Gyratory shear press

This invention relates to a gyratory shear press of which the compression means are disposed in the lower part of the chassis and of which the gyration means are provided in the upper part of the chassis which is in the form of a casing. The mould is introduced in the casing via an opening provided in the upper wall of the casing and adapted to be closed by a lid. The gyration means comprise two concentric sleeves separated from the casing and the mould by bearings. The inner sleeve is mounted to oscillate in the outer sleeve and is inclined by means of a vernier.

FIELD OF THE INVENTION
 The present invention relates to a gyratory shear press for compacting
 samples of compaction materials.
 It concerns more especially a press intended for studies of formulation of
 granular mixtures, for the development of new formulae and for research
 concerning the process of compacting materials used for road surfacings,
 in order to determine the behaviour of bituminous mixtures with respect to
 compaction and that of materials other than those treated with bituminous
 binding agents.
 BACKGROUND OF THE INVENTION
 In this type of press, compaction of the material is obtained by kneading,
 under low static compression, a sample of material contained in a
 cylindrical mould limited by parallel ends and maintained at constant
 temperature, to within standardized temperature tolerances.
 Kneading by shearing action is provoked by the movement of the axis of the
 mould which generates a conical surface of revolution with vertex angle
 2.alpha. while the ends remain at all times perpendicular to the axis of
 the conical surface.
 The resultant axial force F applied to the ends of the sample, the
 temperature of the mould and the angle .alpha., are maintained constant
 for the whole duration of the test. The cross-section and mass of the
 sample do not vary during the test, but the height reduces continually.
 For each sample, the height and the shearing force are measured and
 memorized as a function of the number of gyrations.
 U.S. Pat. No. 5,275,056 and WO 95/22751 disclose gyratory shear presses in
 which the mould comprises a peripheral ring extending outwardly and
 maintained between rollers disposed at different levels and driven in
 rotation about a vertical axis and which ensure tilting of the mould. In
 these two documents, the means for compressing the material of the sample
 are arranged above the mould and the latter rests on a fixed table. These
 arrangements bring about difficulties for replacing a mould containing one
 sample by a second mould containing another sample, and for making checks
 on several samples with different parameters, as it is difficult and long
 to check and change the angle a.
 U.S. Pat. No. 5,323,655 discloses a gyratory shear press in which the
 compression means are likewise arranged above the mould, the latter
 resting on a rotating table mounted out-of-center on a rotating plate.
 Here, it is necessary to ensure a relative movement between the lower end
 of the mould and the rotating table. This is effected by a ceramic disc
 interposed between the lower end and the rotating table.
 In all these documents, the means for compressing the sample contained in
 the mould are arranged in the upper part of the apparatus, which increases
 the volume and consequently the mass of the apparatus, and brings about
 difficulties in positioning the mould before the test and for removing the
 sample after compaction.
 It is an object of the present invention to propose a gyratory shear press
 which overcomes these drawbacks.
 SUMMARY OF THE INVENTION
 To that end, the invention relates to a gyratory shear press for compacting
 samples of compaction materials, comprising:
 a chassis
 a cylindrical mould of axis X adapted to receive a sample interposed
 between an upper end and a lower end, maintained parallel to each other;
 means for compressing the sample, borne by said chassis and adapted to
 apply a constant effort on one of said ends along an axis Y perpendicular
 to said ends;
 means for inclining axis X of the mould with respect to axis Y;
 gyration means adapted to impart a gyratory movement of axis X about axis
 Y;
 means for controlling the compression means and the gyration means; and
 means for measuring the heights of the sample between the ends and the
 shearing efforts of the sample as a function of the number of gyrations of
 axis X.
 The invention attains its object in that:
 a) the chassis comprises in its upper part a casing whose rigidity is
 constant over 360.degree. and which presents, in its upper wall, an
 opening adapted to be closed by a lid intended to serve as bearing for the
 upper end, and, in its lower wall, an orifice for the passage of a mobile
 element of the compression means, which is in abutment on the lower end;
 b) the gyration means comprise an outer cylindrical sleeve of axis Y
 mounted to rotate in the casing via bearings, an inner cylindrical sleeve
 of axis X mounted to rotate about a counter-mould of axis X intended to
 receive the mould, via bearings, and means for driving the outer
 cylindrical sleeve in rotation, said drive means being borne by the
 casing; the inner cylindrical sleeve being disposed inside the outer
 cylindrical sleeve and being mounted to oscillate thereon so as to be able
 to pivot about an axis Z perpendicular to axes X and Y and lying
 substantially in the plane of the upper end;
 c) the means for inclining axis X of the mould with respect to axis Y
 comprise an angle-adjusting system interposed between the outer
 cylindrical sleeve and the inner cylindrical sleeve and lying in the
 median plane perpendicular to axis Z.
 The following advantageous arrangements are furthermore adopted:
 The lower part of the chassis comprises a lower plate, an upper plate on
 which the casing is fixed, and a plurality of columns parallel to axis Y
 and connecting the lower plate to the upper plate, the lower plate
 supporting the compression means.
 The compression means comprise an endless screw driven by second drive
 means and a sheath driven in translation along axis Y by the endless
 screw, and whose head is in abutment on the lower end, said sheath being
 guided along axis Y by rollers cooperating with the columns and traversing
 an opening made in the upper plate with interposition of a bearing bush. A
 plate with a low coefficient of friction is interposed between the head of
 the sheath and the lower end. The second drive means comprise an electric
 servomotor with reduction gear and a displacement encoder.
 The angle-adjusting system is provided with a vernier and a door is
 arranged in the peripheral wall of the casing in order to access the
 vernier. The means for measuring the shearing efforts comprise a shear
 sensor placed inside the angle-adjusting system. Electrical supply of the
 shear sensor and transmission of the data picked up by the sensor are
 ensured by a rotating collector.
 The casing comprises an inductive detector for counting the number of
 revolutions of the outer cylindrical sleeve.
 The press according to the invention advantageously further comprises a
 mould-handling system, comprising a bracket disposed above the upper wall
 of the casing and a winch disposed above the lid and supported by the
 bracket.

DESCRIPTION OF PREFERRED EMBODIMENT
 Referring now to the accompanying drawings, the Figures show a gyratory
 shear press 1 which comprises a chassis 2 whose lower part 3 comprises a
 lower plate 4 and an upper plate 5 connected by three columns 6 and
 protected by a cowling 8 and whose upper part 7 is in the form of a hollow
 rigid casing having a cylindrical peripheral wall 9 of revolution about a
 vertical axis Y, an upper wall 10 comprising an opening 11 concentric to
 axis Y and a lower wall 12 fixed on the upper plate 5 and presenting a
 passage 13 of axis Y. The upper part 7 further comprises a sleeve 14 of
 axis Y which extends under the upper wall 10 opposite passage 13. The
 rigidity of casing 7 is constant over 360.degree..
 The opening 11 may be obturated by a lid 15 which serves as bearing for the
 upper face of an end 16 disposed in the top part of a cylindrical mould 17
 of axis X mounted to slide in a cylindrical counter-mould 18. In the
 bottom part of the mould 17 there is provided a lower end 19 which may
 slide in the mould 17. The space in the mould 17 defined by the upper end
 16 and the lower end 19 is filled with a sample 20 of a compaction
 material, subjected, on the one hand, to an effort or compression F
 exerted on the lower end 19 in the vertical direction Y, and, on the other
 hand, to a gyratory movement of axis X about axis Y.
 The effort of compression F is exerted by the head 21 of a sheath 22 of
 axis Y which passes through an opening 23 of axis Y made in the upper
 plate 5, with the interposition of a bush 24. A plate 25 made of material
 with a low coefficient of friction is interposed between the head 21 and
 the lower face of the lower end 19. The sheath 22 is driven in vertical
 translation in the direction of axis Y by an endless screw 26 mounted on
 the lower plate 4 and disposed inside the sheath 22, the latter presenting
 in its lower part an inner thread 27 cooperating with the outer thread of
 the endless screw. The sheath 22 is, in addition, guided during its
 vertical translation by rollers 28 which roll on the outer wall of the
 columns 6.
 The endless screw 26 is driven in rotation, by means of pulleys 29, 30 and
 a belt 31, by a constant-moment servomotor 32 driving a reduction gear 33
 on which the pulley 30 is mounted.
 The servomotor 32 is equipped with an angle encoder 34 of which the
 measurement is representative of the height of the sample 20 contained in
 the mould 17, between the lower end 19 and the upper end 16. The
 servomotor 32/reduction gear 33 assembly is disposed above the lower plate
 4, while the pulleys 29, 30 and the belt 31 are disposed beneath the lower
 plate 4, the latter comprising a plurality of stands 35, adjustable in
 height.
 The device for gyrating the mould 17 comprises an outer cylindrical sleeve
 40 of axis Y mounted to rotate inside the casing 7 by means of a first
 bearing 41 borne by the sleeve 14 and a second bearing 42 mounted on the
 periphery of the passage 13 of the lower wall 12, and an inner cylindrical
 sleeve 43 which is disposed inside the outer sleeve 41 and mounted thereon
 so as to be able to oscillate about a horizontal axis Z lying
 substantially in the plane of the lower face of the upper end 16, as shown
 in FIG. 5.
 Two bearings 44 and 45 are interposed between the inner cylindrical sleeve
 43 and the counter-mould 18, in order to allow rotation of these two parts
 with respect to each other, while preventing their relative displacement
 in the direction of axis X of the mould 17.
 A device 50 for adjusting the angle .alpha. between the axis X of the mould
 17 and the vertical axis Y, is provided in the median vertical plane
 perpendicular to axis Z. This device 50 is borne by the outer sleeve 40
 and cooperates with a screw/nut system 51 fast with the inner sleeve. It
 comprises a vernier 52 and an effort sensor of which electrical supply and
 data transmission are ensured by a rotating collector 53.
 In order to allow access to the vernier 52 and adjustment of angle .alpha.,
 the peripheral wall 9 of the casing 7 is provided with a door 54 for
 access.
 The outer peripheral sleeve 40 is driven in rotation by an electric motor
 55a driving a synchronous belt 55.
 The casing 7 is, in addition, equipped with an inductive detector 56
 serving to count the number of revolutions of the outer cylindrical sleeve
 40.
 The vernier 52 allows a setting of the angle .alpha. at 0.degree., which
 makes it possible to produce test pieces with parallel faces perpendicular
 to axis X, to effect controls of the apparatus, and a setting of the same
 angle .alpha. from 30' to 2.degree. per step of one minute in a very short
 time, and without control means.
 On the rear of the lower part 3 of the frame 2, there is provided a switch
 cabinet 57 which ensures electrical supply of the drive motors 32 and 55a
 and of the different measuring instruments.
 To the right of the frame 2 there is fixed, by screws, a panel 60 which
 comprises the on-off switches 61 of the machine and which supports a
 microocomputer 62 controlling the machine. There are connected to the
 microcomputer 62 a keyboard 63 for introducing the characteristics of the
 materials to be monitored, a screen 64 for displaying the results of each
 sample and possibly other accessories, such as mouse, data-storage device,
 etc. . . . The microcomputer 62 is connected to the angle encoder 34 which
 furnishes the measurement of the height of the sample to the inductive
 detector 56 and to the effort sensor placed inside the device for
 adjusting the angle .alpha., in order to allow storage of the data during
 gyration of the mould 17 and possibly processing thereof.
 To the left of the casing 7 there may be fixed a bracket 70 which supports
 an electric winch 71 above the lid 15 for handling the mould 17.
 The gyratory shear press described hereinabove operates as follows:
 A sample 20 of material is disposed in the mould 17 between the two ends 16
 and 19.
 The mould 17 filled with material is placed in the counter-mould 18 via the
 upper opening 11, the head 21 of the sheath 22 in that case being in lower
 position, i.e. slightly above the upper plate 5. The lid 15 is then fixed
 in the opening 11 by screwing. At the beginning of the series of tests,
 the demi-vertex angle .alpha. of the cone of gyration is displaced by
 means of the vernier 52. The constant-moment servomotor 32 is switched on,
 which brings about an increasing vertical effort on the lower end 19 which
 places the sample 20 in a state of initial compression. When the force of
 compression attains value F, the motor 55a attains its nominal test speed,
 and therefore generates rotation of axis X of the mould about axis Y, axis
 X describing a conical surface of which the vertex 0 lies in the middle of
 the lower face of the upper end 16. Such gyration provokes shear-kneading
 of the sample 20. During gyration of the mould 17, the upper end 16 and
 the lower end 19 remain parallel to each other and perpendicular to the
 vertical axis Y. For the whole duration of the test, the resultant axial
 force F applied to the ends of the sample 20 and the angle a are
 maintained constant within standard tolerances.