Process and system for austempering metal workpieces
AssigneeALD Vacuum Technologies GmbH
InventorsVolker HEUER, Gunther SCHMITT, Robin VIEL
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Abstract
In a process and an apparatus for austempering, metal workpieces and optional tempering bodies are quenched in a quenching volume V of a quenching apparatus, in which the quenching volume V is flowed through by a cooling fluid, and the workpieces are tempered by thermal radiation of the tempering bodies, by thermal radiation of one or more heating elements arranged in the quenching apparatus, or by a thermal fluid in such a way that an average temperature T(t) of the workpieces follows a progression over time according to the relationship T ( t ) = T 0 + T 1 [ 1 + tanh ( - t τ ) ] where t is the time in seconds, 150° C.≤T0≤250° C., 600° C.≤T1≤820° C., 12 s≤τ≤24 s, 0 s≤t≤Γ and 180 s≤Γ≤240 s.
Claims15
A method of austempering metallic workpieces, comprising the steps of:
- arranging the workpieces on a batch carrier;
- optionally arranging one or more tempering bodies on the batch carrier;
- optionally arranging a metallic reference body on the batch carrier;
- thermally or thermochemically treating the workpieces arranged on the batch carrier and optionally the tempering bodies and/or the reference body, where the workpieces are heated to a temperature of 750 to 1100° C.;
- arranging the batch carrier together with the workpieces and optionally the tempering bodies and/or the reference body in a quench volume V of a quench apparatus;
- quenching the workpieces and optionally the tempering bodies and/or the reference body, where
- (a) a cooling fluid is allowed to flow through the quench volume V, and
- (b) the workpieces are tempered
- with thermal radiation from the tempering bodies,
- with radiation from one or more heating elements disposed in the quench apparatus, or
- with a heating fluid;
- wherein an average temperature T(t) of the workpieces has a progression against time according to the relationship
- T
-
- (
- t
- )
- =
- T
- 0
- +
- T
- 1
- [
- 1
- +
- tanh
-
- (
- -
- t
- τ
- )
- ]
- where t denotes time in seconds, 150° C.≤T0≤250° C., 600° C.≤T1≤820° C., 12 s≤τ≤24 s, 0 s≤t≤Γ and 180 s≤Γ≤240 s.
A system for austempering metallic workpieces, comprising:
- one or more batch carriers for the storage of workpieces;
- optionally one or more tempering bodies composed of a metallic material, graphite or carbon fiber-reinforced graphite (CFC);
- optionally a reference body composed of a metallic material;
- a furnace for the thermal or thermochemical treatment of workpieces disposed on one or more batch carriers and optionally tempering bodies and/or the reference body, where the furnace is designed and set up to heat the workpieces up to a temperature of 750 to 1100° C.;
- and
- a quench apparatus comprising
- a quench chamber having a quench volume V for accommodation of one or more batch carriers comprising workpieces and optionally tempering bodies and/or the reference body;
- a vessel for cooling fluid and a fluid drive controllable by electronic closed-loop control for the flow of cooling fluid through the quench volume V;
- one or more temperature sensors for the measurement of a temperature T(t) of the workpieces or a temperature of the reference body;
- optionally one or more heating elements controllable by electronic closed-loop control;
- optionally an electrically heatable vessel for a heat fluid and a valve controllable by electronic closed-loop control and/or a flow drive controllable by electronic closed-loop control for the charging of the workpieces with heat fluid;
- and
- an electronic controller having a control program, where the fluid drive for the cooling fluid, the temperature sensors, the optional heating elements, the optional valve and the optional flow drive for the heat fluid are connected to the electronic controller;
- wherein the quench apparatus is designed and set up to cool down the workpieces such that an average temperature T(t) of the workpieces has a progression against time according to the relationship
- T
-
- (
- t
- )
- =
- T
- 0
- +
- T
- 1
- [
- 1
- +
- tanh
-
- (
- -
- t
- τ
- )
- ]
- where t denotes time in seconds, 150° C.≤T0≤250° C., 600° C.≤T1≤820° C., 12 s≤τ≤24 s, 0 s≤t≤Γ and 180 s≤Γ≤240 s.
Dependencies are inferred from the claim text.