profile scraps; they will still serve you as a block. Everything ingenious is simple!
How to choose sandpaper for working with wood?
There are quite a few characteristics by which sandpaper is classified. But the main and most significant parameter that you should focus on when choosing a sandpaper is the size of its abrasive grains - the so-called. graininess indicator. For specific tasks when working with wood, a certain type of grain size is selected.
TABLE: SELECTION OF ABRASIVE FOR WORKING WITH WOOD
Practice shows that to perform basic tasks, a master needs a set of five types of abrasives:
- P150; P180; P240(wood processing before applying finishing);
- P280; P400(interlayer and finishing sanding of finishing coatings).
You can read all about the intricacies of choosing sandpaper in.
Dry or wet sanding?
For intermediate sanding of finishing coatings - stain, varnish, polyurethane, etc. Traditionally, two techniques are used - dry or wet.
Dry grinding increases the efficiency of the abrasive and makes it possible to better control the work process, which is especially important at the stages of intermediate grinding of delicate coatings. The disadvantage of this technique is the rapid clogging of the skin. Sandpaper with an anti-clogging stearate coating partially compensates for this problem.
At wet grinding wooden products use mineral oil, white spirit or regular water as a moisturizer. soapy water. With this technology, the abrasive becomes clogged much slower and, accordingly, lasts longer. But the mess formed from foam and shavings significantly complicates the grinding process. There is a need to constantly wipe the surface and carefully monitor the result of grinding.
How to sand wood correctly?
Grinding technique . The wood is sanded with active movements along the grain or at a slight angle, but without excessive pressure on the block. Movements should be as light as possible, on the second or third pass using fine-grained sandpaper with virtually no pressure.
Preparing the surface for finishing . When preparing wood for applying a finishing coating (varnish, oil, stain, polyurethane, etc.), start working with P120 or P150 abrasive (depending on the nature of the irregularities). After that, move on to P180 grit and finish with P240 abrasive.
Intermediate grinding of coatings . When applying the finishing coating layer by layer, intermediate sanding of each layer is carried out with fine-grained sandpaper P280. For final polishing use P400 sandpaper. Use P600 grit abrasive to remove even the slightest imperfections in a glossy finish.
Requirements for finishing coatings to be sanded . Matte types coatings are not as demanding on the quality of sanding as glossy ones. At the same time, a dark stain will expose all the flaws of unfairly performed sanding.
Artificial stone is considered one of the the best materials For hard surfaces. To care for it and maintain its beauty, a minimum of effort is required. When properly maintained, the stone for a long time remains as elegant as when you first started using it. Although, like any other material, it needs to be looked after to maintain its impressive appearance.
Surface preparation
To begin with, it is necessary to carry out a rougher treatment - grinding. If you need to sand the seam after gluing or remove deep scratches, then you should start with an abrasive material marked 60 or 80. These numbers may be different, it all depends on the color and material, because their composition has different properties.
Grinding has several stages (passing through a sanding machine). The number of cycles depends on the material. Polishing and grinding must begin with bigger size abrasive, gradually moving to less.
Polishing and grinding of artificial stone
- These processes begin only after the adhesive joints have completely dried.
- Using a damp cloth and soap solution, remove all dirt.
- A vacuum cleaner is a good assistant when carrying out sanding work.
- After the first stage, use a sanding material with P180 grit, which will remove differences in the seam area.
- To obtain a matte surface, use an abrasive marked 240-320 at the final stage.
- With correctly fitted edges, the joint between the individual parts remains completely invisible after grinding.
- For daily use, it is recommended to use a matte or semi-gloss finish. This will make it easier to maintain decently appearance countertops made of artificial stone.
- By applying a sanding sequence from coarse to finer, all differences that have formed during the various phases are removed from the surface.
- Don't press too hard. The most optimal grinding technique is to move the turned-on tool across the surface with equal force.
- It is advisable to accompany each cycle with the direction “South-North, East-West”, as well as small in a circular motion, trying to capture the edges but not rounding them.
- The sanding disc must be cleaned before each step.
For protection, special polishes are used that create a protective film and protect against mechanical influences and dirt. The use of polish is allowed both for final polishing and for ordinary cleaning.
Polishing artificial stone Corian
As mentioned above, polishing not only improves the appearance, but also extends the service life of products made from it. Corian stone is polished using wheels of different grain sizes. At the initial stage, the product is polished with discs with a grit of 400, then 800 and 1500 are used. After the procedure, it is covered with protective equipment. Since this type of Corian product comes into contact with food products, then caring for them should be as safe as possible.
"Turtle" discs for polishing
Turtle diamond polishing discs are used to process straight or curved surfaces. They consist of a durable flexible base and a mixture of diamond powder and a durable heat-resistant polymer. Thanks to the neutral-colored binder, the discs do not leave streaks. Velcro located on back side, facilitates their quick replacement.
The work is performed sequentially with discs with diamond grits of 50, 100, 200, 400, 800, 1500, 3000 and BUFF inclusive. The last type is intended for final polishing. Diamond blade No. 50 has the coarsest grain, and No. 3000 has the finest.
Even a natural stone in some cases it can get damaged and scratched, which disrupts the decorative effect of the cladding. If you decide to restore the shiny surface yourself, find out in 10 minutes of reading how to polish and grind marble and granite yourself. All the secrets of our masters are collected in this article.
What you will need for work:
- A power tool is a grinder, without which grinding marble and granite with your own hands is simply impossible (it’s better if it’s a reliable Makita brand).
- A special “adapter” is a holder for grinding and polishing discs, the so-called “caliper”. It looks like a rubber disc with a special fastening. For processing curved surfaces, a convex rubber caliper is purchased; for smooth surfaces, a flat one with sufficient rigidity is purchased.
- Diamond grinding discs and polishing wheels (“turtles”) of different numbers.
