US2909955A - Headstock for lathes and the like - Google Patents

Description

Oct. 27, 1959 T. V. WILLIAMS HEADSTOCK FOR LATHES AND THE LIKE Filed April 19, 1957 T Memr Unite rmAnsrocK non LATHES AND THE Lnm Application April 19, 1957, Serial No. 653,835

2 Claims. (CI. 82-40) This invention relates to headstocks of the type having a conical center for engagement in a central recess in the end of the stock and driving dogs engaging the end of the stock in spaced relation to the center for turning the stock.

Objects of the invention are to provide a headstock which is simple and economical in construction, in which the dogs automatically bite into the end of the stock in response to pressure from the tailstock, in which the dogs automatically adjust to irregularity in the stock so that each dog gets a firm grip on the stock, and which is durable and reliable in use.

According to the present invention the headstock has an axial bore for the center and one or more off-center bores for the driving dog or dogs, the center and dogs being slidable endwise in the bores, together with hydraulic or other means for forcing the dogs outwardly when the center is forced inwardly. In the preferred embodiment the head has an interior passageway interconnecting the rear ends of the bores, the passageway and the aforesaid ends being filled with grease or other fluid so that the dogs are forced outwardly when the center is forced inwardly. When using a plurality of driving dogs they are preferably distributed equidistantly around the center bore.

For the purpose of illustration a typical embodiment of the invention is shown in the accompanying drawings in which:

Fig. 1 is an end View;

Fig. 2 is a side view with parts broken away;

Fig. 3 is a section on line 3-3 of Fig. 1; and

Fig. 4 is a section on line 4-4 of Fig. 2.

The particular embodiment of the invention chosen for the purpose of illustration comprises a headstock formed in two parts 1 and 2, the front part 2 fitting in a recess in the forward face of the rear part 1 and the two parts being secured together by means of screws 3. The rear part 1 may be mounted on the face of the rotating part of a lathe 4 by means of screws extending through the openings 6. The forward part 2 is provided with an axial bore 7 and three smaller bores 8 radially offset from the axial bore and uniformly distributed around the axial bore. Slidably fitted in the axial bore is a center 9, the rear end of the bore being enlarged and the center having a flange 10 seating against the shoulder between the two bores. The center 9 is urged forwardly by means of a spring 11. Slidably mounted in each of the offset bores is a plunger 12 having on its rearward end a flange 13 fitting in the enlarged rearward portion of the bore 8. A spring 14 between the flange 13 and the shoulder between the two bores urges the plunger 12 rearwardly. The forward end of each of the plungers 12 is bifurcated radially and in the bifurcation is pivotally mounted a dog 16 on a pin 17, the forward edges of the dogs being beveled circumferentially so that the leading edges bite into the end of the stock S. The inner end of each dog preferably extends into a recess 18 in the center 9. While the inner ends of the dogs should fit the recesses fairly snugly, they should be freely movable in the recesses so that the dogs are self-aligning. The rear Patent M 2,909,955 Patented Oct. 27, 1959 ends of the bores interconnect through a passageway 19 in the part 1. As shown by stippling the rear ends of the bores and the passageway 19 are filled with a fluid such as grease, so that when the center 9 is forced rearwardly the plungers 12 are forced forwardly. The passageway 19 may be filled through a fitting 21 and duct 22 with a bleeder 23 in the opposite end of the duct which is removed during the filling operation. Around the center 9 and the plungers 12 are provided sealing irlingis 24 and 26 to prevent the escape of the aforesaid In the absence of stock the center 9 is held in its forward position by spring 11 and the plungers 12 are held in their rearward positions by springs 14 so that the center 9 projects beyond the dogs 16 as shown in Fig. 2. When the stock S is placed between the headstock and tailstock in the usual way, adjustment of the tailstock toward the headstock forces the center 9 to the rear against the action of spring 11 and this movement of the center forces the plunger 12 forwardly to embed the dogs 16 in the end of the stock. Owing to the fact that each plunger moves independently of the others under the same pressure, the dogs 16 embed themselves in the end of the stock uniformly, notwithstanding irregularities in the shape of the stock. When the stock is removed the springs return the parts to the position shown in Fig. 2. As illustrated the area of the rear end of center 9 is equal to the sum of the rear ends of the plungers 12 but if desired the area of the center may be less than the sum of the areas of the plungers or vice versa, thereby to augment or decrease the force applied to the plungers by the center.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. A headstock comprising a rotary head having an axial bore and off-center bores distributed equidistantly around the center bore, a center fitted in the axial bore and plungers fitted in the ofi-center bores, the center and plungers being slidable endwise in said bores, means forcing the plungers outwardly when the center is forced inwardly, and driving dogs having stock-engaging edges, the dogs being pivotally mounted on the projecting ends of the plungers so that said edges are self-aligning.

2. A headstock comprising a rotary head having an axial bore and off-center bores distributed equidistantly around the center bore, the head having an interior passageway interconnecting the rear ends of the bores, a center fitted in the axial bore and plungers fitted in the off-center bores, the center and plungers being slidable endwise in said bores, said passageway and ends being filled with fluid so that the plungers are forced outwardly when the center is forced inwardly, and driving dogs having stock-engaging edges, the dogs being pivotally mounted on the projecting ends of the plungers so that said edges are self-aligning.

References Cited in the file of this patent UNITED STATES PATENTS 2,191,137 Trible Feb. 20, 1940 2,270,009 Rath Jan. 13, 1942 2,612,071 Kurzweil Sept. 30, 1952 FOREIGN PATENTS 100,805 Germany Mar. 17, 1898 380,160 Germany Sept. 3, 1923 409,864 Italy Mar. 5, 1945 725,439 Great Britain Mar. 2, 1955 740,850 Great Britain Nov. 23, 1955 847,672 Germany June 26, 1952

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