GB2192822A - Securing device for installing tools on a press - Google Patents

Abstract

The invention relates to a device for positioning and securing a punch 24 and a bolster 20 on a press comprising a mounting table 1 provided with a groove 2 and a slider 13 movable with respect to the mounting table; the bolster 20 comprises a tenon 21 complementary in shape to the groove 2. Gripping pawls 8 screwed into the table 1 place a ground lateral surface 21a of the tenon under contact thrust against a ground lateral surface 2a of the groove (2) acting as a datum bearing surface. Threaded rods 16 engaging in holes (27, Fig. 1b in the punch 24 place a ground top surface 25a of the tenon 25 under contact thrust against the ground base 14a of a groove 14 in the slider acting as a datum bearing surface and situated in a plane at right angles to the datum bearing surface 2a of the mounting table. To mount the tools in the press, the bolster with the punch engaged therein has its tenon 21 engaged in the groove 2 and a stud 22 in one of two bores 5 before the gripping pawls 8 are moved inwardly to engage a groove 23 in the tenon 21. The slider 13 is then lowered to locate the tenon 25 and a stud 26 in the groove 14 and a bore 15 respectively and the rods 16 are screwed into the holes (27, Fig. 1b). <IMAGE>

Description

SPECIFICATION Securing device for installing tools on a press The invention relates to a device allowing of rapid installation of tools comprising two parts on machines such as presses, for the purpose of assuring a precise alignment of the two parts of the tool with respect to each other.

Tools comprising two parts are utilised in machines such as presses: a lower part fastened on a mounting table with which the machine is provided, and an upper part secured on a slide movable with respect to the said mounting table. The major trouble encountered upon placing these tools in position derives from the very high precision required in their installation on the table and the slide. As a matter of fact, the two parts of the tool should be aligned very precisely with respect to each other, to prevent premature wear of the said tool andtheproduction of workpieces displaying production defects.

As a result, the installation of the tools is a protracted and chancy operation requiring many adjustments causing stoppage of the machine. Furthermore, on the score of profitability, one and the same machine is utilised to produce parts of different series, so that the tool changes are comparatively frequent operations. It will be grasped that, under these circumstances, the installation and dismantling operations on the tools will be an appreciable factor in increasing the unit price of the parts produced.

Several devices have been devised to attempt to secure a rapid and precise installation of the tools.

The first devices devised related to the installation of so-called single tools, comprising a lower part and an upper part which were separate and not located with respect to each other. The installation of a tool of this kind consisted in securing the top part of the tool on the slider, and then in manually positioning the lower part with respect to the upper part before securing the same on the mounting table or platform. The positioning of the lower part with respect to the upper part requires numerous adjustments and does not allow a very high degree of precision to be obtained.

Improvements were devised (French Patents Nos: 1 276 006 and 2 037 362) with the object of allowing of rapid installation of one part of the tool on the press. These improved devices did not however resolve the problem raised by the need to position the two parts of the tool precisely with respect to each other.

Furthermore, the French Patent No: 2 423 328 discloses a device in which the surface of the lower part of the tool facing towards the mounting table is provided with locating bars fitting into seats provided in the said table, whereas the surface of its upper part facing towards the base of the slider, is provided with a cylindrical member fitting into a seat provided in the said base of the slider. The locating bars and the cylindrical member are provided with apertures wherein may be inserted heads of locking elements provided on the slider and the mounting table, respectively.

The locking of the tool on the press is secured by displacement of the locking elements along an axis at right angles to the mounting table of the press, this displacement causing the tools to be placed under thrust on the table and the slider against bearing surfaces parallel to this table.

To allow of displacing the tool by sliding on the mounting table, the seats of the said table are machined with a small play with respect to the locating or guiding bars. The positioning of the tool on the mounting table is consequently established with a definite lack of precision, and the selection of two surfaces parallel to the table as datum bearing surfaces does not allow of correcting the positioning defects; furthermore, the tractive forces exerted on the lower part and on the upper part of the tool upon locking these on the machine, may be axially misaligned with respect to each other, engendering tangential stresses in the assembling plane between the bottom tool and top tool and causing premature attrition of these tools.

So-called "column" devices were devised to eliminate the shortcomings of these devices.

These devices comprise a bottom sole which carries the lower part of the tool, and an upper sole which carries its upper part. The upper sole or plate is movably installed with respect to the bottom plate and is guided by columns or posts secured on this latter; at the time of utilisation, this assembly is installed on the press by securing the bottom plate on the mounting table, and the top plate on the slider. The two parts of the tool positioned with respect to each other by means of the plates (once and for all, as a rule) thus provide satisfactory displacements with respect to each other during the working stages. Each tool provided with its intermediate plates with posts nevertheless forms an assembly which is heavy, difficult to handle and unwieldy.

The present invention has the object of eliminating the disadvantages of the known devices for positioning and securing tools comprising two parts, on a press. The invention has the aim of providing a device allowing of positioning and securing the tools direct on the press without interpositioning intermediate plates between the machine and the tools.

An essential object of the invention is to allow of rapid installing and dismantling operations on the tool, whilst assuring a strict alignment of the two parts of the tool with respect to each other.

(To simplify the description, the upper part of the tool secured to the slider will be denoted by the term "punch", the lower part of the tool secured on the mounting table being denoted by the term ''bolster". This terminology is justified by the fact that the lower part is formed by a female element as a general rule.) The device aimed at by the invention, intended for positioning and securing a tool on a press, is of the kind comprising a mounting table provided with a groove, a slider displaceable with respect to the said mounting table in a direction at right angles to the same, and means of securing the punch and the bolster on the slider and the mounting table, the bolster being provided with a tenon having a form matched for the aforesaid groove; according to the present invention, the said device is characterised in that - the groove of the mounting table has a surface ground at right angles to the plane of the said table or parallel to the same, intended to act as a datum bearing surface, the tenon of the bolster has a ground datum surface matched to the datum bearing surface of the groove of the mounting table, - with respect to the mounting table, the slider has a ground surface at right angles to the datum bearing surface of the said mounting table, intended to act as a datum bearing surface, - with respect to the slider, the punch has a ground datum surface matched to the datum, bearing surface of the slider, - the securing means comprise means of gripping the tenon of the bolster in the groove of the mounting table, organised to place under contact thrust and hold the datum surface of the said tenon against the datum bearing surface of the mounting table, - the securing means comprise means of gripping the punch on the slider, organised to place under contact thrust and hold the datum surface of the said punch against the datum bearing surface of the slider.

The selection, as datum surfaces, of pairs of surfaces situated in orthogonal planes-allows as will be grasped more clearly later-of a precise positioning of the tool on the mounting table and of a strict alignment of the bolster and of the punch with respect to each other without introducing interference stresses parallel to the plane of the table. Holding the datum surfaces of the bolster and of the punch under contact thrust against the datum bearing surfaces is performed by the gripping means allocated to the mounting table and to the slider, which operate along orthogonal axes, the one being parallel to the table and the other perpendicular to the same.

The means of gripping the part of the tool (bolster or punch) whereof the datum surface is orthogonal with respect to the plane of the mounting table are preferably organised to place under contact thrust and hold the said datum surface under thrust against the corresponding datum bearing surface, by means of a thrust exercised in a plane parallel to the plane of the mounting table, whereas the means of gripping the part of the tool (punch or bolster) whereof the datum surface is parallel to the plane of the mounting table, are organised to place under contact thrust and hold the said datum surface under thrust against the corresponding datum bearing surface by means of a tractive force exercised along an axis orthogonal with respect to the plane of the mounting table.

In accordance with a preferred form of embodiment which is more particularly appropriate for avertical press: - the datum bearing surface of the mounting table is situated in a plane orthogonal with respect to the plane of the mounting table and is formed by one of the ground lateral surfaces of the groove of the said mounting table, - the datum surface of the bolster is formed by one of the ground lateral surfaces of the tenon of the said bolster, - the datum bearing surface of the slider is situated in a plane parallel to the plane of the mounting table and is formed by a ground surface situated at the base of the said slider, - the datum surface of the punch is formed by the ground upper surface of the said punch.

The invention will now be described by way of example with reference to the accompanying partly diagrammatic drawings, in which: Figures 1a and 1 b are views in perspective with portions removed, respectively of a press and of a punch-bolster assembly, both being in accordance with the invention; Figure 2a is a cross-section of the press alone, along a broken line AA'; Figure 2b is a cross-section of the punchbolster assembly; Figure 3a is a cross-section along the broken line AA'; illustrating a punch-bolster assembly in process of being installed on the press; Figure 3b is a cross-section along a plane BB', illustrating a punch-bolster assembly installed on the press; Figure 4 is a longitudinal cross-section along an axial plane illustrating a punch-bolster assembly installed on the press; Figures 5 and 6 are sideviews with partial detail cross-sections, illustrating the installation of different bolster-punch assemblies on the press, and Figure 7 is a cross-section illustrating a press comprising two posts.

The device illustrated by way of example in Figures 1a, 1b, 2a, 2b allows of rapid installation of tools such as illustrated in Figures 1 b, 2b on machines such as presses illustrated in Figures 1a,2a; this device has as its function to assure precise positioning of the punchbolster assembly on the press and an alignment of high precision between the punch and bolster.

Figures 1a and 2a illustrate a press provided with a securing device for installing a bolster and a punch.

This press comprises a mounting table 1 whereon is fastened a frame 3 comprising an upward extension 3a and an angled section 3b situated above and facing the mounting table, securing and entraining means 4 for a slider 13 allowing of displacing the same along an axis at right angles to the mounting table 1.

The mounting table 1 of the press is provided with a groove 2 of rectangular crosssection formed longitudinally in the said table and whereof one extremity opens in the front surface of the same.

The groove 2 has a ground or machined lateral surface 2a situated in a plane at right angles to the plane of the mounting table and intended to act as a datum bearing surface.

At least two bores 5 within which are placed barrels placed at precisely determined different distances x and x' respectively from the groove 2, are formed in the mounting table at the same side of the groove.

The mounting table equally comprises recesses 6 of the rectangular cross-section extending in a direction at right angles to the groove 2 and opening into the said groove in the surface opposite to the ground surface 2a.

These recesses 6 equally open beneath the mounting table, the groove thus formed being closeable by means of a plate 7 fastened below the mounting table.

Gripping pawls 8 of complementary shape to that of the recesses 6 are arranged to be engaged and displaced within the said recesses. The translatory displacement in a direction at right angles to the groove 2 of these pawls 8 is assured by means of a differential pitch screw system 9.

This screw 9 comprises two portions 9a and 9b provided with screw-threads of different pitch but of identical direction; the portion which has the greater screw pitch 9b opens on to a surface 1 b of the mounting table parallel to the groove 2 via a tapped bore 10 of a diameter matching the screw-thread of the said screw; furtherrnore, this portion is provided at its extremity with a square or cruciform nut 11. The portion which has the smaller screw pitch 9a is screwed into a tapped bore 8a of matching diameter situated in the gripping pawl 8.

During their translatory movement in the recesses 6, the gripping pawls may be displaced between two positions: - one position in which they enter the groove 2, the front surface 12 of the said pawls having a plane sloping at an angle a with respect to the horizontal, - and a position in which they abut at the rear against a pin 29 situated in the recess 6.

The slider 13 which is displaceable with respect to the mounting table 1 along a direction at right angles to the said table is provided with a groove 14 of rectangular form and having a different width compared to that of the groove 2 of the mounting table 1 but positioned with strict precision above the said groove 2.

The groove 14 of the slider has a ground or machined bottom 14a situated in a plane parallel to the plane of the mounting table and consequently at right angles to the plane of the ground lateral surface 2a of the groove 2 of the said mounting table; this ground bottom 14a is intended to act as a datum bearing surface.

The slider is equally provided with a bore 15 within which a tube or barrel is situated and positioned at a particular distance x" from the groove 14, different from the distances x and x' applicable to the mounting table.

The slider furthermore comprises two stay rods 16, each being formed by a cylindrical rod of which one of the extremities 17 is screw-threaded over a particular length, the portion adjacent to the screw-threaded extremity being smooth and machined to a smaller diameter than the screw-thread diameter. The opposed extremity of each rod is smooth and provided with a square or cruciform nut or head 18.

These stay rods are arranged to be positioned in vertical seats 19 formed in the slider 13 and transpiercing the same to open in the bottom section into the groove 14 of the said slider.

The seats 19 are formed in the bottom section of the slider by a smooth bore of a depth equivalent to the height of the screw-threaded portion of the stay rods 16. Above this smooth bore is situated a tapped bore 19a having the diameter of the screw-thread of the stay rod.

Once the stay rods 16 are positioned in their seats 19, these may either be held in a high position in which their screw-threaded extremity 17 is in engagement with the tapped portion 19a of the seat 19, or be positioned in such manner as to enter into the groove 14 of the slider.

Figures 1 b and 2b illustrate a bolster-punch assembly appropriate for positioning on the press provided with the securing device.

This assembly comprises a bolster 20 provided with a tenon 21 of complementary shape to that of the groove 2 of the mounting table 1. This tenon 21 has a ground lateral surface intended to act as a datum surface and to cooperate with the surface 2a of the groove 2 of the mounting table.

Furthermore, the surface of the tenon 21 which is opposed to the ground surface 21a and required to be situated facing the gripping pawls 8 or 9 when the same is positioned in the groove 2, is provided with a groove 23 having the shape of a semi-swallowtail, apt to come into contact with the sloping surface 12 of the gripping pawls 8.

The bolster equally comprises a cylindrical stud 22 set at a distance y from the tenon 21, established to allow of positioning the said stud 22 in one of the bores 5 of the mounting table 1, when the bolster is placed on the mounting table.

This assembly equally comprises a punch 24 provided with a tenon 25 of complementary shape to that of the groove 14 provided on the base of the slider 13. This tenon 25 has a ground upper surface 25a intended to act as a datum surface and to cooperate with the ground bottom 14a of the groove 2 of the slider.

The punch equally comprises a cylindrical stud 26 set at a distance y' from the tenon 25, established to allow of positioning the said stud 26 in the bore 15 provided in the slider 13, when the punch is placed on the lower surface of the slider.

Furthermore, the top surface 25a of the tenon 25 comprises two tapped bores 27 of complementary diameter to that of the screwthread of the stay rods 16.

The punch-bolster assemblies, such as those specified in the foregoing, are placed in position on the press provided with the device described in the foregoing, in the following manner.

Before offering up the tool to the press, a check is made to ensure that the same is in the high position, that the gripping pawls 8 are not placed projectingly in the groove 2 of the mounting table 1, andthat the stay rods 16 are retracted into the high position.

The punch 24 being inserted into the bolster 20, the tenon 21 of the bolster is inserted into the groove 2 of the mounting table up to a stop position in which the positioning stud 22 of the bolster is inserted into one of the bores 5 of the mounting table.

The longitudinal positioning of the tool being assured in this manner, the next operation consists in displacing the gripping pawls 8 in their seats 6 until the sloping surface 12 of the said pawls comes into contact in the groove 23 of the tenon 21 of the bolster.

The translatory displacement of the gripping pawls 8 is assured in a precise and progressive manner by means of the differential pitch screw system; the gripping force obtained assures the locking of the bolster on the press.

The next operation consists in lowering the slider 13 as far as a position in which the tenon 25 of the punch 24 is initially positioned in the groove 14 of the said slider: the positioning stud 26 of the punch is then engaged in the bore 15 situated on the base of the slider.

Holding the punch 24 under thrust on the slider 13 is then assured by screwing the stay rods 16 into the bores 27 formed in the surface 25a of the tenon 25 of the slider.

The immobilisation of the bolster on the mounting table is thus secured by keeping the two datum surfaces of the tenon and of the groove under thrust against each other by means of the gripping pawls 8. The bolsterpunch assembly thus being positioned precisely on the mounting table, the immobilisation of the punch 24 on the slider 13 is secured by keeping their two datum surfaces formed, respectively, by the top surface 25a of the tenon 25 of the punch and the bottom 14a of the groove of the slider under thrust against each other by means of the tightening stay rods 16.

The tractive force which allows of locking the punch on to the slider is exercised along an axis at right angles to the plane of the punch and bolster assembly, so that the alignment of the two elements with respect to each other remains strictly precise (no interference displacement of any kind is induced by application of this force).

Figures 4, 5 and 6 illustrate different cases for installation of punch-bolster assemblies.

In all cases, the installation of the punches is identical and performed according to the method described in the foregoing.

Figure 4a however illustrates a bolster positioned lengthwise by insertion of the positioning stud 22 into the bore 5 which is situated in the rear part of the mounting table 1; the means of clamping the bolster 20 on the mounting table are formed by the conjointly acting gripping pawls 8.

Figure 5 illustrates a bolster open at its rear side. The longitudinal positioning is assured by means of the positioning stud 22 situated in the front part. The means of clamping the bolster on the mounting table are formed by a single gripping pawl 8.

Figure 6 illustrates the installation of a bolster which allows of performing a punching operation in overhung position with respect to its supporting base. The longitudinal positioning is assured by means of the positioning stud 22 which is situated in the rear part of the mounting table. The means of clamping the bolster on the mounting table areformed by a single gripping pawl 8.

Figure 7 illustrates an elaboration of the device described in the foregoing. The press in question comprises a twin station as a matter of fact, allowing of simultaneous installation of two punch-bolster assemblies. The displacement of the slider with respect to the mounting table is assured by means of a hydraulic or pneumatic ram 28.

Claims (12)

1. Device for positioning and securing at least one punch and at least one bolster on a press comprising a mounting table provided with a groove, a slider movable with respect to the mounting table in a direction at right angles to the said table, means of securing the punch and the bolster on the slider and the mounting table, respectively, the bolster comprising a tenon having a shape complementary to the groove of the mounting table, in which the groove of the mounting table has a ground or machined surface at right angles or parallel to the plane of the mounting table for the purpose of acting as a datum bearing surface, the tenon of the bolster has a ground datum surface matching the datum bearing surface of the groove of the mounting table, the slider is provided opposite to the mounting table with a ground surface at right angles to the datum bearing surface of the said mounting table for the purpose of acting as a datum bearing surface the punch is provided opposite to the slider with a ground datum surface matching the datum bearing surface of the slider, the securing means comprise means for clamping the tenon of the bolster in the groove of the mounting table adapted to place under contact thrust and hold the datum surface of the said tenon on the datum bearing surface of the mounting table, the securing means comprise means of clamping the punch on the slider, adapted to place under contact thrust and hold the datum surface of the said punch against the datum bearing surface of the slider.

2. Device according to claim 1, in which the means of clamping the part of the tool, bolster or punch, of which the datum surface is at right angles to the plane of the mounting table, are organised to place under contact thrust and hold the said datum surface under thrust against the datum bearing surface of the mounting table or of the slider respectively, by means of a thrust exercised in a plane parallel to the mounting table, the means of clamping the part of the tool, punch or bolster of which the datum surface is parallel to the plane of the mounting table are organised to place under contact thrust and hold the said datum surface under thrust against the datum bearing surface of the mounting table or of the slider respectively, by means of a tractive force exercised along an axis at right angles to the plane of the mounting table.

3. Device according to one of the claim 1 or 2, in which the slider is provided opposite to the mounting table with a groove intended for initial positioning of the punch on the said slider, the punch has a tenon of a shape matching the groove of the slider and intended to be positioned in the said groove.

4. Device according to claim 3, in which the datum bearing surface of the mounting table is situated in a plane at right angles to the plane of the mounting table and is formed by one of the ground lateral surfaces of the groove of the said mounting table, the datum surface of the bolster is formed by one of the ground lateral surfaces of the tenon of the said bolster the datum bearing surface of the slider is situated in a plane parallel to the plane of the mounting table and is formed by the ground bottom of the groove of the said slider, the datum surface of the punch is formed by the ground upper surface of the tenon of the said punch.

5. Device according to claims 2 and 4, in which the means of clamping the bolster on the mounting table comprise: at least one gripping pawl having one extremity matched in shape with the surface of the tenon opposite to the datum surface of the said tenon, means of guiding each gripping pawl formed by a seat wrought in the mounting table and matched in shape to the gripping pawl, the said seat extending in a direction at right angles to the groove of the mounting table and opening into the said groove, means of entraining each gripping pawl adapted to generate the displacement of the said gripping pawl in its seat along a direction at right angles to the groove of the mounting table.

6. Device according to claim 5, in which the means of entraining each gripping pawl are organised to allow of the displacement of the pawl in its seat between two extreme positions, namely a position in which the extremity of the gripping pawl enters into the groove of the mounting table, and a position in which the gripping pawl is drawn back from the groove of the mounting table and impinges against a pin situated in the seat.

7. Device according to one of the claims 5 or 6, in which the means of entraining each gripping pawl comprise a screw comprising two portions provided with screw-threads of different pitch and identical direction; a tapped bore provided at the extremity of the gripping pawl opposed to its extremity entering into the groove the said bore being arranged to cooperate with the portion of the screw having the smaller screw pitch; a tapped bore provided in a base side of the seat situated in a plane at right angles to the mounting table, the said bore opening in a lateral surface of the mounting table andbeing arranged to cooperate with the portion of the screw having the greater screw pitch, and a cruciform nut organised to be positioned on the extremity of the screw having the greater screw pitch.

8. Device according to one of the claims 5 or 6, in which the tenon of the bolster is provided in its surface opposed to the datum surface with a groove having the shape of a semi-swallowtail, and the extremity of each gripping pawl entering into the groove of the mounting table comprises a surface sloping at a salient angle a) complementary to the angle defining the groove of the tenon of the bolster.

9. Device according to claims 2 and 4, in which the means of clamping the punch on to the slider comprise at least one clamping tie or stay rod formed by a rod whereof one of the extremities has a screw-thread, the opposite extremity being provided with a cruciform nut or head; means of guiding each clamping stay rod formed by a cylindrical seat or housing formed in the slider and of a diameter matching that of the clamping stay rod, the said seat extending along an axis at right angles to the plane of the mounting table and opening into the groove of the slider on the one hand, and into the top surface of the said slider on the other hand, and means of securing each clamping stay rod on the punch, formed by a tapped bore of a diameter matching the screw-threaded extremity of the stay rod and situated in the top surface of the tenon of the punch, facing the seat of the slider.

10. Device according to claim 9, in which each seat of the slider is provided at a distance from the bottom of the groove with an internal screw-thread of a diameter matched to the external screw-thread of the clamping stay rod, and the rod forming each clamping stay rod has a smooth part of smaller diameter than the diameter of its screw-thread for the purpose of allowing of the displacement of each clamping stay rod in its seat as far as a position in which the screw-threaded extremity is engaged in the tapped bore of the seat, being a position in which the clamping stay rod is retracted from the bottom of the groove of the slider.

11. Device according to claim 3, in which the mounting table and the slider are provided with impingement means whereby it is possible to assure the longitudinal positioning of the punch-bolster assembly, the impingement means having at least two bores formed in the mounting table and whereof the position with respect to the groove of the said table is different; at at least one bore formed in the slider opposite to the mounting table, and positioning studs situated on the bolster and on the slider and matched in a diameter to the bores of the mounting table and of the slider for the purpose of engaging in the said bores upon positioning the bolster-punch assembly on the mounting table and on the slider.

12. A device as claimed in claim 1 and substantially as described with reference to the accompanying partly diagrammatic drawings.