Target: learn how to set up a machine for processing outdoor conical surfaces by turning the upper part of the caliper; check the machined conical surface in size with a caliper, caliber (sleeve), universal goniometer.
Material and technical equipment: TV1A-616 machine poster; Toolkit, cutters with a wide cutting edge and ShTs-1.
- Familiarize yourself with the methodological instructions;
- Answer test questions;
- Obtain permission to perform work;
- Get an assignment from a teacher;
- Perform the processing of the cone in one of the ways on the instructions of the teacher;
- Coordinate the processing of the cone with technological map;
- Submit the completed product for evaluation;
Theoretical introduction.
The conical surface is characterized by the following parameters (Fig. 1): smaller d and larger D diameters and distance 1 between the planes in which circles with diameters d and D are located.
The angle α is called the angle of inclination of the cone, and the angle 2α is called the angle of the cone. The ratio K \u003d (D- d) / l is called taper and is usually denoted by a ratio, for example, 1:20 or
1:50, and in some cases a decimal fraction, such as 0.05 or 0.02. The ratio Y \u003d (D - d) / 2l \u003d tg α is called the slope.
When machining shafts, there are often transitions between machined surfaces that have conical shape, drills, the length of the cone does not exceed 50 mm, then it is worked with a wide cutter (Fig. 2). In this case, the cutting edge of the cutter must be set in terms of the axis of the centers at an angle corresponding to the angle of inclination of the cone on the workpiece. The cutter is fed in the transverse or longitudinal direction. To reduce the distortion of the generatrix of the conical surface and the deviation of the angle of inclination of the cone, the cutting edge of the cutter is set along the axis of rotation of the part.
Rice. 2. Processing the conical surface with a wide cutter.
It should be borne in mind that when processing a cone with a cutter with a cutting edge longer than 10 - 15 mm, vibrations may occur. The level of vibration increases with an increase in the length of the workpiece and with a decrease in its diameter, as well as with a decrease in the angle of inclination of the cone, with the location of the cone approaching the middle of the part and with an increase in the overhang of the cutter and with insufficiently strong fixing. With vibrations, traces appear and the quality of the treated surface deteriorates. When machining rigid parts with a wide cutter, vibrations may not occur, but at the same time, the cutter may be displaced under the action of the radial component of the cutting force, which can lead to a misconfiguration of the cutter to the required angle of inclination. Cutter offset also depends on the machining mode and feed direction.
Conical surfaces with large slopes can be machined with the upper slide of the caliper with the tool holder turned (Fig. 3) by an angle α equal to the angle of inclination of the machined cone. The cutter is fed manually (with the handle of the upper slide), which is a disadvantage of this method, since uneven feed leads to an increase in the roughness of the machined surface. According to this method, conical surfaces are processed, the length of which is commensurate with the stroke length of the upper slide.
Fig. 3. Machining of the conical surface with the upper slide of the caliper rotated through the angle α.
Rice. 4. Processing of the conical surface when the tailstock is displaced.
Conical surfaces of great length with an inclination angle of α = 8 - 10° can be machined with a shift in the rear center (Fig. 4). The amount of displacement of the tailstock is determined by the scale printed on the end face of the base plate from the flywheel side, and the risk on the end face of the tailstock housing. The division price on a scale of 1 mm. In the absence of a scale on the base plate, the displacement of the tailstock is measured using a ruler attached to the mountain plate. The tailstock displacement value is controlled using a stop (Fig. 5, a) or an indicator (Fig. 5, b).
The indicator is installed in the tool holder, brought to the part until it touches the tailstock and moved (by a caliper) along the generatrix of the part. The tailstock is displaced until the deviation of the indicator needle is minimal along the length of the generatrix of the conical surface, after which the tailstock is fixed. The same conicity of parts in a batch processed by this method is ensured with minimal deviations of the workpieces along the length and center holes size (depth). Since the displacement of the centers of the machine causes wear of the center holes of the workpieces, the conical surfaces are pre-treated, and then, after correcting the center holes, the final finishing is performed. To reduce the breakdown of the center holes and the wear of the centers, it is advisable to use centers with rounded tops.
Rice. 6. Processing of a conical surface using copiers with longitudinal (a) and transverse (b) movement.
Conical surfaces with α = 0 - 12° are processed using copiers. A plate 1 is attached to the machine bed (Fig. 6, a) with a copy ruler 2, along which the slider 5 moves, connected to the caliper 6 of the machine by a rod 7 using a clamp 8. For free movement of the caliper in the transverse direction, it is necessary to disconnect the cross feed screw. With the longitudinal movement of the caliper 6, the cutter receives two movements: longitudinal from the caliper and transverse from the copier ruler 2. The angle of rotation of the ruler relative to axis 3 is determined by the divisions on the plate 1. The ruler is fixed with bolts 4. The cutter is fed to the cutting depth with the handle for moving the upper slide of the caliper.
The processing of the outer and end conical surfaces 9 (Fig. 6, b) is carried out according to the copier 10, which is installed in the tailstock quills or in the turret of the machine. In the tool holder of the transverse caliper, a fixture 11 with a copy roller 12 and a pointed through cutter is fixed. During the transverse movement of the caliper, the copier pin, in accordance with the profiles of the copier 10, receives a longitudinal movement of a certain amount, which is transmitted to the cutter. The outer conical surfaces are machined with through cutters, and the inner ones with boring cutters.
a) b)
c) d)
Rice. Fig. 7. Processing of a conical hole in a solid material: a - finished (after finishing reaming) hole with diameters d and D along the length l, b - cylindrical hole for a rough reamer, c - removal of the allowance with a rough reamer, d - removal of the allowance with a semi-finishing reamer.
To obtain a conical hole in a solid material (Fig. 7, a - d), the workpiece is pre-processed (drilled, countersinked, bored), and then finally (deployed, bored).
Test questions.
- What are the methods of processing conical surfaces?
- How are internal conical surfaces machined?
- How are external and internal conical surfaces checked?
- Requirements for a tool for processing conical surfaces.
- When is one method used?
Tapered surfaces can be processed in several ways: with a wide cutter, with the upper slide of the caliper turned, with the tailstock body displaced, with the help of a tapered ruler and with the help of special copying devices.
Processing of cones with a wide cutter. Conical surfaces 20-25 mm long are processed with a wide cutter (Fig. 151, a). To obtain the required angle, an installation template is used, which is applied to the workpiece, and a cutter is brought to its inclined working surface. Then the template is removed and the cutter is brought to the workpiece (Fig. 151.6). Processing of cones with the upper slide of the caliper turned (Fig. 152, a, b). The rotary plate of the upper part of the caliper can be rotated relative to the cross slide of the caliper in both directions; To do this, you need to release Guy-
152 PROCESSING OF TAPERED AT - " SURFACES (CONES) WITH THE TOP CALIPER SLIDE TURNED:
Ki screws fixing the PLATE. Control of the angle of rotation with an accuracy of one degree is carried out by divisions rotary plate.
Advantages of the method: the possibility of processing cones with any angle of inclination; ease of machine setup. Disadvantages of the method: the impossibility of processing long conical surfaces, since the processing length is limited by the stroke length of the upper support (for example, for a 1KG2 machine, the stroke length is 180 mm); turning is performed by manual feed, which reduces productivity and degrades the quality of processing.
When processing with the upper part of the caliper turned, the feed can be mechanized using a device with a flexible shaft (Fig. 153). Flexible shaft 2 receives rotation from the lead screw or from the machine shaft through bevel or helical gears.
(IK620M, 163, etc.) with a mechanism for transferring rotation to the screw of the upper part of the caliper. On such a machine, regardless of the angle of rotation of the upper caliper. you can get automatic feed.
If the outer conical surface of the shaft and the inner conical surface of the sleeve are to be mated, then the taper of the mating surfaces must be the same. To ensure the same taper, the processing of such surfaces is performed without readjusting the position of the upper part of the caliper (Fig. 154 a, b). At the same time, a boring cutter with a head bent to the right of the rod is used to process the taper hole, and the spindle is rotated in reverse.
Adjustment of the rotary plate of the upper part of the caliper to the desired angle of rotation is carried out using an indicator according to a pre-fabricated reference part. The indicator is fixed in the tool holder, and the tip of the indicator is set exactly in the center and brought to the conical surface of the standard near the smaller section, while the indicator needle is set to "zero"; then the caliper is moved so that the indicator pin touches the workpiece, and the needle is at zero all the time. The position of the caliper is fixed with clamping nuts.
Machining of conical surfaces by shifting the tailstock. Long external tapered surfaces are machined by offsetting the tailstock body. The workpiece is installed in the centers. The body of the tailstock with the help of a screw is displaced in the transverse direction so that the workpiece becomes “skewed”. When turned on
Feeding the carriage of the caliper, the cutter, moving parallel to the axis of the spindle, will grind the conical surface.
The displacement value H of the tailstock body is determined from the LAN triangle (Fig. 155, a):
H \u003d L sin a. It is known from trigonometry that for small angles (up to 10 °) the sine is practically equal to the tangent of the angle. For example, for an angle of 7°, the sine is 0.120 and the tangent is 0.123.
As a rule, workpieces with small slope angles are processed by the tailstock displacement method, so we can assume that sina = tga. Then
Ig. g D-d L D-d
And \u003d L tg a ~ L ------------- \u003d ----- MM.
Tailstock offset by ±15 mm is allowed.
Example. Determine the amount of displacement of the tailstock for turning the workpiece shown in fig. 155.6 if L=600 mm /=500 mm D=80 mm; d=60 mm.
I=600----===600 ■_______=12mm.
The amount of displacement of the body of the tailstock relative to the plate is controlled by divisions at the end of the plate or with the help of a transverse feed dial. To do this, a bar is fixed on the tool holder, which is brought to the tailstock quill, while the position of the limb is fixed. Then the cross slide is retracted back by the calculated value along the limb, and then the tailstock is displaced until it comes into contact with the bar.
The adjustment of the machine for turning cones by shifting the tailstock can be performed according to the reference part. To do this, the reference part is fixed in the centers and the tailstock is displaced, controlling the parallelism of the generatrix of the reference part to the feed direction with the indicator. For the same purpose, one can use
1 55 PROCESSING OF THE EXTERNAL CONIC - SURFACES (CONES) BY THE METHOD OF OFFSETTING THE TAILSTOCK:
Use a cutter and a strip of paper: the cutter is in contact with the conical surface along a smaller and then along a larger diameter so that a strip of paper is pulled between the cutter and this surface with some resistance (Fig. 156).
According to the law of conservation of energy, the energy spent on the cutting process cannot disappear: it turns into another form - into thermal energy. The heat of cutting occurs in the cutting zone. In the process of cutting more ...
A feature of modern technical progress is automation based on the achievements of electronic technology, hydraulics and pneumatics. The main directions of automation are the use of tracking (copier) devices, automation of machine control and control of parts. Automatic control …
Methods for processing conical surfaces. The processing of conical surfaces on lathes is carried out in the following ways: by turning the upper slide of the caliper, by transverse displacement of the tailstock body, using a conical ruler, with a special wide cutter.
With the use of turning the upper sled of the caliper, grind short conical surfaces with different angle slope a. The upper slide of the caliper is set to the value of the slope angle according to the divisions applied around the circumference of the support flange of the caliper. If a in In the drawing of the part, the slope angle is not specified, then it is determined by the formula: and the table of tangents.
The feed with this method of operation is carried out manually by rotating the handle of the screw of the upper slide of the caliper. The longitudinal and cross slides must be locked at this time.
Conical surfaces with a small cone angle with a relatively long workpiece length handle with applying the transverse displacement of the tailstock body. With this method of processing, the cutter moves with a longitudinal feed in the same way as when turning cylindrical surfaces. The conical surface is formed as a result of the displacement of the rear center of the workpiece. When the rear center is displaced “away from you”, the diameter D the large base of the cone is formed at the right end of the workpiece, and when shifted "towards itself" - at the left. The amount of transverse displacement of the tailstock housing b determined by the formula: where L- distance between centers (length of the entire workpiece), l- the length of the conical part. At L = l(cone along the entire length of the workpiece). If K or a is known, then, or Ltga. Rear body offset money produced using the divisions applied on the end of the base plate, and the risk on the end of the tailstock housing. If there are no divisions at the end of the plate, then the tailstock body is displaced using a measuring ruler.
Tapering using a tapered ruler is carried out with the simultaneous implementation of the longitudinal and transverse feeds of the cutter. The longitudinal feed is produced, as usual, from the running roller, and the transverse feed is carried out by means of a conical ruler. A plate is attached to the machine bed , on which the tapered ruler is installed . The ruler can be rotated around the finger at the required angle a° to the axis of the workpiece being processed. The position of the ruler is fixed with bolts . The slider sliding along the ruler is connected to the lower transverse part of the caliper by means of a clamp rod . In order for this part of the caliper to slide freely along its guides, it is disconnected from the carriage , by removing or disabling the cross feed screw. If now the carriage is informed of the longitudinal feed, then the thrust will move the slider along the tapered ruler. Since the slider is connected to the cross slide of the caliper, they, together with the cutter, will move parallel to the tapered ruler. Thus, the cutter will process a conical surface with a slope angle equal to the angle of rotation of the cone ruler.
The depth of cut is set using the handle of the upper slide of the caliper, which must be rotated 90° from its normal position.
Cutting tools and cutting conditions for all considered methods of processing cones are similar to those for turning cylindrical surfaces.
Tapered surfaces with short taper lengths can be machined special wide cutter with an angle in the plan corresponding to the angle of the taper. The feed of the cutter in this case can be longitudinal or transverse.
Outer and inner cones up to 15 mm long are machined with cutter 1, the main cutting edge of which is set at the required angle a to the cone axis, carrying out longitudinal or transverse feed (Fig. 30, a). This method is used when the workpiece is rigid, the taper angle is large, and the accuracy of the taper angle, surface roughness and straightness of the generatrix are not high requirements.
Rice. thirty.
Inner and outer cones of small length (but longer than 15 mm) at any angle of inclination are processed with the upper slide turned (Fig. 30, b). The upper slide of the caliper 1 is set at an angle in the axial line of the machine, equal to the angle of inclination of the cone being turned, according to the divisions on the flange 2 of the rotary part of the caliper. The angle of rotation reports from the risk applied on the cross slide of the caliper.
The processing of external cones with a displaced tailstock is used for workpieces of relatively large length with a small slope angle (Fig. 30, c). In this case, the workpiece 2 is fixed only in the centers 1. Taking into account the inevitability of wear of the center surfaces even at small taper angles, the processing is carried out with a cutter 3 in two steps. First, the cone is drafted. Then the center holes are corrected. This is followed by a clean cut. To reduce the development of center holes in such cases, centers with vertices in the form of a spherical surface are successfully used. The transverse displacement of the tailstock is usually allowed no more than 1/5 of the length of the workpiece.
Turning the outer and inner conical surfaces using a universal copier ruler is used when processing workpieces of any length with a small taper angle, up to about 12 ° (Fig. 30, d). The copy ruler 1 is installed on the plate 5 parallel to the forming conical surface to be turned, while the upper part of the support 4 is rotated by 90°. The reading of the angle of rotation of the ruler during adjustment is made according to the divisions (millimeter or angular) marked on the plate 5. The plate is attached with brackets to the machine frame. After turning the ruler around the axis at the required angle a, it is fixed with a nut 6. In the groove of the ruler there is a slider 7, rigidly connected to the cross slide 2 of the caliper. When turning, the cutter, together with the caliper, moves in the longitudinal direction and, under the action of a slider sliding in the slot of the ruler, in the transverse direction. In this case, a conical surface with an angle at the top of 2a will be turned. The angle of rotation of the ruler should be equal to the angle cone slope. If the scale of the ruler has millimeter divisions, then the rotation of the ruler is determined by one of the following formulas:
where h is the number of millimeter divisions of the scale of the copier ruler; H is the distance from the axis of rotation of the ruler to its end, on which the scale is applied; D is the largest diameter of the cone; d is the smallest diameter of the cone; tga is the angle of inclination of the cone; K - taper
(K= (D-d)/l); l is the length of the cone.
When a>12°, the so-called combined processing method is used, in which the angle of inclination is divided into two angles: a1 = 11-12°; a2 = a - a1. The copy ruler is set at an angle a1 = 12°; and the tailstock is displaced to process a conical surface with an inclination angle a2=a-12°.
The method of processing conical surfaces with the help of a copier ruler is quite universal and provides high accuracy, and the adjustment of the ruler is convenient and fast.
Regardless of the method of processing the cone, the cutter is set exactly at the height of the machine centers.
The machined end of the workpiece should protrude from the chuck no more than 2.0 - 2.5 of the workpiece diameter. The main cutting edge of the cutter using a template or goniometer is set under desired angle cone. You can grind the cone with transverse and longitudinal feeds.
When the cone of the workpiece protrudes from the chuck by more than 20 mm or the length of the cutting edge of the cutter is more than 15 mm, vibrations occur that make it impossible to process the cone. Therefore, this method is used to a limited extent.
Remember! The length of the cone being machined wide incisors, should not exceed 20 mm.
Questions
- When is a cone processed with wide incisors?
- What is the disadvantage of cutting cones with wide cutters?
- Why should the workpiece cone not come out of the chuck more than 20 mm?
To turn short outer and inner conical surfaces on a lathe with a taper angle α = 20°, you need to turn the upper part of the support relative to the machine axis at an angle α.
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With this method, the feed can be done by hand by turning the screw handle of the upper part of the caliper, and only the most modern lathes have a mechanical feed of the upper part of the caliper.
If the angle a is given, then the upper part of the caliper is rotated using the graduations, usually marked in degrees on the disk of the rotary part of the caliper. You have to set the minutes by eye. Thus, to rotate the upper part of the caliper by 3°30′, you need to put a zero stroke between approximately 3 and 4°.
Disadvantages of turning tapered surfaces with the rotation of the upper part of the caliper:
- productivity decreases and the cleanliness of the treated surface deteriorates;
- the resulting conical surfaces are relatively short, limited by the stroke length of the upper part of the caliper.
Questions
- How should the upper part of the caliper be installed if the angle a of the cone slope is specified according to the drawing with an accuracy of 1 °?
- How to install the upper part of the caliper if the angle is set with an accuracy of 30' (up to 30 minutes)?
- List the disadvantages of turning conical surfaces with the rotation of the upper part of the caliper.
Exercises
- Set up the machine to turn a tapered surface at 10°, 15°, 5°, 8°30', 4°50'.
- Make a center punch according to the one below.
Technological map for the manufacture of center punch
|
blank | Forging | ||||||||||
| Material | Steel U7 | |||||||||||
| No. p / p | Processing sequence | Instruments | Equipment and fixtures | |||||||||
| worker | marking and control and measuring | |||||||||||
| 1 | Cut off the workpiece with an allowance | Hacksaw | Vernier caliper, measuring ruler | Bench vice | ||||||||
| 2 | Cut end to length with allowance for centering | scoring cutter | Calipers | Lathe, three-jaw chuck | ||||||||
| 3 | Center on one side | Center drill | Calipers | Lathe, drill chuck | ||||||||
| 4 | Roll the cylinder on the length L— (l 1 +l 2) |
|
knurling | Calipers | Three-jaw lathe chuck, center | |||||||
| 5 | Turn the cone at length l 1 at an angle α, turn the point at an angle of 60° | Cutter through bent | Calipers | |||||||||
| 6 | Cut the end with a centering on the length l | Cutter through bent | Calipers | Three-jaw lathe chuck | ||||||||
| 7 | Turn the cone of the striker at a length l 2 | Cutter through bent | Calipers | Three-jaw lathe chuck | ||||||||
| 8 | Turn the rounding of the striker | Cutter through bent | Radius template | Three-jaw lathe chuck | ||||||||
"Plumbing", I.G. Spiridonov,
G.P. Bufetov, V.G. Kopelevich
Conical holes with a large angle at the top are processed as follows: the workpiece is fixed in the headstock chuck and, to reduce the boring allowance, the hole is processed with drills of different diameters. First, the workpiece is machined with a smaller diameter drill, then with a medium diameter drill, and finally with a large diameter drill. The sequence of drilling a part for a cone Boring conical holes is usually by turning the upper part ...
When processing conical surfaces, the following types of rejects are possible: irregular taper, deviations in the size of the cone, deviations in the dimensions of the diameters of the bases with the correct taper, non-straightness of the generatrix of the conical surface. Incorrect taper is obtained mainly due to an inaccurately set cutter, inaccurate rotation of the upper part of the caliper. By checking the installation of the tailstock housing, the upper part of the caliper before starting processing, this kind of…
In the sixth and seventh grades, you were introduced to the various jobs that can be done on a lathe (for example, external cylindrical turning, part cutting, drilling). Many workpieces processed on lathes can have an external or internal tapered surface. Parts with a conical surface are widely used in mechanical engineering (for example, a drill spindle, drill shanks, centers lathe, tailstock quill hole)….