US3115704A

US3115704A - Burnishing box tools

Info

Publication number: US3115704A
Application number: US165087A
Authority: US
Inventors: Fawell Stanley Nathan
Original assignee: Fletcher Brock and Collis Ltd
Current assignee: Fletcher Brock and Collis Ltd
Priority date: 1961-01-12
Filing date: 1962-01-09
Publication date: 1963-12-31
Anticipated expiration: 1980-12-31
Also published as: GB920818A

Description

Dec.

s. N. FAWELL 3,115,704

BURNISHING BOX TOOLS Filed Jan. 9, 1962 INVENTOR STANLEY N. FAWELL.

ATTORNEYS 3,115,704 BURNISHHNG BOX T0015 Stanley Nathan Fawell, llford, Essex, England, assignnr to Fletcher, Brock dz Collis, Ltd, Hainanlt, England, a company of Great Britain Filed Jan. 9, 1962, Ser. No. 165,087 Claims priority, application Great Britain Jan. 12, 1961 4 (llairns. (Cl. 29-566) This invention relates to burnishing box tools suitable for use in automatic machine tools, being box tools (i.e. tools adapted to be applied to a relatively rotating workpiece held by one end over the free end thereof) having a cutting bit and burnishing members. Such a tool will be referred to herein as a tool of the kind specified.

Tools of the kind specified are used for providing the workpiece, for example the shank of a bolt, with a smoothed, burnished, cylindrical surface. The tool is applied over a free end of the relatively rotating workpiece and is advanced along the workpiece towards the chuck or collet which holds it, during which movement the bit removes surplus material and forms a cylindrical surface while the burnishing members (usually hardened steel wheels) smooth out the marks made by the bit and proyide a burnished surface.

One problem which is encountered with such tools is the removal of the tool from the workpiece. If the bit is not retracted from the workpiece it may score the workpiece as the tool is withdrawn. Also, the tip of the bit sometimes tends to dig into the workpiece when it comes up against a shoulder at the end of the cylindrical surface, e.g. the lunderside of the head, in the case of a bolt. If the bit is non-retractable, withdrawal of the tool is difiicult in such circumstances. Various types of openable box tools have been devised in attempts to solve these problems, but these have the disadvantages that they must be opened and re-closed by the machine operator, or are very complicated.

It is an object of the invention to provide a bu-rnishing box tool of the kind specified which opens automatically upon withdrawal of the workpiece and which is of relatively simple construction.

According to the present invention, in a burnishing box tool of the kind specified the bit is mounted on a carrier which is capable of limited movement relative to the body of the tool between an advanced position in which the tip of the bit is at its nearest to the axis of the workpiece and farthest from the front of the tool and a retracted position in which the tip of the bit is at its farthest from the axis of the workpiece and nearest to the front of the tool.

Thus, as the tool is applied to the workpiece the reaction on the bit forces it rearwardly with respect to the body of the tool and inwardly towards the axis of the workpiece, whereas when the tool is being withdrawn the reaction on the bit forces it forwardly with respect to the body of the tool and outwardly away from the axis of the workpiece.

If desired, the bit carrier may be spring-biased towards its retracted position.

In one form of the invention the bit carrier is pivoted to the body' of the tool about an axis lying in a transverse plane perpendicular to the axis of the workpiece and to the rear of the parallel transverse plane containing the tip of the bit, whereby the reaction on the bit when the tool is applied to the workpiece tilts the bit carrier towards the workpiece, whereas the opposite reaction when the tool is being withdrawn tilts the bit carrier away from the workpiece.

The range of movement of the bit carrier can be very small, e.g. only a thousandth of an inch or so at the tip 3,1157% Patented Dec. 31, 1963 ice of the bit. A suitable adjustable stop, or adjustable stops, may be provided for determining the limiting positions.

The bit may be adjustably clamped in a slide way in the bit carrier so that its position can be adjusted.

The invention may be performed in various ways and a specific embodiment will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a side elevation of a simplified form of box tool embodying the invention, diagrammatically exaggerated to show the principle of operation;

FIGURE 2 is a side elevation of a practical embodimerit;

FlGURE 3 is an end view looking from the right in FIGURE 2;

FIGURE 4 is an end view looking from the left in FIGURE 2, the tool having been rotated anti-clockwise through from the position in which it is shown in FIGURE 2; and

FIGURE 5 is a section taken on the line VV in FIGURE 4.

Referring to FIGURE 1, the box tool indicated generally by the reference numeral 10 comprises a body 11 having fixed thereto a shank 1 2 by which the tool can be mounted in a machine such as a lathe, e.g. in a collet mounted in the 'tailstock. The box tool 1t is adapted to machine a cylindrical surface on a workpiece 13 by means of a cutting bit 14, and to b-urnish the machined surface by means of at least one burnishing roll 15, as the workpiece 13 is rotated relatively to the box tool about an axis 16 and advanced in the direction of the arrow 17. The workpiece axis 16 is coincident with the axis of the shank 12. The body 11 has a well 18 into which the tip of the workpiece 13 can enter.

The burnishing roll 15 is mounted on an axle 19 in a support member 20 clamped to the body 11. The support member can be adjusted relative to the axis 16 in :order that the box tool can accommodate workpieces of different diameters.

The cutting bit 14 is mounted in a bit carrier 21 which is p-ivotally connected to the body 10 by a pivot pin 22. The axis of the pivot pin 22 lies in a transverse plane indicated by the chain line 23, which plane is perpendicular to the axis 16. The cutting tip of the tool 14 lies in another transverse plane 24 which is parallel to the plane 23. The plane 23 lies to the rear of the plane 24 by a distance a. For clarity, in FIGURE 1 the distance a is much exaggerated. The expressions front and rear as used herein designate respectively the parts of the box tool that are nearest to, and farthest from, the tip of the workpiece 13 at the beginning of its advance into the tool.

A stop formation 25 on the body 10 limits the extent of clockwise rotation of the bit carrier 21 and hence defines the closest limiting position of the bit 14 to the axis 16-.

In operation, as the workpiece is advanced in the direction of the arrow 17, a torque is exerted upon the bit carrier 21 tending to turn it in the clockwise direction in FIGURE 1 and so hold it against the stop formation 25. On the other hand, when the workpiece is withdrawn in the opposite direction to the arrow 17 the drag on the bit 14 will tend to turn the carrier slightly in the anticlockwise direction so that the tip of the tool 14 will move for a short distance in the direction of the arrow 26 along an are 27, the centre of which is the pivot pin 22. Since the plane 23 of the pivot pin 22 is to the rear of the plane 24 of the tip of the bit, any movement of the tip of the bit 14 along the are 27 in the direction of the arrow 26 will increase the radial distance from the axis 16 to the tip of the bit, i.e. the tool will open slightly and permit free withdrawal of the workpiece =13.

If the bit 14 engaged the workpiece 13 at the side, i.e. in a horizontal plane containing the axis 16 as shown in dotted lines, the same relieving effect would occur on withdrawing the workpiece, since the upward movement of the bit resulting from anti-clockwise movement of the bit carrier '21 would swing the tip of the bit upwardly in a vertical plane tangential .to the side of the workpiece. Indeed, a relieving eflect Will occur upon withdrawal of the workpiece wherever the bit engages it, provided the point of contact is not below a horizontal plane containing the axis 16.

In FIGURES 2 to 5 parts which correspond to those shown diagrammatically in FIGURE 1 have been given the same reference numerals. In this case there are two burnishing rolls and 15 which have separate carriers and N both of which are adjustable radially in slots and 30 (FIGURE 3) and which can be locked in the desired position of adjustment by clamping

bolts

31 and 31 The bit carrier 21 is provided with a groove 32 which accommodates the bit 14 (FIGURE 4), which is clamped between an arcuate pad 33 in one wall of the groove 32 and screws 34 which pass through the opposite wall of the groove 32. The bit carrier 21 has a lug portion 35 which is accommodated in a slot of corresponding width in the body 10 and which is bored to receive the pivot pin 22.

In this practical embodiment the range of movement of the bit carrier 21 is very small; a thousandth of an inch or so of movement at the tip of the bit is sufficient. The limits of this range of movement are determined by two stops. One of these stops is constituted by a screw 35 (FIGURE 5) having a lock nut 37. This screw corresponds to the stop formation 25 shown in FIGURE 1 in that it determines the innermost limiting position of the bit 14, i.e. it limits the anti-clockwise motion of the bit carrier 21 in FIGURE 5, about the pivot pin 22. The other stop limits the outward movement of the bit M by limiting the clockwise movement of the bit carrier 21 in FIGURE 5. This stop comprises a screw 38 the head 39 of which is accommodated in a recess 40 in the body 10. When the carrier 21 is against the first mentioned stop screw 36, there is a small clearance of about a thousandth of an inch or so between the underside of the head 39 and the base of the recess 40. As the bit carrier 21 moves clockwise in FIGURE 5 upon Withdrawal of the workpiece to the left, the stop screw 38 moves with it until the underside of the head 3? comes up against the base of the recess 40. The extent of this movement can be adjusted by screwing the screw 38 in or out. The stop screw 38 is locked in its adjusted position by means of a grub screw 41.

Surrounding the stop screw 38 is a coil spring 42 which lightly biasses the bit carrier 21 in the clockwise direction in FIGURE 5. This biasses the tool towards the open position. The loading of the spring is readily overcome when a workpiece is introduced into the tool, from the left in FIGURE 5.

What I claim as my invention and desire to secure by Letters Patent is:

1, A burnishing box tool adapted to be applied axially over one end of a relatively rotating workpiece, said box tool comprising a body, at least one burnishing member, means mounting said burnishing member on said body, a bit having a cutting tip, a bit carrier, means fixedly mounting said bit in said bit carrier, pivot means mounting said bit carrier on said body for pivotal movement about an axis lying in a transverse plane perpendicular to the rotational axis of said work piece and to the rear of a parallel transverse plane containing said cutting tip of said bit and stop means carried by said body and disposed to support said bit carrier with said cutting tip of said bit in its rearmost position.

2. A burnishing box tool according to claim 1 which has at least one adjustable stop which determines at least one limit pivotal position of said bit carrier.

3. A burnishing box tool according to claim 1 in which said bit is adjustable relatively to said bit carrier.

4. A burnishing box tool according :to claim 1 and including spring means biassing said bit carrier towards a limit pivotal position in which said cutting tip of said bit is at its farthest from said rotational axis of said workpiece.

References Cited in the file of this patent UNITED STATES PATENTS 427,902 Porteous May 13, 1890 1,056,097 Hartness Mar. 18, 1913 1,085,800 Crandall Feb. 3, 1914

Claims

1. A BURNISHING BOX TOOL ADAPTED TO BE APPLIED AXIALLY OVER ONE END OF A RELATIVELY ROTATING WORKPIECE, SAID BOX TOOL COMPRISING A BODY, AT LEAST ONE BURNISHING MEMBER, MEANS MOUNTING SAID BURNISHING MEMBER ON SAID BODY, A BIT HAVING A CUTTING TIP, A BIT CARRIER, MEANS FIXEDLY MOUNTING SAID BIT IN SAID BIT CARRIER, PIVOT MEANS MOUNTING SAID BIT CARRIER ON SAID BODY FOR PIVOTAL MOVEMENT ABOUT AN AXIS LYING IN A TRANSVERSE PLANE PERPENDICULAR TO THE ROTATIONAL AXIS OF SAID WORK PIECE AND TO THE REAR OF A PARALLEL TRANSVERSE PLANE CONTAINING SAID CUTTING TIP OF SAID BIT AND STOP MEANS CARRIED BY SAID BODY AND DISPOSED TO SUPPORT SAID BIT CARRIER WITH SAID CUTTING TIP OF SAID BIT IN ITS REARMOST POSITION.