US2359044A - Impact tester - Google Patents

Description

IMPACT TESTER Filed April 26, 1941 4 Sheets-Sheet l ATTORNEY Sept. 26, 1944. L, MacBRIDE 2,359,044

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( V ATTORN Sept. 26, 1944. H. L. MacBRlDE 2,359,044

IMPACT TESTER Filed April 26, 1941 4 Sheets-Sheet s INVENTOR. ,W-(L/ I? 9 1 BY.

ATTORNE Y Sept. 26, 1944' H. L. Ma BRlDE 2,359,044

IMPACT TESTER Filed April 26, 1941 4 Sheets-Sheet 4 INVENTGR haw/QM ATTORNEY iOl Patented Sept. 26, 1944 vuvu vll IMPACT TESTER Herbert L. MacBride, Philadelphia, Pa., assignor to Tinius Olsen Testing Machine Company, Philadelphia, Pa., a corporation of Pennsylvania Application April 26, 1941, Serial No. 390,443

13 Claims.

This invention relates to a testing machine of the impact type, wherein the resistance of a specimen to breaking under sudden impact is measured by the travel of a pendulum hammer after the breaking of the specimen.

The impact tester is adapted to make Izod tests, Charpy tests, and Tension tests of specimens.

In testing machines of the impact type, it has heretofore been deemed necessary when Izod and Charpy tests are to be made to remove one type of knife from the pendulum hammer or bob and replace it with another type of knife, since both Izod and Charpy tests are not made with the same knife.

One object of the present invention is to devise a novel impact tester, wherein the Izod knife and the Charpy knife, as well as the socket to receive one end of a tension specimen, form a single unit, mounted in a novel manner in the pendulum hammer, and adjustable to bring into operative position the knife or socket to correspond to the selected test which is to be made.

A further object of the invention is to devise novel clutching and releasing means for the pendulum, so that when released it will start its stroke without any impulse or retarding action.

A further object of the invention is to devise novel means for clamping an Izod, Charpy or Tension specimen in position for impact.

A further object of the invention is to devise novel braking mechanism which will arrest the oscillations of the pendulum in a minimum of time.

With the above and other objects in view as will hereinafter clearly appear, my invention comprehends a novel impact tester.

It further comprehends a novel frame, a novel pendulum hammer, a novel knife unit, novel clamping mechanism for the different types of specimens, novel clutch mechanism and novel brake mechanism.

Other novel features of construction and advantage will hereinafter clearly appear in the detailed description and the appended claims.

For the purpose of illustrating the invention, I have shown in the accompanying drawings a typical embodiment of it, which, in practice, will give satisfactory and reliable results. It is, however, to be understood that the various instrumentalities of which my invention consists can be variously arranged and organized and my invention is not limited to the exact arrangement and organization of these instrumentalities as herein set forth.

Figure 1 is a front view of an impact tester embodying my invention.

Figure 2 is an elevation.

Figure 3 is a section on line 3-3 of Figure 5 showing the vise and clamping mechanism.

Figure 4 is a perspective view of a portion of the vise and clamping mechanism with an Izod type specimen.

Figure 5 is a top plan view of Figure 3.

Figure 6 is a perspective view of a portion of the vise and clamping mechanism with a Charpy type specimen.

Figure '7 is a sectional elevation of the hammer attached to the pendulum arm.

Figure 8 is a perspective view of the knife unit.

Figure 9 is an end view of the hammer.

Figure 10 is an end view of a portion of the bob opposite to that shown in Figure 9.

Figure 11 is a perspective view of a clamping bar for a tension test specimen.

Figure 12 is a front elevation of a clutch.

Figure 13 is a front elevation of the clutch with a cover plate removed.

Figure 14 is a top plan view of the clutch.

Figure 15 is a rear elevation showing the braking mechanism.

Similar numerals of reference indicate corresponding parts.

Referring to the drawings:

l designates the base of an impact tester embodying my invention. The base has a standard 2 fixed to the base and rising from it and in the form of a channel, the upper end of which is in the form of an enlarged head 3. The base I, standard 2, and head 3 are preferably metal castings to provide the required rigidity for the frame and may b cast integral or connected in any desired manner.

The base I has a vise block 4 fixed to it by fastenin devices 5 in the apertures 6. The block 4 has a slot 1 in its top face and is angularly cut away to receive a specimen jaw 8 having a slot 9, the walls of which converge towards a clamping jaw Iii having a. vertically disposed recess ll opening through its front wall to receive an Izod specimen and having angular recesses l2 to receive a Charpy specimen. The rear wall of the clamping jaw l0 has a recess l3 and the wall M of this recess l3 inclines downwardly and outwardly to conform with the cooperating wall of a clamping nut l5 which is adjusted by a clamping screw H5 in threaded engagement therewith. The clamping screw I6 is rotatably mounted in the vise block which latter is recessed to receive a worm gear I! keyed to the clamping screw and meshing with a manually rotatable worm shaft I8 journalled in a bearing |9. A thrust bearing 20 is disposed between the worm gear l1 and the vise block. A spring block 2| is fixed to the vise block by a bolt 22 and form an abutment for the clamping nut IS. The rear end of the spring block 2| is recessed to receive a spring 23 which bears against the rear end bar of a yoke 24 having a cover plate 25 secured to it and cut out at its front end to clear the clamping nut l5. The vise block 4 is chambered at 26 and has an opening 21 through which an Izod specimen 28 can be ejected from the recess H, see Figures 3 and 4 A Charpy test specimen 29 is shown in testing position in Figure 6.

The standard 2 and head 3 has a shaft 38 journalled in it, see Figure 15, and a pendulum arm 3| is fixed to the shaft 38 in any conventional manner. The lower end of the pendulum arm is flanged to receive bolts 32 to rigidly connect it with a hammer 33 forming the pendulum bob.

The pendulum hammer and knife unit The hammer 33 i of channel formation having depending, spaced sides 34 which are provided with hammer weights 35. 36 is a knife unit, see Figure 8, having angularly spaced Charpy and Izod knives 31 and 38 respectively, a threaded tension socket 39, and a counterbalancing lug 48. A square lug 4| extends from the rear wall of the unit and terminates in a round rod 42 received in an aperture 43 in the hammer. The square lug 4| has a key 44 adapted to seat in one of the keyways 45 spaced 90 apart in the hammer.

The front wall of the knife unit has an aperture 46 to receive the reduced end 41 of a striking bit rod 48 slidable longitudinally in the hammer and locked in position by a jam screw 49 bearing against the outer end of the rod 48. The rod 48 has a threaded recess 58 to receive a bolt to provide means for pulling out the rod which has a press fit in the knife or striker unit 36. The hammer has a cut out 52 to enable the operator to reach in and rotatably adjust the knife unit to position it for a selected test.

The sides of the hammer are recessed at their rear as at 53 to receive a clamping bar 54 having an opening to receive the shank of an internally threaded clamping screw 55, the head of which abuts against the clamping bar 54 to secure a tension test specimen 56 in testing position.

The pendulum arm 3| has secured to it a keeper 51 which cooperates with a novel clutch mechanism 58, see Figures 12, 13 and 14. The clutch mechanism 58 has a rear latch plate 59 centrally recessed and a front plate 68, said plates being bifurcated at their lower portions to provide clearance for the pendulum arm. The plates 59 and 60 are secured in selected position by the screws 6|, with the head 3 of the frame, which latter has vertically aligned apertures The screws are inserted in selected apertures 5| in accordance with the height at which it is desired to latch the pendulum arm. A latch 62 is pivoted at 63 to the latch plate 59, and a cooperating latch 64 is pivoted at 65 to the latch plate 59. The latches have jaws 66 at their lower ends to engage the keeper 51. Springs 61 tend to move the latches towards each other and in contact with a cam 68 on a shaft 69, journalled in the latch plates and having a handle 10, the movement of which is limited by a bracket 1|.

The braking mechanism The shaft 30, to which the pendulum arm is secured, has also fixed to it a brake drum 12, having a brake lining 13, around which a brake band '14 passes. One end of the brake band is pivotally connected to one end of a lever 15 pivoted at 16 to a bracket 11, bolted rigidly to the standard 2. The other end of the brake band is secured to the bracket 11. An adjustable stop screw 18, carried by the bracket I1, is in the path of the lever 15 to limit the downward movement of a snubber 19, which is integral with the lever 15. A cord 88 passes around a reel 8|, eccentrically secured to the brake drum 12. The location of this reel is such that when the pendulum is latched in any operating position for a test, the cord 88 leads approximately across the center of the pendulum shaft, thus not applying when it is released, any movement to either assist or retard the pendulum. The cord 88 makes a complete turn around the snubber l9 and is kept taut by a weight 82. The lever 15 has a cam 83 with reversely inclined faces 84 in the path of a roller 85 carried by the brake drum.

The measuring mechanism Any desired type of measuring mechanism may be employed. As illustrated, a linear type is shown which is actuated when an arm of the pendulum arm actuates a conventional slide. Two scales are employed, see Figure 1, a Charpy scale 86 graduated in 264 foot pounds, and an Izod scale 81 graduated in foot pounds. The Charpy scale is also used for the tension test.

A hammer rest 88 is pivoted to the standard 2, so that it can be swung into the path of the hammer when a. test specimen is being inserted or removed.

The jaw 8 is held to the vise block by fastening devices 89, and the clamp |8 is secured to the yoke 24 by fastening devices 90.

The operation will now be apparent to those skilled in this art and is as follows:

The outer end of the shaft I8 is shaped to receive a handle for turning it.

If an Izod test is to be made, the Izod test specimen is inserted from the top, see Figure 4, into the recess II and the shaft l8 turned to revolve the clamping screw I6 and thereby cause the clamping nut l5 to advance the clamp II] towards the jaw 8 to rigidly clamp the Izod test specimen in position. The jam screw 49, see Figure 7, is loosened and the knife unit 36 moved forwardly to bring the key 44 out of its keyway 45. The operator inserts his hand in the opening 52 and turns the knife unit to bring the Izod knife 38 into operative position, moves the unit rearwardly to cause the key 44 to enter the selected keyway 45, and tightens the jam screw 49. The pendulum is now raised to cause the jaws of the latch mechanism to engage the keeper on the pendulum arm.

The arm I8 is actuated to release the latches 62 and 64, and the pendulum arm and hammer swing downwardly. The leading edge of the Izod knife is in a vertical plane at the moment of impact and is in the axis of the pendulum so that impact occurs at the nadir of the swing. The specimen is fractured and the pendulum arm swings up on the reverse side until the unconsumed energy is expended. The difference in height between the initial and reverse side positions of the hammer is the measure of the energy consumed and their difference is measured by the measuring mechanism and is read on the Izod scale.

If a Charpy test is to be made, the Izod test specimen is removed and a Charpy test specimen 29 is positioned as shown in Figure 6. The knife unit is adjusted to bring a Charpy knife into operative position with its leading edge in the vertical plane at the moment of contact and in the axis of the pendulum, and the knife unit is then locked in adjusted position by the jam screw 49.

The pendulum is raised to be held by the latch mechanism, and then released. The Charpy specimen is fractured and the reading is taken on the Charpy scale.

For a tension test, the tension test specimen 56, see Figure 7, is screwed into the tension socket 39, the clamping bar 54 placed in the recesses 53 and the specimen holder 55 screwed to the specimen.

The pendulum is raised, latched and released as before and the bar strikes the jaw 8.

The reading is taken on the Charpy and Tension scale.

The operation of the brake is as follows:

The inclined center line in Figure indicates the position of the pendulum ready to drop for the Charpy test. When the pendulum is released the brake drum rapidly rotates in a counterclockwise direction, as seen in Figure 15, which is a view from the rear of the machine. The cord 80 is paid out from the reel BI, and slack is taken up by the falling of weight 82. However, the slack, owing to frictional resistance of the snubber I9, is taken up slowly enough so that the weight 82 does not apply any assisting force to the falling pendulum. With the cord slack, the lever 15 rests against the screw 18 and the brake band I4 is loose, and does not brake the drum during the fall of the hammer. On the return stroke, the snubbing action of cord 80 pulls up on lever ll, tightening the band 14. Friction of this band on the drum tends to tighten it further, resulting in a powerful braking effect operating on the return stroke only.

When the hammer is lifted all the way up to the latching position for another test, the roller 85, just before the latching position is reached, passes over the cam 83', pushing it and the lever 15 down. This disengages the brake which will remain inoperative until the return swing after release.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an impact tester, a frame, a vise block on said frame, a jaw on said vise block, a clamp having its inner face recessed to receive a specimen, a manually controlled clamping member to move said clamp towards said jaw to clamp a specimen in impact position, a specimen breaking hammer mounted to oscillate on said frame, and a knife unit rotatably adjustable in said hammer and having a working tool secured in impact position by adjustment of said unit.

2. In an impact tester, a frame, a pendulum mounted to oscillate on said frame and having a keeper, latches pivotally supported and having rounded portions to engage said keeper to retain the pendulum in raised position, yielding means tending to move the latches towards each other, a cam between said latches to release them, and means to actuate said cam.

06d! bll nuulll 3. In an impact tester, a frame, a specimen breaking hammer mounted to oscillate on said frame, a vise body on said frame, a stationary jaw on the vise body, a clamp to receive a specimen, a yoke connected with said clamp, a stationary block on said vise body, a clamping unit between said stationary block and said clamp, means between said stationary block and yoke tending to move said clamp and yoke rearwardly, and. a manually controlled clamping screw for said clampingunit.

4. In an impact tester, a frame, a specimen breaking hammer mounted to oscillate on said frame, a vise body on said frame, a stationary jaw on said vise body, a clamp, a yoke connected with said clamp, a stationary block on said body, a clamping nut between said clamping nut and said clamp, said clamping nuts and clamp having cooperating inclined faces, means between said stationary block and yoke tending to move said clamp and yoke rearwardly, and a manually controlled clamping screw for said nut.

5. In an impact tester, a frame, a pendulum shaft rotatably mounted thereon, a pendulum fixed to said shaft and braking mechanism for said pendulum comprising a brake drum fixed to said shaft, a brake band, a lever to which one end of the band is connected, a member connected with the outer end of the band and having means to press against said lever, a snubber on said lever, a reel on the drum, a weighted cord passing around said reel and snubber, a cam on said lever, and means on said drum cooperating with said cam to turn said lever to release the brake band on the initial swing of the pendulum, the band being in braking engagement with the drum on the reverse swing of the pendulum.

6. In an impact tester, a knife unit having a body portion with 9. lug having a key and terminating in a rod, said body portion at the opposite side from said lug having a rod receiving aperture, and said body portion having an impact member thereon.

7. In an impact tester, a frame, a vise mechanism, a pendulum mounted to oscillate on said frame and provided with a chambered hammer having a recess and an aperture to slidably receive a striking bit rod, a knife unit having a rod to be received in said recess and an aperture to receive said striking bit rod, said unit having a working tool a striking bit rod longitudinally slidable in said hammer and extending into said aperture, and a jam screw to lock the striking bit rod in locking position.

8. Th construction specified in claim '7, with the hammer having a cut out to enable the operator to reach in and rotatably adjust the knife unit when the jam screw is in its unlocked position.

9. Braking mechanism for an impact tester having a shaft, a pendulum arm and means to latch the pendulum arm in operating position, comprising a brake drum fixed to said shaft, a roller on the brake drum, a stationary bracket, a lever pivoted to the bracket and having a snubber, a cam on the lever with reversely inclined faces in the path of said roller, a brake band passing around the drum, having one end fixed to the lever and the other end fixed to the bracket, an adjustable stop member on the bracket in the path of the lever to limit downward movement of the snubber, a reel on the brake drum, a cord passing around the reel and the snubber, and a weight at the free end of the cord, said cord when the pendulum is latched leading approximately across the center of the pendulum shaft.

10. The hereindescribed new article of manufacture for impact testers, comprising a knife unit having a body portion, with impact members and a balancing lug, said body portion having at one end a rod for rotatably supporting it and a key, and having its opposite end adapted to receive means to lock the unit in its adjusted position.

11. In an impact tester, a frame, means on said frame to retain an Izod specimen in impact position, a pendulum mounted to oscillate on said frame and having a specimen breaking hammer provided with bearing means, a knife unit rotatably adjustable in said bearing means and carrying an Izod knife, and means to lock said unit in the position to which it has been rotatably adjusted.

12. In an impact tester, a frame, means on.

said frame to retain a Charpy specimen in impact position, a pendulum mounted to oscillate on said frame, and having a specimen breaking hammer provided with bearing means, a knife unit rotatably adjustable in said bearing means and carrying a Charpy knife, and means to lock said unit in the position to which it has been rotatably adjusted.

13. In a tester, a frame, an abutment on the frame, a pendulum mounted on the frame and having a hammer provided with bearing means, a member rotatably adjustable in said bearing means and having a socket to receive a tension test specimen, means to fix said member in its adjusted position, a clamping bar mounted in the hammer and cooperating with said abutment, and means to secure a specimen in said socket with the clamping bar.

HERBERT L. MACBRIDE.

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