DK144597B

DK144597B - PNEUMATIC TENSION BODY

Info

Publication number: DK144597B
Application number: DK332973AA
Authority: DK
Inventors: M Mayer
Original assignee: M Mayer
Priority date: 1972-06-16
Filing date: 1973-06-15
Publication date: 1982-04-13
Also published as: NO136957C; FR2189654B1; NO136957B; IT989098B; FR2189654A1; US3811667A; DK144597C; GB1390576A; ES415985A1; SE404317B; JPS5417467B2; CH577877A5; NL7308455A; BE800979A; JPS4935967A

Description

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Den foreliggende opfindelse angår et pneumatisk tilspænciings-organ for arbejdsemner og af den i indledningen til krav 1 angivne art.The present invention relates to a pneumatic clamping member for workpieces and of the kind specified in the preamble of claim 1.

Sådanne sikkerhedstilspændingscylindre benyttes, jævnfør be-5 skrivelsen til det tyske fremlæggelsesskrift 1.552.653, især inden for træindustrien til at fastklemme træet under bearbejdningen, men også til sammenpresning af træforbindelser såsom dør- og vinduesrammer. Deres væsentlige formål er at forhindre ulykker, især håndknusninger, der kan opstå på grund af de al-10 mindeligt benyttede pneumatiske cylindres store stødkraft, når arbejderen imod forskrifterne holder hænderne mellem spænde-organet og emnet.Such safety clamping cylinders are used, cf. the specification of German Patent Specification 1,552,653, especially in the timber industry for clamping the wood during machining, but also for compressing wood joints such as door and window frames. Their essential purpose is to prevent accidents, especially hand crushes, which may occur due to the high impact force of the commonly used pneumatic cylinders when the worker holds the hands between the clamping member and the workpiece.

Ved de kendte tilspændingscylindre forekom der hyppigt håndeller fingerbeskadigelser, når hånden uagtsomt førtes ind mel-15 lem emnet og tilspændingscylinderpladen. Det i det nævnte fremlæggelsesskrift beskrevne sikkerhedstilspændingsorgan, skal forhindre dette. Ved dette kendte organ virker en med den bevægelige trykplade forbundet indstillingsskrue på en føle-stift og bevirker en omkobling, kort før indspændingsstillin-20 gen nås. Dette organ forudsætter, at indstillingsskruen skal efterindstilles for hver gang at tilpasse organet til det pågældende emne, fordi trykpladen ellers allerede standses, medens der endnu er en afstand mellem klembakkerne og emnet.In the known tightening cylinders, frequent hand or finger damage occurred frequently when the hand was negligently inserted between the workpiece and the tightening cylinder plate. The safety clamping device described in said disclosure document must prevent this. By this known means, an adjusting screw connected to the movable pressure plate acts on a feeler pin and causes a switching shortly before the clamping position is reached. This means that the adjusting screw must be reset for each time to adjust the means for the workpiece, because otherwise the pressure plate is already stopped while there is still a distance between the clamping trays and the workpiece.

Denne efterindstilling, der er nødvendig for at få et regel-25 ret forløb af arbejdsfunktionerne, er omstændelig og tidsrøvende. Desuden tillades ved dette kendte indspændingsorgan en fremføring med stor trykkraft, der under ugunstige betingelser også kan føre til legemsbeskadigelse.This resetting, which is necessary to get a regular run of work functions, is cumbersome and time consuming. In addition, by this known clamping means, a conveyor with high compressive force is allowed, which under adverse conditions can also lead to bodily damage.

Fra beskrivelsen til USA patent nr. 2.805.447 kendes endvide-30 re en hydraulisk presse med to forskellige stempeldiametre, ved hvilken det lille stempel bevirker den store fremførings-vej, og hvor hovedtrykket først dannes, når det udskudte stempel omtrent har nået det stof, der skal presses. Også her drejer det sig dog om et organ, ved hvilken omskiftningen fra det 35 lille til det store pressetryk først skal indstilles.Further, from U.S. Pat. No. 2,805,447, a hydraulic press having two different piston diameters is known in which the small piston causes the large feed path and where the main pressure is formed only when the deferred piston has about reached that fabric. that needs to be squeezed. Here again, however, this is a means by which the switch from the small to the large pressure must first be adjusted.

2 1445972 144597

Fra USA patentskrift 2.693.752 kendes endvidere en presse til repetitiv drift, ved hvilken arbejdsfølgen for de forskellige pressetryk styres på en given måde- USA patentskrift 1.932.556 viser endvidere en presse med et hovedstempel og et hjælpe-5 stempel, der dog ikke kan opfylde de stillede sikkerhedskrav.US Patent 2,693,752 also discloses a press for repetitive operation in which the working order of the various presses is controlled in a given manner. US Patent No. 1,932,556 also shows a press with a main piston and an auxiliary piston which, however, cannot meet the required security requirements.

Det er den foreliggende opfindelses formål at anvise et forbedret sikkerhedstilspændingsorgan, der muliggør en automatisk tilpasning til alle driftsforhold, og hvor den højeste trykkraft overhovedet ikke kan komme til at virke, når der befinder 10 sig en legemsdel mellem trykplade og emne.SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved safety clamping means which allows for an automatic adjustment for all operating conditions, and where the highest compressive force cannot operate at all when there is a body part between pressure plate and blank.

Ifølge den foreliggende opfindelse tilgodeses dette formål ved, at et pneumatisk tilspændingsorgan af den indledningsvis nævnte art er ejendommeligt ved det i den kendetegnende del af krav 1 anførte. Følestiftens funktion er snævert knyttet 15 til trykpladen, og denne følestift er afgørende for funktionen i forbindelse med trykpladen. Følestiften har kun en ringe diameter og sænkes, når den rammer blødt materiale, f.eks. når den rammer en hånd, flere millimeter i dette, indtil den finder den nødvendige modstand, der kræves til at omskifte ventilen.According to the present invention, this object is met in that a pneumatic clamping means of the kind mentioned above is characterized by the features of the characterizing part of claim 1. The function of the sensing pin is closely associated with the pressure plate and this sensing pin is essential for the function in connection with the pressure plate. The felt pin has only a small diameter and is lowered when it hits soft material, e.g. when it hits a hand, several millimeters into this until it finds the necessary resistance required to switch the valve.

20 Dette forhindres imidlertid af trykpladen, idet følestiften kun rager ganske lidt frem fra denne, således at det krævede modtryk ikke kan opstå ved følestiften. Det er takket være denne omstændighed, at spændeorganet ifølge den foreliggende opfindelse er ensartet funktionsdygtigt hen over hele fremfø-25 ringsvejen og således i hver position reagerer på blødt henholdsvis hårdt materiale, uden at der til forskellige emnestørrelser kræves en muligvis fejlagtig efterindstilling. Organet ifølge den foreliggende opfindelse, der undgår en sådan efterindstilling, opfylder sikkerhedsfunktionen langt bedre 30 end hidtil kendte organer, der kræver en nøjagtig indstilling og ved unøjagtig indstilling ikke kan sikre, at sikkerhedsfunktionen løses.20 However, this is prevented by the pressure plate, since the sensor pin protrudes only slightly from it, so that the required back pressure cannot arise at the sensor pin. It is thanks to this fact that the clamping member according to the present invention is uniformly functional throughout the entire conveying path and thus in each position responds to soft or hard material without requiring a different erroneous resetting for different workpiece sizes. The means of the present invention, which avoids such a post-adjustment, satisfies the safety function far better than prior art means which require an accurate adjustment and, in inaccurate adjustment, cannot ensure that the safety function is solved.

Tilspændingsorganet ifølge den foreliggende opfindelse kan på 35 i og for sig kendt måde være forsynet med to koaksiale spændingscy- 3 144597 lindre med forskellig diameter, hvoraf den første med mindre diameter bevirker fremløbet med en lille skubbekraft, hvorimod den anden ho^edtilspændingscylinder med større diameter leverer tilspændingskraften ved afslutningen af fremløbet.The clamping means of the present invention may in 35 known per se be provided with two coaxial tension cylinders of different diameters, the first of which having a smaller diameter causes the flow with a small pushing force, whereas the second head clamping cylinder of larger diameter supplies the tightening force at the end of the flow.

5 Tilspændingsorganet kan da på særlig enkel måde være udformet som angivet i den kendetegnende del af krav 2.The clamping means can then be designed in a particularly simple manner as defined in the characterizing part of claim 2.

Det i den kendetegnende del af krav 3 anførte sikrer, at der ikke dannes vakuum i hovedtilspændingscylindrens trykrum og muliggør ved hjælp af den regulerbare drøvleventil en regule-2Q ring af den tilstrømmende luft og dermed af fremføringshastigheden.The characterizing part of claim 3 ensures that no vacuum is formed in the pressure chamber of the main feed cylinder and, by means of the adjustable throttle valve, allows a regulating 2Q of the flowing air and thus of the feed rate.

En særlig pladsbesparende konstruktion opnås ved den i den kendetegnende del af krav 4 anførte, hvilket medfører bedre oversigtsforhold og dermed større sikkerhed.A particular space-saving construction is obtained by the method of claim 4, which results in better overview conditions and thus greater security.

15 Det i den kendetegnende del af krav 5-9 anførte, anviser forskellige enkle økonomiske konstruktive detaljer til yderligere at forbedre tilspændingsorganets sikkerhedsmæssige funktion.15, as stated in the characterizing part of claims 5-9, various simple financial structural details for further improving the safety function of the clamping means.

Ifølge en videre udførelsesform angivet i den kendetegnende del af krav 10 er det forudset at tilvejebringe to eller 20 flere påløbsfølere, der skal betjenes samtidig og i fællesskab for at bringe spændeorganet til fuld virkning.According to a further embodiment set forth in the characterizing part of claim 10, it is contemplated to provide two or 20 more inlet sensors to be operated simultaneously and jointly to bring the clamping member to full effect.

Nedenfor beskrives eksempelvise udførelsesformer for tilspændingsorganet ifølge opfindelsen på grundlag af tegningen. På denne viser 25 fig. 1 et snit af en første udførelsesform for en pneumatisk spændingscylinder og fig. 2 et snit af en anden udførelsesform.Below, exemplary embodiments of the clamping member of the invention are described on the basis of the drawing. On this, FIG. 1 is a sectional view of a first embodiment of a pneumatic tension cylinder and FIG. 2 is a sectional view of another embodiment.

Tilspændingsorganet ifølge fig. 1 har en forreste kappedel 10, der tjener til at fastlægge hele tilspændingsorganet på en hol 4 144597 destang 12. Fastholdelsen af den fast anbragte del af kappen kan også ske på anden måde. Denne forreste kappedel styrer en dobbeltvægget cylinder, der består af en ydervæg 14 og en indervæg 16, hvilken cylinder udgør den første cylinder, 5 fremskubningscylinderen, og som samtidig udgør stempel stangen af det deraf bårne hovedtilspændingsstempel 18.The clamping means of FIG. 1 has a front sheath portion 10 which serves to fix the entire clamping member to a hollow shaft 12. The retaining of the fixed part of the sheath may also be effected by other means. This front casing portion controls a double-walled cylinder consisting of an outer wall 14 and an inner wall 16, which cylinder constitutes the first cylinder, 5 the displacement cylinder, and at the same time constitutes the piston rod of the main tightening piston 18 thereof.

Dette hovedtilspændingsstempel 18 løber i hovedtilspændings-cylinderen 20, der er indsat i den forreste kappedel 10. Ho-vedtilspændingscylinderen 20 er afsluttet med et cylinderlåg 10 22, der er fast forbundet med et Plunger-stempel 24 af den første fremløbscylinder 14, 16. Hovedtilspændingsstemplet 18 er ved hjælp af en tilbageløbsfjeder 26 støttet mod kappens forreste del 10. Fremløbscylinderens forreste cylinderlåg dannes af et ventillegeme 28, som har en central åbning, der sty-15 rer en ventilløfter 30 med tætningsplade 32. Ventilløfteren 30 har aksiale kanaler 34, der via radiale boringer 36 i ventillegemet 28 står i forbindelse med en ringkanal 38 mellem de to cylindre 14 og 16. Denne ringkanal 38 står via boringer 40 i forbindelse med trykkammeret 42 i hovedtilspændingscylin-20 deren. Dette rum 42 står via en kontraventil 44 og en reguler bar drøvleventil 46 i forbindelse med den omgivende luft.This main tightening piston 18 runs in the main tightening cylinder 20 inserted in the front casing part 10. The high tightening cylinder 20 is terminated by a cylinder lid 10 22 which is firmly connected to a Plunger piston 24 of the first supply cylinder 14, 16. The main tightening piston 18 is supported by a return spring 26 against the front part of the casing 10. The front cylinder cover of the flow cylinder is formed by a valve body 28 which has a central opening which controls a valve lifter 30 with sealing plate 32. The valve lifter 30 has axial channels 34 which via radial bores 36 in the valve body 28 communicates with a ring channel 38 between the two cylinders 14 and 16. This ring channel 38 communicates via bores 40 in connection with the pressure chamber 42 in the main tightening cylinder 20. This compartment 42 is provided via a non-return valve 44 and a regulated bar throttle valve 46 in connection with the ambient air.

På den forreste del af ventillegemet 28 er der sat en trykplade 48 således, at den kan pendle. I en udboring 50 i denne trykplade 48 løber en følestift 52, der styres ved hjælp af 25 styrestempler 54 i en indvendig boring i ventillegemet. Føle- stiften 52 er ved hjælp af en trykskruefjeder 56 spændt i udadgående retning. Ventilen 30, 32 er ved hjælp af en trykskrue-fjeder 58 forspændt på sit leje.On the front part of the valve body 28, a pressure plate 48 is mounted so that it can commute. In a bore 50 of this pressure plate 48, a sensing pin 52, which is guided by 25 guide pistons 54, runs in an internal bore of the valve body. Sensor pin 52 is tensioned outwardly by means of a compression spring 56. Valve 30, 32 is biased on its bearing by means of a compression spring 58.

Organet arbejder således: 30 Trykmediet tilføres fremskubningscylinderen via en aksial bo ring 60 i Plunger-stemplet 24. Herved opbygges et tryk i cy-linderrummet 62, hvilket skubber cylinderen 14, 16 og tilspæn-dingsstemplet 18 fremefter. For at der ikke skal opstå noget vakuum i det under tryk stående rum 42 i tilspændingscylinde-35 ren, er kontraventilen 44 og doseringsventilen 46 tilvejebragt.The means work as follows: 30 The pressure medium is supplied to the push cylinder via an axial bore 60 in the plunger piston 24. A pressure is thus built up in the cylinder space 62, which pushes the cylinder 14, 16 and the tightening piston 18 forward. In order not to create any vacuum in the pressurized compartment 42 of the tightening cylinder 35, the check valve 44 and the metering valve 46 are provided.

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Gennem doseringsventilen 46 kan den indstrømmende luft reguleres, og på denne måde kan man indstille fremløbshastigheden for stemplet 18. Ved hjælp af det opbyggede tryk presses tæ-ningspladen 32 af ventilløfteren 30 tilsvarende kraftigt mod 5 sit leje. Hvis nu følestiften 52, der rager ca. 1 mm ud fra trykpladen 48, løber an mod et fast legeme, som f.eks. træ, metal eller tilsvarende materiale, løftes tætningspladen 32 fri, og trykket kan forplante sig på en stødagtig måde via boringerne 36 i ventillegemet og ringkanalen 38, såvel som gennem bo-10 ringerne 40 til det under tryk stående rum 42 i hovedtilspæn-dingscylinderen. Dermed får hovedtilspændingsstemplet 18 sin fulde skubbekraft. Lukkes der for lufttilførslen, og sker der samtidig en udluftning, så trykker fjederen 26 stemplet tilbage igen. Udluftningen sker herved i modsat retning, hvorved 15 den letløbende ventilløfter 30 ved hjælp af den tilbageløbende luft løftes fri.Through the metering valve 46, the inflowing air can be regulated, and in this way the flow rate of the piston 18 can be adjusted. By means of the built-up pressure, the sealing plate 32 of the valve lifter 30 is similarly forcefully pressed against its bed. If now the foil pin 52, which projects approx. 1 mm from the pressure plate 48, abuts against a solid body, such as e.g. wood, metal or similar material, the sealing plate 32 is lifted free and the pressure can propagate in a shock-like manner through the bores 36 in the valve body and the annular channel 38, as well as through the bores 40 to the pressurized space 42 in the main tightening cylinder. Thus, the main feed piston 18 gets its full thrust. If the air supply is closed and a venting occurs at the same time, the spring 26 pushes the piston back again. The venting is thereby done in the opposite direction, whereby the easy-running valve lifter 30 is lifted free by means of the recirculating air.

Den mellem fremløbscylinderen og hovedcylinderen anbragte ventil arbejder som følger: 2The valve located between the flow cylinder and the main cylinder operates as follows: 2

Ved et tænkt drivtryk på 8 kp/cm og med en diameter for Plun-20 gerstemplet 24 på 18 mm opstår der en skubbekraft på 20,35 kg. Regner man med, at fremdrivningskraften på grund af friktionsmodstanden af stemplet 18 og modtrykket af fjederen 26 forringes med ca. 4 kg, så er der i virkeligheden endnu en skubbekraft på ca. 16 kg til rådighed. Ventilløfteren 30's tætnings- o 25 plade 32 har en diameter på 15 mm og presses med 8 kp/cm ind på det tilhørende ventilleje. Der kræves således 14,24 kg modtryk til at løfte ventilpladen. Følestiften har ved trykpladen en diameter på 8 mm, således at der kræves en forholdsvis hård genstand af træ, metal eller et tilsvarende materiale for at 30 løfte ventilløfteren 30. Således som forudsat ovenfor, fordeler tilpresningstrykket på 16 kg sig ved et blødt underlag på trykpladen, der har en diameter på mindst 50 mm. Det er dermed udelukket, at der opstår et så stærkt modtryk for enden af styre- 6 144597 stemplet 54, at ventilløfteren 30 løftes. Det er nødvendigt, at ventilindsatsen 30 og 54 er delt i to dele, fordi ventilløfteren 30 til opnåelse af sikker lukning af ventilen og også til brug for udluftningen må løbe meget let. Derfor er tæt-5 ningen anbragt på styrestemplets ydre omkreds, hvilket styrestempel ved hjælp af en trykfjeder 56 trykkes udefter mod en anslagsring 64. Mellem styrestemplet 54 og stempelløfteren 30 er der et mellemrum på ca. 3/10 mm. De ovennævnte angivelser med hensyn til mål og tryk er ikke bindende, men tjener kun 10 som et eksempel. Alt efter de stillede krav kan cylinderen bygges i andre dimensioner.At an estimated driving pressure of 8 kp / cm and with a diameter of the Plunger piston 24 of 18 mm, a pushing force of 20.35 kg is produced. It is assumed that the propulsion force due to the frictional resistance of the piston 18 and the back pressure of the spring 26 is reduced by approx. 4 kg, then there is in fact another pushing force of approx. 16 kg available. The sealing plate 25 of the valve lifter 30 has a diameter of 15 mm and is pressed into the associated valve bearing at 8 kp / cm. Thus, 14.24 kg of back pressure is required to lift the valve plate. The sensing pin has a diameter of 8 mm at the pressure plate, so that a relatively hard object of wood, metal or similar material is required to lift the valve lifter 30. As provided above, the compressive pressure of 16 kg is distributed on a soft base on the pressure plate. having a diameter of at least 50 mm. It is thus excluded that such a strong back pressure occurs at the end of the control piston 54 that the valve lifter 30 is lifted. It is necessary that the valve inserts 30 and 54 are divided into two parts, because the valve lifter 30 for safe closing of the valve and also for the use of the vent must run very easily. Therefore, the seal is disposed on the outer circumference of the guide piston, which guide piston is pressed outwards by means of a compression spring 56 against a stop ring 64. Between the guide piston 54 and the piston lifter 30 there is a space of approx. 3/10 mm. The above mentioned dimensions and pressures are not binding but only serve as an example. Depending on the requirements, the cylinder can be built in other dimensions.

Tilspændingsorganet ifølge fig. 2 udviser en forreste kappedel 10, der tjener til fastlægning på en holdestang 12. I kappedelen 10 styres i langsgående retning en cylinder 14, der dan-15 ner en hul stempelstang til brug for hovedtilspændingsstemplet 18, der løber i en med kappen 10 forbundet hovedtilspæn-dingscylinder 20, der er lukket med et cylinderlåg 22. Hoved-tilspændingsstemplet 18 støttes ved hjælp af en som trykskrue-fjeder udformet tilbageløbsfjeder 26 mod kappen 10's forreste 20 del. Bagsiden af hovedtilspændingsstemplet 18 er til stadighed via en aksial indstrømningsåbning 25 påvirket af et tryk. Inden for en aksial boring i hovedtilspændingsstemplet 18 forskydes i aksial retning et ventillegeme 32, der har en bageste tætningsskive 17 og en forreste tætningsskive 19. Den bageste 25 tætningsskive 17 samvirker med et ventilringleje 25 i hovedtilspændingsstemplet 18, og den forreste tætning 19 samvirker med den bageste ende af den første cylinder 14. Ventillegemet 32 har en styrebøsning 27, der kan forskydes i aksial retning på en bolt 29, der er skruet ind i en aksial udboring 31 af en 30 skubbestang 24, som styres, således at den kan forskydes i aksial retning i cylinderen 14, idet der forefindes en ringspalte 33 omkring skubbestangen 24. Ved den øvre ende er denne ringspalte 33 aflukket ved hjaalp af en tætning 45 mellem cylinderen 14 og skubbestangen eller -stemplet 24. Derhos er 35 ringspalten 33 via radiale udluftningsudboringer 35 forbundet med den omgivende luft. Ventillegemet 32 er støttet ved hjælp 144597 7 af en på bolten 29 påskruet møtrik 37, og der er indføjet en trykskruefjeder 39 mellem ventillegemet 32 og den bageste ringflade af stemplet 24, hvilken fjeder 39 forspænder ventillegemet 32 i bagudgående retning. Skubbestangen 24 bærer en føle-5 stift 52, der kan forskydes i aksial retning i en udboring 50 i en trykplade 48, som er sat på den forreste del af cylinderen 14 på en sådan måde, at den kan foretage en begrænset pendulbevægelse. En trykskruefjeder 56 støtter mod en ringflade af cylinderen 14, henholdsvis en på stemplet påsat ring 55 og tryk-10 ker følestiften 52 ind i den forreste endestilling, der er be tinget ved anslag af tætningsringen 19 mod den bageste ringflade af cylinderen 14. Herved rager følestiften en lille smule frem foran det forreste plan af trykpladen 48.The clamping means of FIG. 2 shows a front sheath portion 10 which serves to be fixed to a retaining rod 12. In the sheath portion 10 a longitudinal direction 14 is controlled by a cylinder 14 which forms a hollow piston rod for use with the main tightening piston 18 which runs in a main tightening associated with the sheath 10 sealing cylinder 20 closed with a cylinder cover 22. The main tightening piston 18 is supported by a return spring 26 designed as a compression spring 26 against the front 20 portion of the casing 10. The back side of the main feed piston 18 is continuously pressurized via an axial inflow 25. Within an axial bore of the main tightening piston 18, a valve body 32 having a rear sealing disc 17 and a front sealing disc 19. is displaced axially. rear end of the first cylinder 14. The valve body 32 has a guide sleeve 27 which can be displaced axially on a bolt 29 screwed into an axial bore 31 by a push rod 24 which is guided so that it can be displaced in axial direction in the cylinder 14, there being a ring slot 33 around the push rod 24. At the upper end, this ring slot 33 is closed by means of a seal 45 between the cylinder 14 and the push rod or piston 24. There, the ring gap 33 is via radial vent bores 35 associated with the ambient air. The valve body 32 is supported by a nut 37 screwed onto the bolt 29 and a compression screw spring 39 is inserted between the valve body 32 and the rear annular surface of the piston 24, which spring 39 bias the valve body 32 in the rearward direction. The push rod 24 carries a sensor pin 52 which can be displaced axially in a bore 50 in a pressure plate 48 which is mounted on the front portion of the cylinder 14 in such a way that it can make a limited pendulum movement. A compression spring 56 supports against an annular surface of the cylinder 14, respectively, a ring 55 mounted on the plunger and presses the sensing pin 52 into the forward end position, which is conditioned by the impact of the sealing ring 19 against the rear annular surface of the cylinder 14. the feeler pin slightly forward of the front plane of the pressure plate 48.

Tilspændingsorganets funktion er som følger: 15 Trykluften strømmer gennem boringen 23 ved det øvre cylinder låg 22 ind i det bageste cylinderkammer. I den i fig. 2 viste hvilestilling er ventilskiven 17 løftet fra lejet 25, og ventilskiven 19 slutter tæt. I overensstemmelse hermed kan trykmediet via de radiale boringer 15 inden for hovedtilspænaings-20 stemplet 18 komme fra stemplets bagside til dettes forside og udfylde det forreste cylinderkammer 13, således at der opbygges det samme tryk foran og bagved stemplet. Derved opstår der i cylinderen 20, svarende til tværsnittet af stempelstangen 14, en skubbekraft, der er afmålt således, at den overvinder tryk-25 fjederen 26's modstand og skubber trykpladen 48 frem med lille kraft. Når følestiften 52 slår an imod et hårdt materiale, forskubbes ventillegemet 32 i aksial retning bagud, således at tætningsringen 19 løftes, og tætningsringen 17 kommer ind på sit leje 25. Derved spærres luftforbindelsesvejen mellem 30 det forreste og det bageste hovedcylinderkammer, og det via udboringen 23 tilførte tryk virker med fuld kraft på hovedtilspændings s templet 18, således at dette på slagagtig måde kan bevæges fremefter med stor kraft, da det forreste cylinderkammer via ventilåbningen mellem ringen 19 og ringfladen af cylin-35 deren 14 pludselig kan udlufte den ringformede spalte 33 og de radiale boringer 35. Ved udluftningen af det forreste cy-The operation of the tightening means is as follows: The compressed air flows through the bore 23 at the upper cylinder lid 22 into the rear cylinder chamber. In the embodiment shown in FIG. 2, the valve disc 17 is lifted from the bearing 25 and the valve disc 19 ends tightly. Accordingly, via the radial bores 15 within the main tensioning 20 piston, the pressure medium can come from the back of the piston to its front and fill the front cylinder chamber 13 so that the same pressure is built up front and behind the piston. Thereby, in the cylinder 20, corresponding to the cross-section of the piston rod 14, a pushing force is measured so as to overcome the resistance of the compression spring 26 and push the pressure plate 48 forward with little force. When the feeler pin 52 strikes a hard material, the valve body 32 is displaced axially in the rearward direction so that the sealing ring 19 is lifted and the sealing ring 17 enters its bearing 25. This prevents the air connection path between 30 the front and rear main cylinder chambers and that through the bore. 23 applied pressure acts at full force on the main tightening temp 18 so that it can be moved forward with great force in a stroke, as the front cylinder chamber via the valve opening between the ring 19 and the annular surface of the cylinder 14 can suddenly vent the annular gap 33 and the radial bores 35. By venting the front cylinder

Claims

144597 linder chamber achieves the full thrust piston 18. The compression spring 39 disposed between the valve body 32 and the sensing pin 52 extended over the push rod 24 results in a resilient abandonment of the valve body, so that a safe closure of the bore at the piston also occurs when using the valve lifter. The compression spring 56 on the underside of the sensing pin 52 is intended to hold the valve body 52 securely on its bearing at the end of the cylinder 14 and to allow the sensing pin 52 to project slightly a little from the pressure plate 48. The diameter of the valve body 32 is chosen so that the valve body before the switch is similarly forcefully pressed against the bearing at the end of the cylinder 14, thereby ensuring that the sensor pin cannot be easily pressed. The diameter of the valve plate therefore determines the back pressure needed to activate the sensing pin. claims'

1. Pneumatic tapping member for workpieces and with a switch valve which in its first position causes the movement of a movable pressure plate with a small pushing force and in its second position causes an increase of the pushing force with a tensioning force, wherein the switching of it in a first position biased valve is guided from a first to a second position by one or more sensing pins, characterized in that the sensing pin (52) is slidably inwardly displaced against a spring force in a bore (50) in the pressure plate (48) in its displacement direction, the sensing pin in its extended position then projectes slightly from the contact surface of the pressure plate, and the spring pressure on the sensor pin and its cross-sectional area is such that a soft body such as a hand or finger, unlike a hard workpiece, cannot push the sensor pin inwardly into the pressure plate.

A pneumatic clamping device according to claim 1 having two coaxial tension cylinders of different diameters, the first smaller diameter actuating the flow with a small pushing force, while the second larger diameter clamping cylinder supplies the clamping force at the end of the flow, characterized by that the sensing pin (52) extends into the valve body (28) of the switch valve located between the first cylinder (14, 16) and the main tightening cylinder (20) and there, when impacted against a relatively hard object, can displace an open positioned in the valve body. and closure means (30, 32) from a first position to a second position 10 for establishing connection with the pressure chamber (42) of the main tightening cylinder (20).

Tightening device according to claim 2, characterized in that the pressure space (42) of the main tightening cylinder (20) is connected to the artificial air via a check valve (44), which is preferably connected in series with an adjustable throttle valve (46).

Tightening member according to claim 3, characterized in that the pressure plate (48) is supported by the piston rod (14, 16) of the main piston (18) on the hollow end of the piston which is hollow and forms the first 2g cylinder which acts as a flow cylinder. .

Tightening means according to claim 4, characterized in that the piston rod forming the piston cylinder is formed with double walls (14, 16) and between the walls encloses an annular channel (38) which, firstly, through bores (40) in the piston (18) communicates with the main cylinder pressure chamber (42) and, secondly, through radial bores (36) is connected to a chamber (34) of the switch valve.

Tightening means according to claim 2, characterized in that the opening and closing means arranged in the valve body (28) comprises a valve lifter (30) which carries a sealing plate (32) which is displaceably arranged in it as a valve body (28). ) designed cylinder covers and which can be influenced by the feeler pin (52).