SU43159A1 - Diameter gauge - Google Patents

Description

The proposed device is intended to measure the diameters of very large parts (low pressure cylinders, (steam turbines, condensers, water turbines, etc.). Measuring the diameter directly, firstly, is inconvenient and, secondly, does not give adequate accuracy due to sagging roulettes, bar bends and so on.

In the instrument, a crank lever equipped with a toothed sector was used in the device for the pinion of the pointing arrow located on the axis. The inventor inserts a second lever into this known device, which is rigidly connected to the pinion axis of the pointing arrow and pivotally connected to the first lever. The diameter of the latter is determined from the magnitude of the divergence angle of the levers mounted on the circumference to be measured.

In FIG. 1 schematically depicts the proposed device; FIG. 2 shows a scale with a schematic representation of its interaction with parts of the device; and FIG. 3-scheme of the modified device.

The main part of the device consists of two steel levers 7 and 2 (Fig. 1), having three red-hot steel pins 3, with which the device is placed on the measuring circle. At the end of the lever 7, there are eyelets in which the axis of gear 5 is inserted, and on the crankshaft (172)

Chaga 2 has a toothed sector 4, which is engaged with gear 5 (both gear and sector are made of brass with possibly fine teeth, just like in watch movements; special attention should be paid to the possible careful fitting of the teeth in order to avoid gaps that would cause a dead stroke and would reduce the accuracy of the instrument readings).

In the first transmission of sector 4 and gear 5, it is possible to carry out a very large gear ratio of about 50-80 (take gear 5 of a sufficiently small diameter). A gear with a larger diameter sits on the same axis with gear 5, interlocking with gear 7, on the axis of which is arrow 8, moving with on a scale 9. The scale is calibrated in millimeters and figures stand after 10 mm. The second gear (gears b and 7) is performed with a gear ratio of the order of 5-8, and the total gear ratio of the device, depending on the factors mentioned above, i.e. compactness and accuracy, is in the range of 250-640.

In order to maximize the range of applicability of the device while maintaining a given accuracy throughout its duration, a scale consisting of 10-20 concentric circles is applied. It is easy to see that when

When measuring large diameters, the divergence angle of the arms is small, but it increases dramatically over small diameters. When measuring small diameters on the order of 3.0-5.0 mm, the main arrow 8 of the instrument makes 5-10 full revolutions and the count should be read on the appropriate circle of the scale 9. In order to facilitate the selection of this circle, an auxiliary arrow / 2 from scale 77. The arrow 72 sits on the same axis with the gear 10, coupled with the gear 5. The transmission to the auxiliary arrow is calculated so that the greatest deviations of the arrow 72 from its average position in one direction or the other do not exceed 70-80 °. The scale 77 is divided into divisions, corresponding to 100 mm changes in the measured diameter, besides, on the scale 77 there are also numbers indicating the sequence number of the circle of the main scale 9, which should be counted.

The positions indicated in the drawing relate to the measurement of the outer diameter (shaft diameter). If it is necessary to measure the inner diameter (diameter of the hole), then the divergence angle of the levers 7 and 2 will be of the opposite sign, and therefore both arrows will also rotate in the opposite direction. Therefore, in order to use the same device for measuring the diameters of the shaft and the diameters of the hole on the main scale of the device 9, the circles are painted alternately in two colors alternately: one color for measuring the diameters of the shaft, and the other for measuring the diameters of the; hole; similarly, both halves of the auxiliary scale 77 are painted over.

Both arrows 5 and 72 of the device should not be planted on their axes in a strictly fixed position, but should have devices that allow periodic checks of the device on a marking plate, or on circles whose diameters are precisely known in advance, to rearrange the arrows to the proper place if necessary, this is similar to how it is done in electrical devices. Finally, the device should have the following details: limit pins that would prevent the divergence of the levers 1 vi 2 by more than the maximum calculated angle in either direction to avoid disengaging sector 4 from the gear f5; a spring that must return the levers to their initial position; a stopper that would not allow the arms to swing relative to each other when carrying the device and release them only at the time of the measurement (all these auxiliary devices are not shown in the drawing).

Gears to the arrow can be replaced by friction ones, namely instead of a gear a smooth polished roller (steel) is placed, the diameter of which is maintained with the maximum possible accuracy, and along the arc of the sector the rubber band is tightened, the ends of which are fixed on the nuts moving along the guides. In this way, it is possible to vary the tension of the rubber, and therefore to adjust the pressing of the rubber on the roller associated with the arrow. Due to such a friction gear, the dead stroke, which is inevitable during gearing, is completely eliminated, and a larger gear ratio can also be realized.

The modified device consists not of two, but of three levers, and the measurement of the diameter of a circle is made not by three, but by four points. The meaning of this design is to better use the length of the instrument, i.e., the possibility of significantly reducing the gear ratio of the instrument (by increasing the divergence angle of the levers) and reducing the influence of local roughness, and therefore increasing the accuracy of readings.

The device (Fig. 3) consists of a middle lever 2 (of a length of, for example, 600 mm) and two extreme levers 7 and 5 connected with it by means of hinges (of a length of 300 mm). The middle lever 2 has two pairs of support pins (the distance between the pins in the direction perpendicular to the plane of the drawing is 100, -150 mm). Extreme levers 7 and 5 are made elbows, and on their extensions the toothed sectors of 4 liters are fixed 5, which engage with gears of 6 liters 7 having one geome