RU2332283C1 - Fly hob - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: cutter is designed for cutting worm gears and consists of a case and an incomplete loop in form of a tooth. To increase efficiency and quality of gear machining, the cutter is made as an assembly clamped on a disposable carbide blade in form of a trapezium with linear lateral profiled cutting edges, freely installed on pivot, which is pressed into a removable blade, with provision for radial displacement in the groove of the case with screwing screws for pressing the plates to the peripheral surface of the case. The incomplete loop of the tooth is made from a bundle of wires in a form of trapezium with linear lateral profiled cutting edges, overhanging the plate by a preload, and fixed by a pulling rod, passing through an opening in each bundle of wires and joining the removable blade to the rear plank using nuts. On the peripheral surface of the case there is a groove in the form of dovetail, in which the above mentioned plank and wire bundle are put with provision for circular movement.

EFFECT: increased efficiency and quality of gear machining.

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Description

The invention relates to mechanical engineering and can be used to cut the teeth of a worm gear cylinder.

Known prefabricated worm milling cutter for cutting worm wheels, consisting of a mounted cylindrical worm with an incomplete round tooth and an eccentric ring entering the worm hole, which, when the cutter is mounted on the spindle of the hobbing machine, provides the formation of a rear angle and a constant tooth outflow [1].

A disadvantage of the known cutter is low productivity, roughness, machined surface and low resistance due to the fact that it is made integral and does not allow the use of its body after all regrinding of the tooth, and this increases the cost of the tool, in addition, when regrinding, the cutter must be removed from machine and transfer to the grinding machine.

The objective of the invention is to increase the productivity and quality of gear processing by eliminating the backing operation and the introduction of a combined needle-milling gear treatment.

The problem is solved using the proposed worm mill-flapper for cutting worm wheels in the form of a cylindrical worm, consisting of a body and an incomplete turn in the form of a tooth, while it is made of a team with mechanical fastening of a non-turning carbide plate in the form of a trapezoid with rectilinear side profiling cutting edges, freely mounted on a pin, which is pressed into an insert knife, which has the ability to radially move into the groove of the housing when screwing in screws for holding the plate to the peripheral surface of the body, while an incomplete tooth turn is made of a bundle of wire tufts in the form of a trapezoid with straight lateral profiling cutting edges protruding above the insert by the amount of interference, and secured with a rod passing through the hole in each bundle and connecting the insert knife with a back plate using a nut, a dovetail-shaped groove is made on the peripheral surface of the body, in which the above-mentioned back plate and tufts roving pile.

The design features of the worm needle-cutter are illustrated by drawings.

Figure 1 presents the proposed worm needle-fly-fly, end view; figure 2 is a view according to B in figure 1; figure 3 is a view along a in figure 1; figure 4 - section G - G in figure 5 of the element In figure 1; figure 5 is a top view of the element In figure 4; figure 6 is a section D - D in figure 5 of the element In figure 1; Fig.7 - design of a pile of pile of wire from which an incomplete round of tooth is recruited; on Fig - section E - E in Fig.7; in Fig.9 - a package of bundles of wire pile under load in the working position, located in the cavity between the cut teeth of the machined wheel.

The proposed flywheel milling cutter serves for cutting worm wheels by the rolling method, in which the worm engages with the worm wheel, where the proposed worm cutter is used as the worm, and the workpiece is used as the worm wheel. The fly worm-mill is a cylindrical worm and consists of a housing 1 and an incomplete turn - tooth 2. The worm-mill-fly is made by a team with mechanical fastening by a non-sharpened carbide cutting insert 3 in the form of a trapezoid with straight side profiling cutting edges.

The cutting insert 3 is freely mounted on the pin 4, which is pressed into the hole of the insert knife 5. The insert knife 5 has the ability to radially move into the groove 6 of the housing 1 when the screws 7 are screwed in.

Screws 7, when they are screwed into the housing 1, the plate 3 is pressed against the peripheral surface of the housing 1. The surface of the insert knife 5, on which the cutting plate 3 rests, is cut and sharpened so that a negative rake angle and positive rear angles along the tooth profile are formed.

A fly-type worm milling cutter is an incomplete turn of 2 worms with parameters of the producing helical surface of the worm milling cutter designed for a given cut worm wheel with a step t.

An incomplete turn 2, in addition to the cutting insert 3, is made of a package of bundles of wire pile 8. The package is made in the form of a trapezoid with rectilinear lateral profiling cutting edges protruding above the insert 3 by the amount of interference i (see FIG. 2). The bundle of wire bundles 8 is fixed to the housing by known methods.

In the proposed design, as an option, an original method for attaching bundles of wire pile, which is presented below, is developed.

First, a pile of pile 9 is made from individual wires connected, for example, by spot welding, as shown in Figs. 7-8. In this bundle, radially arranged wires 9 _P and wires located in the circumferential direction, 9 _O , are distinguished. Each bundle of pile 9 has an opening 10 and the bottom part in the form of a dovetail 11. The bundles of wire pile 9 with the lower part are installed in the groove 12 on the housing 1 and are strung on the rod 13. The rod 13 is rigidly fixed at one end, for example, pressed into the insert knife 5, and at the second end of the threaded thread. On the peripheral surface of the housing, a groove 12 in the form of a “dovetail” is made over the entire length of the incomplete turn.

The final fastening of the wire pile 9 on the body is carried out by tightening the bundles with a nut 14, screwed onto the threaded end of the rod 13, on which the back plate 15 is pre-installed. When tightening the nut 14, the tufts of the wire pile are circumferentially moved and sealed, as well as they are rigidly connected to the body.

After the general assembly, it is necessary to grind the needle part of the coil along the profile, taking into account the interference fit i, before gearing.

Example. 29 teeth were milled, m = 3 of a worm wheel made of: hub made of steel 45, crown made of bronze А9Ж3А, on a gear-milling machine mod. 53A20B, proposed by the worm needle-mill, equipped with a VK4 carbide cutting insert used for roughing, and a bundle of wire bundles for final finishing. These transitions were made at the same time due to the design peculiarities of the flying worm needlefish. According to the traditional standard technological process, a shaving machine, for example, mod, was used for the final finishing of such a worm wheel. 5B702V, on which sheving was finally made.

Processing was carried out according to the tangential feed method [2]. During operation, the machined wheel engages with a single-entry worm, therefore, we perform needle milling with a feed of 0.9 ... 0.15 mm / rev table, cutting speed of 12 ... 18 m / min. The ability to adjust the cutting insert in the housing in height allows you to get a uniform quality of engagement of the worm wheels. Finishing of the teeth is carried out after rough milling, using tufts of wire pile, which are installed behind the cutting insert in the form of an incomplete turn 2. The following allowances for fine needle-milling are recommended, see table 1.

Table 1. Tolerances (mm) on the thickness of the tooth of the worm wheels

Module mm Under needle milling Up to 2 0.35 St. 2 to 4 0.35 ... 0.55 "4" 6 0.55 ... 0.80 "6" 8 0.80 ... 1.00 "8" 10 1.00 ... 1.30 "10" 14 1.00 ... 1.50

As a pile, a steel spring wire with a diameter of 0.5 ... 1.0 mm from 65G steel is used. To carry out the finishing treatment, it is necessary that the hardness and tensile strength of the material of the wire elements of the pile be higher than these parameters of the material of the workpiece by 1.5 ... 2 times, the ratio l / I, where I is the smallest inertia radius of the cross section of the wire elements, was in the range of 50 ... 100, and the coefficient K _{p the} density of the wire pile in the range of 0.7 ... 0.9; the tightness should be - i = 0.7 ... 1.5 mm.

In the process of processing the depression of the workpiece of the worm wheel, the tufts of pile 9 _O are placed between the teeth (see Fig. 9) and pressed against the workpiece with an interference fit. Due to the fact that the tufts of pile 9 _{O of the} circumferential direction work at their two ends, the length l _O will affect the force on the machined side surfaces of the teeth. The main force impact on the surface being machined is carried out by the first 9 _O wire elements with the longest free length l and deflection f. The wire elements adjacent to them elastically compress them, slightly increasing the concentrated total effect on the treated surfaces.

Tests of the proposed worm needle-mill worms showed that the force of pressing the beam to the workpiece surface is 200 ... 600 N per 10 mm of the width of the working surface of the tool, and the tangential component of the cutting force is 150 ... 550 N.

For processing the proposed tool must comply with the conditions

To _p = p / σ _in = 1.5 ... 2.0,

where p is the pressure during acupuncture, MPa;

σ _in - the tensile strength of the material of the workpiece, MPa.

The choice of the corresponding pressure p depends on the physicomechanical properties of the material of the wire pile, on the rigidity and density of the latter, as well as on the interference fit [3].

The proposed worm needle-cutter increases the productivity by combining roughing and finishing operations with a high-speed plate and tufts of wire pile, reduces the number of operations and the number of jobs, eliminates the backing operation due to the use of a non-rotatable carbide plate with mechanical fastening, and also improves the quality and accuracy of gear processing the introduction of combined acupuncture gear.

Information sources

1. A.S. USSR No. 107509, IPC B23F 21/18. Flying worm mill for cutting worm wheels. I.S. Sahno. Application 7102/455163, 07/05/1955 - prototype.

2. Reference technologist-machine builder. In 2 t. T. 1. Ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering. 1986. S. 371-372.

3 Gavrilenko I.G. A method of combining preliminary and final needle-milling stripping of cylindrical parts // Automation and modern technology. - 1992. - No. 9. - P.27-30.

Claims (1)

Cylindrical worm gear for cutting worm wheels in the form of a cylindrical worm, consisting of a body and an incomplete turn in the form of a tooth, characterized in that it is made of a team with mechanical fastening of a trapezoidal carbide plate in the form of a trapezoid with straight side profiling cutting edges freely mounted on a pin , which is pressed into an insert knife having the ability to radially move into the groove of the housing when screwing in screws to hold the plate against the peripheral surface of the housing, In this case, an incomplete tooth revolution is made of a bundle of wire tufts in the form of a trapezoid with straight lateral profiling cutting edges protruding above the insert by the amount of interference, and secured with a rod passing through the hole in each bundle and connecting the insert knife with the back plate using a nut , a dovetail-shaped groove is made on the peripheral surface of the housing, in which the aforementioned back plate and bundles of wire pile are located with the possibility of circumferential movement.

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